RESULTS DIPHTHERIA PHOSPHATE TOXOID

Bull. Org. mond. Sante 1954, 10, 951-982Bull. Wld Hlth Org.

RESULTS OBTAINEDWITH DIPHTHERIA PHOSPHATE TOXOID

A. TASMAN, Ph.D.National Institute of Public Health, Utrecht, Netherlands

J. D. LEBRET, M.D.Municipal Public-Health Service, Zeist, Netherlands

Manuscript received in June 1954

SYNOPSIS

An investigation was recently carried out in the Netherlands todetermine the value of Diphtheria Phosphate Toxoid-a highlypurified aluminium-phosphate-adsorbed toxoid prepared at theNational Institute of Public Health, Utrecht-for active immuniza-tion against diphtheria. The authors describe the procedure followedin this study, in which 4,272 persons of both sexes and of agesranging from under 1 year to 70 years were inoculated with thevaccine, and give a detailed analysis of the results obtained.

Investigation Procedure

Since 1949, a vaccine for active immunization against diphtheria hasbeen prepared at the National Institute of Public Health, Utrecht, Nether-lands, under the name of Diphtheria Phosphate Toxoid (abbreviated toDiphtheria PT). This vaccine consists of a highly purified diphtheria-toxoid adsorbed on aluminium phosphate.

Two articles on the subject of this vaccine have already been published(Noordam et al. 15 and de Graaf et al. 5). The first dealt with the applicationof this vaccine to 67 adult volunteers, members of the staff of the NationalInstitute of Public Health, Utrecht, and to 227 infants (4-5 years of age)from Amsterdam; the second was a report on the immunization of 256pupils of the Jac. P. Thijsse Montessori Lyceum at Overveen.

The practical results of these immunizations were very good, the vaccinebeing tolerated well both by adults and by children, and the Schick conver-sion-rate being about 98%-98.5%. At the same time, however, some otherfacts came to light (connexion between the inoculation reactions and theSchick positivity or negativity of the persons inoculated, correlation betweeninoculation reactions, sex and age of the immunized persons), which

- 951-310

952 A. TASMAN & J. D. LEBRET

could not be further inquired into owing to the limitations of the availablematerial.

These results led to an extension of the investigation, a large numberof children of the Zeist schools being given the same treatment as the pupilsof the Montessori Lyceum at Overveen had received. In order to supple-ment the material as much as possible, and in order to bring higher andlower age-groups within the scope of the investigation, a number of childrennot attending school and of adults were also immunized. Most immuni-zations of schoolchildren were carried out in the course of the scholasticyear 1950-1 a; the majority of the children not attending school and ofthe adults were immunized in the years 1952 and 1953. The durabilityof the immunity obtained was checked in the school years 1951-2 and 1952-3.As the children and adults at Zeist were treated in the same way as thepupils of the Montessori Lyceum at Overveen, the latter (256 persons)have also been included in the present study. The statistical compilationof the material was carried out by the Netherlands Foundation of Statistics(Nederlandse Stichting van Statistiek) at The Hague.b

The vaccine used, Diphtheria PT, consists of a highly purified diphtheria-toxoid adsorbed on aluminium phosphate, and contains 30 Lf (flocculationunits according to Ramon 17) and 10 mg ofAlPO4 per ml, thiomersal (sodium-ethyl-mercury-thiosalicylate) being added as a preservative in a dilutionof 1/10,000. The purity of the diphtheria toxoid used in the vaccine duringthe investigation was about 1,500 Lf per mg of protein nitrogen.c

The investigation covered 4,272 persons. To all of these the Schicktest was applied after some personal data (name, age, school, whetherpreviously immunized, whether previously infected with diphtheria) hadfirst been collected. The Schick reagent was injected intracutaneouslyinto the inner side of the left forearm, the " control fluid " being correspond-ingly injected into the skin of the right arm. This control fluid consistedof the Schick reagent, d heated at 800C for 20 minutes.

The result of the Schick test e was read after 2-4 days, whereupon eachperson was given an intramuscular injection of 0.5 ml of Diphtheria PT.

a The authors wish to acknowledge their great indebtedness to the Municipal Corporation of Zeist,to Mrs. J. A. M. Keers, head of the Municipal Public-Health Service, and to headmasters, principals, masters,and teachers of all the educational institutions that they were able to include in the investigation.

b Special thanks are due to Mr. J. van Tulder and Mr. A. Verhey for very valuable consultations duringthe compilation of the material.

c The diphtheria vaccine and the combined vaccines now obtainable contain a purified diphtheria-toxoidof 2,000-2,200 Lf per mg of protein nitrogen.

d The Schick reagent used in the investigation conforms to the statutory requirements embodied in theNetherlands Ministerial Decree of 10 January 1936 (Nederlandse Staatscourant, 10-11 January 1936, No. 7;translated into French in Bull. Off. int. Hyg. publ. 1936, 28, 2129).

e With regard to the result of the Schick test, the following four possibilities exist:-,-; i.e., negative with respect to both the non-heated and the heated Schick reagent, and thereforeto be regarded as Schick-negative.+, + ; i.e., equally positive with respect to the non-heated and the heated Schick reagent, and there-fore also to be regarded as Schick-negative (positive pseudo-reaction).+,- ; i.e., positive with respect to the non-heated and negative with respect to the heated Schick reagent,and therefore to be regarded as Schick-positive.+ +, + ; i.e., more strongly positive with respect to the non-heated than with respect to the heatedSchick reagent, and therefore also to be regarded as Schick-positive (positive genuine and positive pseudo-reaction).

DIPHTHERIA PHOSPHATE TOXOID

A few days later the " inoculation reaction " was judged by one of us(A.T.). Of course, this judgement was more or less subjective, being of thenature of a personal impression. The fact, however, that all the reactions(both those after the first and those after the second injection) were judgedby the same person assured the closest approach to a uniform appreciationof these reactions. This conclusion is further supported by the fact that thereactions, if any, were preponderantly of a local character and couldtherefore be appreciated objectively. Only a small proportion of the inocu-lated persons showed general reactions: temporary indisposition, riseof temperature, and confinement to bed. Naturally, these general reactionsare subjective and coloured by the individuality of the inoculated persons(or their parents, in the case of little children).

One month after the first inoculation, only those whose first Schickreaction had been positive were once more tested by means of this reagent.Two to four days after this, the result of this second Schick test havingbeen read, all these persons (including those whose Schick reaction afterone inoculation had been negative) were inoculated for the second time(0.5 ml of Diphtheria PT). After from two to four days, the reaction tothe second inoculation was judged. Four weeks after the second inoculation,those persons whose second Schick reaction had been positive were givenanother Schick test. Out of 1,199 persons whose first Schick reaction hadbeen positive, only 3 still reacted positively to this third Schick test. Thesewere subjected to a repetition of the whole process (inoculation, examinationof inoculation reaction, fourth Schick'test). They all three finally showeda negative reaction to the fourth Schick test.

At this point a small theoretical error in the planning of these experi-ments must be pointed out. The second Schick test was applied to ascertainthe Schick conversion-rate after one inoculation. This was found to average83.2%. Those, however, whose immunity after two inoculations was testedby means of the Schick reaction (the third Schick), had had one extraSchick injection (the second Schick) in addition to the two inoculations.

It is known that, under certain conditions, even a small dose of Schicktoxin may act as an antigen (see, for instance, Pappenheimer & Lawrence 16).According to these authors, however, this is mainly the case with personswho, while possessing only a small quantity of humoral immunity, havegreat potential or anamnestic immunity. With such persons the injectionof the Schick reagent may be a sufficiently strong antigen stimulant tocause a rapid change of the initially positive reaction into a negative one.

In our investigation this problem only concerns persons whose firstand second Schick reactions were both positive, i.e., who still reactedpositively to the second Schick test notwithstanding the fact that besidestwo Schick injections they had received one Diphtheria PT injection. Intheir case one can hardly assume great potential or anamnestic immunity.However, the fact remains that in their case this second Schick injection

953

A. TASMAN & J. D. LEBRET

may have helped to produce a negative reaction to the third Schick test.In other words, practical results (without the second Schick injection) willnot, perhaps, quite equal the very high Schick conversion-rate found aftertwo inoculations (99.7%).

Theoretically, it would have been more correct if, for the Schick testafter two inoculations, a group of persons had been taken who had nothad a second Schick injection after the first inoculation. However, thiswas impossible because of the limited material.

Most of the children under the age of 3 years were also immunizedagainst pertussis. Although the inoculation against diphtheria and pertussiscan now be carried out with a combined vaccine (Diphtheria-Pertussis PT),this method was not used for the persons we examined. In their case theimmunization against pertussis (by means of four injections of pertussisvaccine) always took place after the diphtheria immunization had beenentirely completed, i.e., after the last negative Schick reaction.

Factors Influencing Results of Investigation

Before passing to a more detailed discussion of the results obtained,some remarks of a general nature should be made.

Age ofpersons examined

Our examination of the Zeist schoolchildren had to be fitted in withthe immunization against diphtheria which is generally carried out as partof the School Health Service. Every year there is a voluntary immunizationof the pupils of the first, third, and fifth forms of the elementary school,of schools for advanced elementary education, and of higher-grade schools.Two denominational secondary schools (Christelijk Lyceum and ChristelijkeH.B.S.) fall beyond the cognizance of the municipal medical school-inspection. Hence, the pupils of these two schools are not normallyinoculated against diphtheria by the Municipal Public-Health Service ofZeist. That we could nevertheless extend our investigation to a great numberof the pupils of these educational institutions was due to special circum-stances and particularly to the whole-hearted co-operation of the head-masters of these schools.

Great difficulty was experienced in obtaining the co-operation of asufficient number of adults (20 years of age and over). Those who volun-teered were mainly members of the teaching staffs of the above-mentionedschools; the authors are grateful to them for their co-operation. However,their number (188 persons) was small compared with the number ofjuveniles from 4 to 19 years of age.

Nor did the filling of the lower age-groups (children under the ageof four years) prove to be less difficult. These children, who for the most

954

DIPHTHERIA PHOSPHATE TOXOID 955

part do not go to school, cannot be reached through any organization.In their case we had to depend entirely on the positive activity of theparents; and, in addition, our time was limited.

As will appear later, the immunization against diphtheria of the young

children that do not yet go to school is quite insufficient at Zeist (as it is,presumably, in many other places in the Netherlands).

TABLE

Age (years)

0

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21 - 25

26-30

31 -35

36-40

41 -50

51 -60

61 -70

I. AGE DISTRIBUTION OF PERSONS EXAMINED

Males Females

31 25

36 24

39 28

75 84

149 129

71 74

198 204

140 109

132 159

109 108

135 132

135 116

117 107

146 147

156 122

101 76

72 80

85 61

46 42

25 25

16 14

18 24

22 13

18 13

13 12

14 14

14 5

7 1

Fotal

56

60

67

159

278

145

402

249

291

217

267

251

224

293

278

177

152

146

88

50

30

42

35

31

25

28

19

8

Total 2,120 1,948 4,068

Average age 11.6 11.1 11.4


Table I gives the age distribution of the children and adults who wereexamined; 204 persons who had had diphtheria before, and who will bediscussed separately, are not included.

As will be seen from this table, the average age of the males was aboutsix months higher than that of the females-namely, 11.6 as against11.1 years. In view of the fact that the subsequent analysis will show thatresults varied greatly according to age, even this difference of half a yearis sufficient to render insignificant certain small differences found betweenthe results with males and with females.

Sex ofpersons examined

With regard to the distribution according to sex, the material of ourexperiment may be called good, the number of males and females beingabout the same.

Immunization history ofpersons examined

The third datum concerning the persons examined obtained before thecourse of the actual investigation was related to previous history ofimmunization. We tried to ascertain from everybody whom we examinedwhether he or she had been immunized against diphtheria prior to ourinvestigation. The analysis has shown that in a number of cases the state-ments must have been incorrect, the immunization referred to havingprobably been against pertussis or smallpox.

This mistake is most noticeable in the group of children from 6 to 7 yearsof age-children, that is to say, who are in the lowest form of the elementaryschool. This is understandable in view of the fact that for our knowledgeconcerning the immunization of these children we had to rely entirely onthe information (usually written) the parents were able to give; the teacher,moreover, often acted as an intermediary. In addition, the statement" immunized " does not reveal anything about the method or the vaccineused in this previous immunization.

Especially among the persons over 3 years of age there will be manywho were injected at an earlier date with so-called " fluid " toxoid. For aneffective immunization with this prophylactic, at least three injections arerequired (see Noordam et al.15). It is by no means certain that the personsin question all received this number of injections. Animal experimentshave, moreover, shown that two Diphtheria PT injections give considerablyhigher immunity than can be obtained by giving three injections of fluidtoxoid.

The figures given in table II are based on the statements made by oron behalf of the persons examined in answer to the question whether theyhad been immunized against diphtheria before; no account was taken of

956


TABLE II. IMMUNIZATION HISTORY OF PERSONS EXAMINED

Males Females TotalAge non- immunized non- immunized non- immunized

(years) total immu- total immu- total immu-nized no. %* nized no. %* nized no. %*

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21-25

26-30

31-35

36-40

41-50

51-60

61-70

31

36

39

75

149

71

198

140

132

109

135

135

117

146

156

101

72

85

46

25

16

18

22

18

13

14

14

7

31

35

37

71

133

58

126

79

58

49

46

59

52

56

57

29

23

24

16

8

5

7

13

10

9

11

10

6

0

2

4

16

13

72

61

74

60

89

76

65

90

99

72

49

61

30

17

11

11

9

8

4

3

4

0

2.8

5.1

5.3

10.7

18.3

36.4

43.6

56.1

55.0

65.9

56.3

55.6

61.6

63.5

71.3

68.1

71.8

65.2

68.0

(68.8)

(61.1)

(40.9)(44.4)

(30.8)

(21.4)

(28.6)

(-)

25

24

28

84

129

74

204

109

159

108

132

116

107

147

122

76

80

61

42

25

14

24

13

13

12

14

5

25

24

25

71

109

62

127

70

59

53

45

47

45

67

41

20

15

16

9

6

4

9

7

6

9

8

3

0

0

0

3

13

20

12

77

39

100

55

87

69

62

80

81

56

65

45

33

19

10

15

6

7

3

6

2

1

0

(0)10.7

15.5

15.5

16.2

37.7

35.8

62.9

50.9

65.9

59.5

57.9

54.4

66.4

73.7

81.4

73.8

78.6

76.0

(71.4)

(62.5)(46.2)

(53.8)

(25.0)

(42.9)(-)( -)

56

60

67

159

278

145

402

249

291

217

267

251

224

293

278

177

152

146

88

50

30

42

35

31

25

28

19

8

56

59

62

142

242

120

253

149

117

102

91

106

97

123

98

49

38

40

25

14

9

16

20

16

18

19

13

6

0

5

17

36

25

149

100

174

115

176

145

127

170

180

128

114

106

63

36

21

26

15

15

7

9

6

2

0

1.7

7.5

10.7

12.9

17.2

37.1

40.2

59.8

53.0

65.9

57.8

56.7

58.0

64.7

72.3

75.0

72.6

71.6

72.0

70.0

61.9

42.9

48.4

28.0

32.1

(31.6)

(-)

Total 2,120 1,118 1,002 47.3 1,948 982 966 49.6 4,068 2,100 1,968 48.4

Average 11. 10.3 13. 11.1 9.5 12.8 11. 9.9 12.9age 11.6 10.3 13.0 11.1 9.5 12.8 11.4 9. 1.

* In cases where the total number of persons in a group was less than 25, the percentageimmunized in given in parentheses; no percentage figures are given for any group of less than10 persons.

957


the time which had elapsed between this immunization and our treatment,or of the method used. From the data in table II it appears that on anaverage about 48% of the persons examined had been previously immunized.The figures vary greatly according to the age of the persons concerned.On the whole there is little difference between the percentages for malesand for females. We wish to draw special attention to the rise in thepercentage of previous immunizations which occurs after the sixth, theseventh, and the eighth year. As has already been mentioned, it is quitepossible that in the case of the 6- and 7-year-old children the percentageof immunizations is too high, as several children who were stated to havebeen immunized against diphtheria, or made a statement to that effectthemselves, may really have been immunized against some other disease.

Date of investigation

Before concluding this introduction, we must draw attention to theimportance of the year in which the investigation was instituted. Severalof the frequencies found in the course of the investigation are probablymore or less specific for the years 1950-1, when most of the persons wetreated were examined. If, for instance, this inquiry had been initiatedin 1953, several curves would probably have had a somewhat differentshape or a different level, though their general appearance would have beenroughly the same. One cannot, therefore, speak of universal curves. Thefollowing may serve to elucidate this line of thought.

From the results of the first Schick test and the known morbiditydistribution according to age it appears that children from 0 to 4 yearsof age are rather susceptible to diphtheria. For this group the first Schicktest gave a high proportion of positive reactions. This applies both tothose who-according to the statements-had been previously immunizedand to those who had not. If one takes the non-immunized children sepa-rately, one finds a decrease in the percentage of positive reactions to the firstSchick test in the fourth year. This decrease continues to be very markedin the sixth and seventh years, after which the curve somewhat straightensout, until about the tenth year, when the lowest percentage of positivereactions to the first Schick test is reached.

This decrease is due not only to artificial immunization, which doesnot occur to a noticeable extent until after the fourth year, but also to" natural " immunization as a result of having had a subclinical form ofdiphtheria. The large-scale effect of this natural immunization will, ofcourse, depend on the number of cases of diphtheria occurring among thepopulation in question during a certain period.

The figures for diphtheria morbidity in the years 1936-53 given intable III are derived from data published by the Centraal Bureau voor deStatistiek. 13

958


TABLE 1II. DIPHTHERIAIN THE NETHERLANDS, 1936-53

Year Number of reportedYear ~~~casesaverage 1936-9 1,289

1940 1,733

1941 5,437

1942 19,407

1943 56,790

1944 60,400

1945 50,005

1946 27,003

1947 10,390

1948 4,313

1949 3,164

1950 2,985

1951 2,765

1952 2,801

1953 2,560

From this table it may be seen that the children who frequently cameinto contact with other children in the street or in the infant school in 1946-most of them were about five years old at the time-had considerablymore chance of acquiring natural immunity than the children who werein the same circumstances in 1947 or 1948. In view of these considerations,the number of positive reactions to the first Schick test among the formergroup-those, therefore, who were 9 years of age or older in 1950may be expected to be smaller than in the case of the children who were5 or 6 years old in 1950. On this line of argument, the form of the Schickage-curve would appear to depend more or less on the year in which theinvestigation is carried out. In 1953, the percentage of positive reactionsto the first Schick test among the non-immunized 9-year-olds will haveto be higher than the percentage found in our investigation, which waslargely carried out in the years 1950 and 1951. Consequently, in 1953,the total proportion of non-immunized Schick-positive children will beon a higher level than in 1950. This will have its repercussions on the mainaverage, which will, of course, be higher too.

How far this line of reasoning also holds good for those who have beenpreviously immunized, it is impossible to determine. However, it is notunlikely that in this group, too, the number of positive reactions to the firstSchick test will to some extent be influenced by natural immunization.

959


The Schick age-curve of the persons who have been immunized before maytherefore show the same trend as the age curve of those who have not.

Results of Investigation

Result offirst Schick test

Table IV gives the results of the first Schick test, arranged accordingto the various types of reaction. As will be seen, the number of pseudo-reactions in this first Schick test forms only a small proportion of thetotal, there being no difference in this respect between the reactions of malesand of females.

TABLE IV. REACTIONS TO FIRST SCHICK TEST,SHOWING TYPE OF REACTION AND SEX OF PERSONS TESTED

Type Males Femalesof reaction *

no. of cases % of total no. of cases % of total

Negative

_ _ 1,452 68.5 1,372 70.4

+ + 24 1.1 21 1.1

total number 1,476 69.6 1,393 71.5

Positive

+ - 632 29.8 547 28.1

++ + 12 0.6 8 0.4

total number 644 30.4 555 28.5

Total number 2,120 100 1,948 100

* See footnote e, page 952, for explanation of signs.

Table V gives the results of the first Schick test, arranged accordingto the age of the persons treated and to whether they had been previouslyimmunized or not. The pseudo-reactions have been classified as positiveor negative reactions in accordance with table IV.

The category of persons not previously immunized shows a percentageof Schick-positive reactions which is about four times as high as the figurefound for those previously immunized. In view of the above-mentionedmistakes in the statements of previous immunization, and considering thenotable difference in the age distribution of the two categories, one mustnot attach an absolute value to this figure. However, the difference betweenthe two categories can be said to be significant in the sense that persons

960


TABLE V. REACTIONS TO FIRST SCHICK TEST,SHOWING AGE AND IMMUNIZATION HISTORY OF PERSONS TESTED

Non-immunized Immunized TotalAge positive positive positive

(years) total nega- t nega- total nega-ntive total tive tive

no. %* no. %* no. %*

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21-25

26-30

31-35

36-40

41-50

51-60

61-70

56

59

62

143

242

120

253

150

117

102

91

106

97

123

98

49

38

39

25

14

9

16

20

16

18

19

13

6

8

4

7

16

53

30

144

82

89

86

82

86

88

97

83

42

24

31

20

9

5

10

13

10

9

9

10

5

48

55

55

127

189

90

109

68

28

16

9

20

9

26

15

7

14

8

5

5

4

6

7

6

9

10

3

1

85.7

93.2

88.7

88.8

78.1

75.0

43.1

45.3

23.9

15.7

9.9

18.9

9.3

21.1

15.2

14.3

36.8

20.5

20.0

(35.7)

(-)

(37.5)

(35.0)

(37.5)

(50.0)

(52.6)

(23.1)

(- )

0

1

5

16

36

25

149

99

174

115

176

145

127

170

180

128

114

107

63

36

21

26

15

15

7

9

6

2

0

0

5

10

26

19

97

64

149

108

161

141

119

163

168

121

102

98

52

31

20

20

9

13

6

8

5

2

0

10

6

10

6

52

35

25

7

15

4

8

7

12

7

12

9

11

5

6

6

2

1

0

(- )

(-)

(- )

(37.5)

28.8

24.0

34.9

35.4

14.4

6.1

8.5

2.8

6.3

4.1

6.7

5.5

10.5

8.4

17.5

13.9

(4.8)

23.1

(40.0)

(13.3)

(-)

(- )

(- )

(- )

56

60

67

159

278

145

402

249

291

217

267

251

224

293

278

177

152

146

88

50

30

42

35

31

25

28

19

8

8

4

12

26

79

49

241

146

238

194

243

227

207

260

251

163

126

129

72

40

25

30

22

23

15

17

15

7

48

56

55

133

199

96

161

103

53

23

24

24

17

33

27

14

26

17

16

10

5

12

13

8

10

11

4

85.7

93.2

82.1

83.6

71.6

66.2

40.0

41.4

18.2

10.6

9.0

9.6

7.6

11.3

9.7

7.9

17.1

11.6

18.2

20.0

16.7

32.0

37.1

25.8

40.0

35.0

(21.1)

(- )

* In cases where the total number of persons in one group was less than 25, the percentageis given in parentheses; no percentage figures are given for any group of less than 10 persons.

Total 2,101 1,152 949 45.2 1,967 1,717 250 12.7 4,068 2,869 1,199 29.5

Averageaga 9.9 12.1 7.3 12.2 13.1 11.4 11.4 12.7 8.2


who have not been immunized will always yield a considerably higherproportion of Schick-positive reactions than those who have.

About 30% of all the males reacted positively to the first Schick injec-tion ; among the females, about 29%. No significant differences are foundin this respect, either between males and females generally or betweentheir separate age-groups.

FIG. 1. PERCENTAGE OF POSITIVE REACTIONS TO FIRST SCHICK TEST,SHOWING IMMUNIZATION HISTORY OF REACTORS

100 100

80 80E

u a

e 60 60 _

a i

& 40 /c cS

i.20 IL 20

0 00 2 4 6 8 10 12 14 16 18 20'

Age in yearsWHO '4312

A = no history of immunization B= history of immunization

In fig. 1 the connexion between the reactions to the first Schick testand previous immunization is shown by means of a graph. The two curves-namely, the line for those previously immunized and the line for thosenot previously immunized-represent the positive percentage of the totalnumber of results. These curves are based on the data given in table V.It is evident that the curve of positive results obtained with persons whohad not been immunized tops the other line at practically every point.

Inoculation reactions after first Diphtheria PT injectionThe first Diphtheria PT injection was given to everybody who had

been examined. On an average, 12% of all the persons treated were foundto react positively to this injection.

In table VI the reactions upon inoculation (total number of positivereactions) are arranged according to age and sex ; in table VII the reactionsare subdivided according to type and sex.

The type was judged by the criteria set forth in a previous publication(Noordam et al. 15), as follows:

962


Mild local: local reaction with redness up to a diameter of ± 3 cmLocal: local reaction with redness over 3 cm in diameterMild general: feeling indisposed in the evening, no marked rise of

temperature, well again next dayGeneral: feeling indisposed in the evening, rise of temperature,

confined to bed for from one to three days.The same criteria can, of course, be used for the combinations: mild

local/mild general ; local/mild general ; mild local/general'; local/general.As has already been pointed out, all the inoculation reactions were

judged by one of us (A.T.) personally. Most of the reactions to the firstinoculation were of a local nature; 65.0% + 5.7% = 70.7% in the caseof the males, and 69.0% + 13.6% = 82.6% in the case of the females. Thesefacts, therefore, ensure the closest possible approach to an objective judge-ment of these inoculation reactions.

On an average, 7% of the males and about 17% of the females whowere inoculated reacted positively to this first injection. Again, no signifi-cance must be attached to these percentages in themselves, as our materialwas not representative of the Dutch population.

There can be no doubt, however, about the significance of the differencebetween males and females, which cannot be attributed exclusively to thematerial of our test. In fig. 2 these inoculation percentages are expressedin the form of a graph.

FIG. 2. PERCENTAGE OF INOCULATION REACTIONSAFTER FIRST DIPHTHERIA P.T. INJECTION, SHOWING SEX OF REACTORS

o~~~~ AfeaeS ae

c Ic

&2C~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.

A c

0 00 2 4 6 8 10 12 14 16 18 20

Age in years WHO H313

A =females B =males

A study of this graph will show that both the line indicating the reactionof the females and the corresponding line for the males start at about 15%in the first year, but that the line for the boys immediately drops to 2%-3%,

963


TABLE VI. INOCULATION REACTIONS AFTER FIRST DIPHTHERIA PT INJECTION,SHOWING AGE AND SEX OF PERSONS INOCULATED

Males Females TotalAge pstv oiiepstv(years) total nega- psitve total neg total eg

tiveno. %* tive no. %* tot nega

0

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21-25

26-30

31-35

36-40

41-50

51-60

61-70

31

36

39

75

149

71

198

140

132

109

135

135

117

146

156

101

72

85

46

25

16

18

22

18

13

14

14

7

26

31

37

74

146

66

196

136

126

99

126

133

103

130

144

94

67

82

43

24

16

17

15

11

9

11

7

4

5

5

2

3

5

2

4

6

10

9

12

14

16

12

7

5

3

3

10

7

7

4

3

7

3

16.1

13.9

5.1

1.3

2.0

7.0

1.0

2.9

4.5

9.2

6.7

8.9

12.0

11.0

7.7

6.9

6.9

3.5

6.5

4.0

(0)

(5.6)

(31.8)

(38.9)

(30.8)

(21.4)

(50.0)

(- )

25

24

28

84

129

74

204

109

159

108

132

116

107

147

122

76

80

61

42

25

14

24

13

13

12

14

5

21

22

23

78

119

69

190

98

140

94

108

90

80

121

93

61

64

49

36

13

9

15

9

6

4

10

3

0

4

2

5

6

10

5

14

11

19

14

24

26

27

26

29

15

16

12

6

12

5

9

4

7

8

4

2

16.0

(9.1)17.9

7.1

7.8

6.8

6.9

10.1

11.9

13.0

18.2

22.4

25.2

17.7

23.8

19.7

20.0

19.7

14.3

48.0

(35.7)

(37.5)

(30.8)

(53.8)

(67.0)

(28.6)

(-)

(-)

56

60

67

159

278

145

402

249

291

217

267

251

224

293

278

177

152

146

88

50

30

42

35

31

25

28

19

8

47

53

60

152

265

135

386

234

266

193

234

213

183

251

237

155

131

131

79

37

25

32

24

17

13

21

10

4

9

7

7

7

13

10

16

15

25

24

33

38

41

42

41

22

21

15

9

13

5

10

11

14

12

7

9

4

16.1

11.7

10.4

4.4

4.7

6.9

4.0

6.0

8.6

11.1

12.4

15.1

18.3

14.3

14.7

12.4

13.8

10.3

10.2

26.0

16.7

23.8

31.4

45.2

48.0

25.0

(47.4)

* In cases where the total number of persons in one group was less than 25, the percentageIs given in parentheses; no percentage figures are given for any group of less than 10 persons.

Total 2,120 1,963 157 7.4 1,948 1,625 323 16.6 4,068 3,588 480 11.8

Averageage 11.6 11.1 17.2 11.1 10.5 14.3 11.4 10.8 15.2


TABLE VIl. INOCULATION REACTIONS AFTER FIRST DIPHTHERIA PT INJECTION,SHOWING TYPE OF REACTION AND SEX OF PERSONS INOCULATED

Males Females

Type of reaction no. of % of total no. of % of totalreactions ~~reactions %otta

Mild local ..... . . 102 65.0 223 69.0

Local . . . 9 5.7 44 13.6

Mild general .... . . 10 6.4 17 5.3

General . . . 10 6.4 6 1.8

Mild local/mild general 9 5.7 18 5.6

Local/mild general . 5 3.2 7 2.2

Mild local/general . 1 0.6 0 0

Local/general . . . . . . 11 7.0 8 2.5

Total number of positivereactions . . . . . . 157 100 323 100

the line for the girls going down only to about 7%. After the ninth yearthere is a rise, which is particularly marked in the reaction curve for thefemales. Broadly speaking, the lines diverge more and more every year.

We have not been able to find a satisfactory explanation for this curiousphenomenon. Scheibel et al.20 observed the same phenomenon in theirexperiments, when 825 adults between the ages of 20 and 34 were immunizedwith purified diphtheria-toxoid adsorbed on aluminium hydroxide. Theyalso found that the women inoculated by them generally reacted morestrongly to the vaccine than did the men.

Relation between result offirst Schick test and reactions afterfirst inoculationTable VIII gives the inoculation reactions (the totals of all the reactions),

arranged according to the results of the first Schick test and the ages of thepersons concerned.

Generally speaking, the Schick-negative category yielded a higherreaction percentage than those who had reacted positively to the first Schicktest: 13.3% as against 8.3%. This would seem to confirm the current viewin this matter. Scheibel et al.20 found that persons who had had diphtheriaat an earlier stage showed a greater number of positive Moloney reactions(Moloney & Fraser10' 11) than those who had never had the disease.Edsall 2 draws attention to the possibility, when immunizing adults againstdiphtheria, of eliminating those who will probably react strongly by meansof a preliminary Schick test, as only those who react positively to this testwould have to be immunized. These would react considerably less stronglyto the antigen injections than people whose reaction to the first Schicktest was negative.

965


TABLE Vil. RELATION BETWEEN REACTIONS AFTER FIRST DIPHTHERIA PTINJECTION AND REACTIONS TO FIRST SCHICK TEST

Negative reaction to 1st______ 1 Schick test

]Age reaction after(yeares) first Diphtheria PT(er) totalI injection

nega- positivetive no. 0*

0 8 6 2 (-)1

1 4 4 0 (-)

2 12 10 2 (16.7)

3 26 23 3 11.5

4 79 75 4 5.1

5 49 44 5 10.2

6 241 230 1 1 4.6

7 146 136 10 6.8

8 238 218 20_ 8.4

9 194 172 22 11.3

1 0 243 212 31 12.8

1 227 189 38 16.7

12 207 .170 37 17.9

1 3 260 222 38 14.6

14 251 214 37 14.7

15 163 141 22 13.5

16 126 111 15 11.9

17 129 115 14 10.9

18 72 64 8 11.1

19 40 30 10 25.0

20 25 20 5 20.0

21-25 30 24 I 6 I 20.0

26-30 222 15 7 (31.8)

31-35 23 1 1 12 (52.2)

36-40 15 7 8 (53.3)

41-50 1 7 1 4 3 (17.6)

51-60 15 7 8 (53.3)

61-70 7 41 3 (-)

Total 2,869 2,488 381 13.3

Averageage 12.7 12.2 15.7

Positive reaction to 1 st Total number of reactionsSchick test to 1 st Schick test

reaction aftefirst Diphtheria

total injectionnega- positiktive no.

48

56

55

133

199

96

161

103

53

23

41

49

50

129

190

91

156

98

48

21

'.4 A

24 24

17 13

33 29

27 23

14 14

26 20

17 16

16 15

10 7

5 5

1 2 8

13 9

8 6

10 61

4, 310 6

1 01,19 1,10

7

7

5

4

9

5

5

5

5

2

2

0

4

4

4

0

6

3

0

4

4

2

4

4

1

1

99

(

(I

8.2 7.7 13.6

Xr reaction afterPT first Diphtheria PT

_ total injectionve nega- positive%* tive no. %*

14.6 56 47 9 16.1

12.5 60 53 7 11.7

9.1 67 60 7 10.4

3.0 159 152 7 4.4

4.5 278 265 13 4.7

5.2 145 135 10 6.9

3.1 402 386 16 4.0

4.9 249 234 15 6.0

9.4 291 266 25 8.6

(8.7) 217 193 24 11.1

(8.3) 267 234 33 12.4

(0) 251 213 38 15.1

23.5) 224 183 41 18.3

12.1 293 251 42 14.3

14.8 278 237 41 14.7

(0) 177 155 22 12.4

23.1 152 131 21 13.8

(5.9) 146 131 15 10.3

(6.3) 88 79 9 10.2

30.0) 50 37 13 26.0

- ) 30 25 5 16.7

33.3) 42 32 10 23.8

30.8) 35 24 11 31.4

- ) 31 17 14 45.2

40.0) 25 13 12 48.0

36.4) 28 21 7 25.0

- ) 19 10 9 (47.4)

8 4l 4

8.3 4,068 3,588 480 11.8

11.4 10.9 15.2

* In cases where the total number of persons in one group was less than 25, the percentageis given in parentheses; no percentage figures are given for any group of less than 10 persons.


Our investigation, however, showed the following facts. In each age-group for which the reaction percentages could be based on a sufficientlylarge number of persons (the 3-, 4-, 5-, 6-, 7-, 8-, 13-, 14-, and 16-year-olds),the Schick-negative members seemed to react a little more strongly to theantigen injection than those who reacted positively to the first Schick test,although there was not much difference. But the average age of those whoreacted negatively to the Schick test was four or five years higher than thatof those who were Schick-positive. In view of the fact that the frequencyof the inoculation reactions increases greatly according to the age of theinoculated persons (see the last four columns of table VIII), the averagedifference in reaction percentage between those who reacted negatively tothe first Schick test and those whose reaction was positive (i.e.,13.3% - 8.3% = 5.0%) must be ascribed almost entirely to this differencein age distribution. It is not possible, therefore, on the present evidence,to establish a significant correlation between the reaction to the first Schicktest and the inoculation reaction.

Result of second Schick testA month after the first inoculation everybody who had shown a positive

reaction to the first Schick test was given another Schick injection. Thedistribution of the different types of Schick reaction of the persons concernedis given in table IX.

When comparing table IX with table IV, it will be seen that the per-centage of pseudo-reactions was slightly larger in the second Schick test.This might be due to a slight sensitization by the diphtheria antigen (preced-

TABLE IX. REACTIONS TO SECOND SCHICK TEST,SHOWING TYPE OF REACTION AND SEX OF PERSONS TESTED

Type Males Femalesof reaction* no. of cases % of total no. of cases % of total

Negative

_ _ 508 78.9 457 82.5

+ + 19 2.9 12 2.2

total number 527 81.8 469 84.7

Positive

+ - 113 17.6 84 15.2

++ + 4 0.6 1 0.2

total number 117 18.2 85 15.3

Total number 644 100 554 100

* See footnote e, page 952, for explanation of signs.

967

968

iO._ua

._a1-0._1a

cL


FIG. 3. PERCENTAGE OF POSITIVE REACTIONS TO FIRST AND SECONDSCHICK TESTS

80 iu

60 *a

p20

-7""==_MN U8 10 12 14 16 18Ag. in years

WMO 431'

A = first Schick test B = second Schick test

ing first Schick test and first inoculation). The figures are too low, however,for far-reaching conclusions to be drawn.

In table X the results of the second Schick test are arranged accordingto type and sex.

In the second Schick test, as in the first, the percentage of positivereactions of the males was a little higher than that of the females, whichcorresponded to the higher average age of the former. In this case too,therefore, it is impossible to establish any significant difference between thesexes.

Fig. 3 presents the percentage of positive reactions to the first and thesecond Schick injection in the best-filled age-groups in the form of a graph.The two lines show an analogous trend, though at widely different levels.

TABLE X. REACTIONS TO SECOND SCHICK TEST,SHOWING SEX OF PERSONS TESTED

Males Females Total

ttl nega- posi- tta nega- po tota nega- posi-l total tive tive tot e tive t tive tive

Absolute figures . 644 527 117 555 470 85 1,199 997 202

% of total . . 100 81.8 18.2 100 84.7 15.3 100 83.2 16.8

Average age . 8.3 8.1 9.3 8.0 7.7 8.8 8.2 7.9 9.1


Inoculation reactions after second Diphtheria PT injection

In all, 1,199 members of the group under investigation were inoculatedfor a second time-namely, those who had shown a positive first-Schickreaction. They were given a second antigen injection, irrespective of theresult of the second Schick test.

Table XI gives the total number of the reactions to this inoculation;the reactions are arranged according to type and sex in table XII. As in

TABLE XI. INOCULATION REACTIONS AFTER SECOND DIPHTHERIA PTINJECTION, SHOWING SEX OF PERSONS INOCULATED

Males Females Total

total nega- posl total nega- pi- total ntega - postive' tive tive tive t ive tive

Absolute figures. 644 569 75 555 455 100 1,199 1,024 175

% of total 100 88.4 11.6 100 82.0 18.0 100 85.4 14.6

Average age 8.3 7.5 14.5 8.0 6.8 13.1 8.2 7.2 13.7

this case, too, all the reactions were judged by one of us (A.T.) personally,and as most of the reactions were of the local type, it was possible to judgethem all objectively.

TABLE XII. INOCULATION REACTIONS AFTER SECOND DIPHTHERIA PTINJECTION, SHOWING TYPE OF REACTION AND SEX OF PERSONS INOCULATED

Type of reaction

Mild local .......

Local .

Mild general ......

General

Mild local/mild general

Local/mild general .

Mild local/general

Local/general.

Total number of positivereactions.

Males Females

no. of % of total

reactions

75 75

14 14

6 6

0 0

0 0

1 1

3 3

1 1

75 100 100 100

969

10075 100 100


The reaction percentage after the second antigen injection is higherthan after the first: an average of 14.6% as against 11.8%. This appliesto the males as well as to the females. Moreover, it was found that noless than 11.9% of those who had not reacted to the first injection reactedpositively to the second inoculation. In this case, the higher percentagecannot be attributed to a different age distribution of the persons con-cerned; for, as shown by fig. 3, the reaction percentage increases more orless according to age, whereas the average age of those who were inocu-lated twice is lower than that of the persons who had only one inoculation.

We believe that this phenomenon can readily be attributed to thefirst Diphtheria PT injection having caused a sensitization to the diphtheriaantigen used in the vaccine. Whether the second injection of Schick toxinalso had a sensitizing effect, it is impossible to ascertain.

After the second antigen injection, as well as after the first, the femalesshowed a considerably higher reaction percentage than the males (anaverage of 18% as against 11.6%).

The 1,199 persons who were inoculated twice are arranged in table XIIIaccording to the combination of their reactions to the two injections. Asthis table shows, the total percentage of those who were inoculated twice andreacted differently to the two injections was 15.5%, 4.6% having reactedto the first, but not to the second injection.

TABLE XiII. REACTIONS AFTER FIRST AND SECOND DIPHTHERIA PTINJECTIONS

First Second Number of %injection injection cases

negative negative 969 80.8

positive positive 44 3.7

positive negative 55 4.6

negative positive 131 10.9

Total 1,199 100

Schick conversion-rates

Table XIV gives a tabulated summary of the conversion-rates found inthe second and the third Schick tests, i.e., after one inoculation and twoinoculations, respectively. As in earlier tables, " negative " stands for thecombinations-, - and ±, +; " positive " for the combinations ±,-,and + +, +. Of course, the very slight difference between the conversion-rate of the males and that of the females after the first inoculation has nosignificance.

970


TABLE XIV. SCHICK CONVERSION-RATES

Positive Negative reactions Negative reactionsreactions after 2nd Schick test after 3rd Schick testafter 1 stSchick no. of % of no. of % oftest cases total cases total

Total 1,199 997 83.2 1,196 99.7

Males 644 527 81.8 643 99.8

Females. 555 470 84.7 553 99.6

As this table shows, we found the Schick conversion-rate to be 83.2%after one inoculation and 99.7% after two inoculations. As pointed outearlier, the latter, very high, conversion-rate may, to some slight extent,also have been due to the intervening second Schick injection.

The three persons treated by us who still showed a positive reaction tothe third Schick injection were consequently inoculated for a fourth time.One month after this last injection they, too, showed a negative Schickreaction.

Reactions to first Schick test ofpersons with history of diphtheria

Of the persons treated by us, 204 stated that they had had diphtheriaat some earlier time. They were treated in exactly the same way as theother children and adults, but have not been included in the precedingtables and graphs, as we did not know to what extent their inoculationreactions and Schick conversion-rates might be influenced by their havinghad the disease.

According to Scheibel et al.,20 such people react more strongly to theMoloney test and may therefore be expected to show a somewhat strongerreaction to the inoculation too. However, this was not confirmed by ourresults. The children and adults who stated that they had had diphtheriadid not show any stronger inoculation reaction than the others of the sameage and sex who had never had the disease. As these persons are distributedover all age-groups, there would be little point in giving further details oftheir reactions.

On the other hand, the outcome of the first Schick test to which these204 persons were subjected is of considerable interest. These results areshown in table XV, where, once again, "negative" represents the combina-tions -, - and +, ±, and "positive" stands for the combinations +,-,and +-+F, +.

The results obtained lead to the following conclusion: Of all the personstreated by us who had had diphtheria at some earlier time, 12.7% stillshowed a positive Schick reaction.

971


Nakamura & Kaga12 found that the blood of many people who hadhad diphtheria at some time or other contained but little antitoxin. Extensiveanimal experiments led them to the conclusion that the fact of having haddiphtheria once does not generally cause any considerable formation ofantitoxin, and that a vigorous production of antitoxin is stimulated onlyby repeated infection (which may be subclinical).

TABLE XV. REACTIONS TO FIRST SCHICK TESTOF PERSONS WITH HISTORY OF DIPHTHERIA

PositiveTotal Avege Negative | of

n. total

Total ........... 204 13.6 178 26* 12.7

Males .......... 119 13.4 103 16 13.5

Females . . . . 85 14.3 75 10 11.8

History of diphtheria

5 years before, or less 68 9.8 60 8 11.8

6 years before, or more 98 19.4 86 12 12.2

date unknown 38 11.7 32 6 15.8

* Of the 26 persons who had shown a positive reaction to the first Schick test, 2 still reactedpositively to the second Schick test.

Hamburger & Siegl 6 found that 15 out of 20 diphtheria patients whohad recovered " spontaneously" (i.e., without being given a serum injec-tion) showed a positive Schick reaction immediately after their recovery.After from 4 to 12 months, 11 of these persons were subjected to a secondSchick test, the result in 7 cases still being positive.

The difference between the positive percentages for males and forfemales in table XV-13.5% and 11.8%-is not significant ; neither are thedifferences between the last three figures in column 6 of the same table,namely, 11.8%, 12.2%, and 15.8%. Probably, these differences are entirelydue to the different average age of the various categories.

But the average percentage of 12.7 deviates significantly from 0%.If one may attach any value to the result of the Schick test as an indicationof the immunity of the persons concerned, these 26 persons were notsufficiently immune to diphtheria. Even after one inoculation two of themwere still Schick-positive. All of them, therefore, were in great need ofimmunization.Results of immunity checks 12 and 24 months after immunization

As has been stated earlier, most of the children were immunized by us inthe course of the school year 1950-1. In order to get an idea of the dura-

972


bility of the immunity which we had obtained or which had been reinforced byone Diphtheria PT injection, these children were divided into two groups. Theimmunity of one group was tested (again) 12 months after the last negativeSchick reaction and the other group was examined for its immunity in thesame way 24 months after the last negative Schick reaction. The childrenof the first group who were found to react positively (to the first test) weregiven one injection of Diphtheria PT. During one of the regular immuniza-tion campaigns organized by the Zeist School Medical Service, the childrenof the second group all received one booster injection of Diphtheria PTafter their Schick reaction had been read.

The results of these tests are given in table XVI, where the children ofeach group are subdivided according to whether their first, second, or thirdSchick reaction was negative. In this table the children have not beendifferentiated according to sex, and " negative" stands for both ,-and+, ±, " positive " for both +, -, and +-+, +.

TABLE XVI. RESULTS OF IMMUNITY CHECKS 12 AND 24 MONTHS AFTERIMMUNIZATION

(A) After 12 months

Positive reactionsHistory of reactions Number to immunity checkHistory of reactions of persons

no. % of total

Negative to 1st Schick test 1,031 11 1.1

Negative to 2nd Schick test 234 2 0.9

Negative to 3rd Schick test 25 0 0

Total 1,290 13 1.0

(B) After 24 months

Positive reactions

History of reactions of persons to immunity checkof persons

no. % of total-

Negative to 1st Schick test 659 10 1.5

Negative to 2nd Schick test. 225 6 2.7

Negative to 3rd Schick test 18 0 0

Total . 902 16 1.8

Of course the differences between the test results found for children witha negative first-, second-, or third-Schick reaction (after being immunizedby us) are of no importance. What strikes one, however, is the very slight

973


reversion of the Schick reaction. Only 10% of all the children who wereSchick-negative after their immunization showed a positive reaction whenexamined twelve months later ; and this figure rose only to 1.8% in the caseof those who were not examined until 24 months later.

Inoculation-rates in Municipality of Zeist, 1 September 1951-31 August 1952and 1 September 1952-31 August 1953

Finally, we tried to get an idea of how many children of the age-groupsthat should properly have been inoculated or re-inoculated against diph-theria were actually treated by us or by the Municipal Public-HealthService of Zeist, restricting ourselves to the children under 13 years of age.

Generally speaking, these children can be divided into two groupsthose who come under the School Medical Service and those who do not.The latter group comprises the children under 3 and the 3-5- or 6-year-oldswho do not attend an infant school.

With respect to the former group the calculation was fairly simple.The school lists of the School Medical Officer (J.D.L.) gave the namesof all the children who might be suitably inoculated or re-inoculated, arrangedaccording to the form they were in ; it was also known (at the beginningof 1954) who among them had actually had a preventive injection againstdiphtheria in the periods mentioned. Some of the 3-6-year-olds were alsoto be found on these lists (infant schools) ; to these the same methodcould be applied.

A great number of young children (below the age of 6) were inoculatedagainst diphtheria, some by us (at the beginning of 1952), some by the staffof the Municipal Public-Health Service of Zeist, and some by L. H. Brandt, fthe Public-Health Officer detached for the hamlet of den Dolder by the Muni-cipal Public-Health Service of Zeist.

From the Municipal Registry of Zeist (of which municipality den Dolderis a part) we received returns of all the children who belonged to one ofthe following age-groups-under 1, 1-2, 2-3, 3-4, 4-5, or 5-6-during thetwo periods of our investigation, together with their birth dates. Duringeach of these two periods (1 September 1951 to 31 August 1952 and 1 Septem-ber 1952 to 31 August 1953) every child naturally became one year older.The registry returns always gave the initial age of the child, each childbeing counted only once in each period.

We then checked whether the child in question had been inoculatedbefore or after its birthday ; the real age-the years the child numberedat the moment when the diphtheria immunization was carried out-wasalways taken as the " immunization age ". If, therefore, a' child was vacci-nated against diphtheria after its birthday in either of the periods referred to,

f The authors would like to take this opportunity of thanking this colleague for the returns of the childreninoculated by him in the two periods.


we subtracted one from the total number of children in the age-group towhich the child belonged according to the registry returns (in other words,the children that might suitably be inoculated), and added one to the nextage-group (to which the child belonged in view of the date on which itwas inoculated).

Naturally, the children inoculated in the first period (1 September1951 to 31 August 1952) were excluded from inoculation in the second periodchosen (1 September 1952 to 31 August 1953). Their numbers, therefore,were subtracted from the numbers of children eligible for inoculation inthe second period.

Table XVII gives the results of these calculations for both periods.It should be noted that a number of the young children were not onlyinoculated against diphtheria, but also immunized against pertussis at thesame time (with Diphtheria-Pertussis PT).

TABLE XVII. INOCULATION-RATES IN MUNICIPALITY OF ZEIST,1 SEPTEMBER 1951 TO 31 AUGUST 1952, AND 1 SEPTEMBER 1952 TO 31 AUGUST 1953

1 September 1951 - 31 August 1952 1 September 1952 - 31 August 1953

Age- no. of vacntdno. of vciaegroups children in vaccinated children in vaccinated(years) need of need of

immuniza- no. % immuniza- no. %tion n.tionno

< 1 754 84 11.1 780 56 6.5

1 - 2 857 118 13.8 714 88 12.3

2 - 3 807 112 13.9 724 36 5.0

3 - 4 835 204 24.5 735 84 11.4

4 - 5 1,043 311 29.8 625 61 25.8

5 - 6 1,086 349 32.2 820 202 24.6

6 - 8 a 958 812 84.7 1,160 988 85.1

8 -1 0 b 747 629 84.2 839 719 84.6

10 -12 c 777 605 77.9 874 633 81.8

12 -13 d 762 585 76.8 803 567 70.6

Total 8,626 3,809 44.9 8,074 3,434 40.8

a First form of elementary schoolb Third form of elementary schoolc Fifth form of elementary schoold So-called "seventh school-year", i.e., first form of various types of secondary school

When judging the inoculation-rates shown in table XVII, two factsshould be taken into account. First, this voluntary inoculation was stimu-lated during the earlier period (1 September 1951 to 31 August 1952) byintensive propaganda, partly of a personal character, with a view to facili-tating our investigation. This stimulant was lacking during part of the

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second period. Secondly, it should be pointed out that there was a seriousepidemic of poliomyelitis in the Netherlands during the second period, inconsequence of which practically all prophylactic vaccinations were sus-pended from about 15 May to 15 November 1952. This has no doubthad an unfavourable effect on the immunization, especially of the lowerage-groups. Lastly, it should be added that the prophylactic inoculationsagainst diphtheria carried out personally by family doctors are not includedin these figures, as it was impossible to ascertain their number. However,these will not have been very numerous. Though the figures stated shouldtherefore be regarded as minimal rates, the real situation will not havediffered much from the figures given.

As a study of the figures in table XVII will show, the immunizationof the very young children especially (under 1, 1-2, and 2-3 years old)was quite insufficient. In the case of these children, who cannot be relatedto the Municipal Public-Health Service of Zeist in any form of organization,the prophylactic inoculation against diphtheria depends almost entirelyupon the activity of their parents.

In both periods the inoculation-rates of the 3-4- and 4-5-year-oldsalready show a more satisfactory level. This is not, however, due to anygreater activity on the part of the parents. This improvement is solelydue to the fact that a number of these children attended the infant schoolsand thus came into contact with the School Medical Service.

The figures found for the age-groups from 6 to 13 can certainly be calledsatisfactory. But here again the results are mainly due to the efforts of theSchool Medical Service and not to the activity of the parents.

General Discussion

As has already been pointed out, the composition of the group ofchildren and adults examined by us it not representative of the Dutchpopulation, especially with regard to the age distribution. This is particu-larly evident in the younger children and the adults. However, as thereis not any organized relation between these two categories and the SchoolMedical Service of Zeist, and as we had to make our investigation fit inwith the annual immunization campaigns, we could do very little to correctthese faults.

Attention has also been drawn to the fact that the quantitative resultsof our investigation are more or less specific for the period 1950-1, whenmost of the persons we examined were immunized by us, the reason for thisbeing that the immunity which is ultimately achieved is due not only tothe artificial immunization by means of Diphtheria PT injections but insome degree also to natural immunization.

How important this natural immunity may be under certain conditionsis shown in a recent publication by Rendu,18 who compares the diminishing

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diphtheria morbidity in Western Germany and Japan-countties in whichthere were no large-scale inoculation campaigns against diphtheria in theyears on which he based his observations (1944-52)-with the decreasingdiphtheria frequency in Canada, France, and " 19 other European coun-tries" (not further specified). Rendu concludes that the proportionaldecrease in morbidity in Western Germany and Japan in the period referredto (± 75%) equals the decrease in the countries adduced for comparison.This in itself is not unreasonable. It is quite conceivable that a populationwhich lives in very bad hygienic conditions (for example, considerableovercrowding), and which at a certain time (1944) had a very high absolutediphtheria-morbidity, will show a considerable relative decrease of thismorbidity solely on account of natural immunization. In this connexionreference may be made to a publication by Fenakel,3 in which the epi-demiology of diphtheria is treated in an exhaustive manner.

From his figures and graphs Rendu concludes-wrongly we believe-that large-scale inoculation campaigns against diphtheria are superfluous.In the fight against diphtheria, it is the absolute decrease in morbidity thatmatters. In countries like France and Canada-and one might alsoinstance England (see, for example, Logan 9) and Denmark-the very lowabsolute morbidity figures are certainly not entirely due to natural immuni-zation, but must, in our opinion, be largely ascribed to the effect of artificialimmunization.

We arrive at a similar conclusion in view of our own results. Whencomparing the reactions to the first Schick injection of people who had notbeen previously immunized against diphtheria and people who had, wefound about four times as many positive reactions among the former asamong those who stated that they had previously been immunized. Allowingfor the fact that the number of persons who stated that they had beeninoculated against diphtheria before was undoubtedly too great, ourinvestigation clearly demonstrated the existence of immunity caused byprevious immunizations.

The Schick reactions of the children and adults we examined showedthat the high proportion of positive first reactions found among the childrenunder one year old drops rapidly as the age rises, a minimum being reachedin the age-groups from 10 to 15. A marked increase then sets in in thesubsequent age-groups.

Of course, it must not be concluded from this that the susceptibilityto diphtheria of these older children and adults increases in the samedegree. Noordam14 has pointed out that about 80% or 90% of the popula-tion are naturally immune against diphtheria and that the inoculation ofthese persons would be superfluous.

We offer no opinion on the accuracy of Noordam's figures, but arequite willing to admit that the marked increase in the number of positivefirst-Schick reactions found with each higher age-group we examined need

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not necessarily imply a proportional increase of the susceptibility to diph-theria of the persons in question. Nevertheless, we think it our duty toemphasize the desirability of giving children over school age (12-18) oneor two more booster injections with Diphtheria PT whenever possible.

Edsall,2 Scheibel et al.,20 and Tudor Lewis 21 also draw attention to theincreasingly important problem of the prophylactic immunization againstdiphtheria of adults, especially in countries such as Canada, Denmark,and England, where intensive immunization campaigns have greatly reducedthe number of carriers, so that natural immunization is becoming a lessand less important factor in the maintenance of a reasonable level ofimmunity.

With regard to the ensuing inoculation reactions, we found that theseincreased in number as the persons concerned became older. At the sametime we found a considerable difference between the reactions of malesand of females, in that at practically every age the latter showed abouttwice as many reactions as the corresponding groups of the former. Wehave not yet been able to explain this curious fact.

Our results agreed with those of Danish investigators (Scheibel et al.20).With respect to the appreciation of the results, it may be observed that(as appeared later) our criteria practically conform to the definitions acceptedfor this purpose by the Conference of Heads of Laboratories ProducingDiphtheria and Pertussis Vaccines organized by WHO in Dubrovnik,Yugoslavia, in October 1952 (page 16 of report of the conference 22).

Ourjudgement of the inoculation reactions led us to the same conclusionas that formulated by Noordam et al.'5. In general, adults tolerated thevaccine very well. On the whole, the number of reactions may be said tohave been inconsiderable and reactions of a really unpleasant characterwere limited to exceptional cases.g

In this investigation, as in the investigations already referred to(Noordam et al.'5 and de Graaf et al.5), the immunizing effect of theprophylactic was judged by the so-called " Schick conversion rates ", i.e.,the proportional conversion of positive first Schick reactions to negativeSchick reactions. One month after the first Diphtheria PT injection wefound a Schick conversion-rate of 83.2%, the figure rising to 99.7% aftera second antigen injection.

Near the beginning of this article, and also in the discussion of table XIV,it was pointed out that this very high conversion-rate after two injectionsmay to some small extent have been favourably affected by the interveningsecond Schick injection which, theoretically, could have had a stimulatingeffect on antibody production. However, it was argued that it was very

g The use of Diphtheria PT also for adults can be recommended with all the more conviction as theNational Institute of Public Health, Utrecht, will shortly start producing this prophylactic with a reductionof the concentration of AlPO, from 10 mg to 5 mg per ml, without any loss of its good antigenic properties.This reduction in the amount of carrier (which is the function of the AlPO4) will no doubt further diminishthe number of unpleasant inoculation reactions.


unlikely that this phenomenon had played a part of any importance inour experiments.

In support of our argument, reference may once more be made to thepublication by Noordam et al.15, who found a Schick conversion-rate of98%-98.5% for 227 children whose first Schick reactions had been positiveand who had had two inoculations (with Diphtheria PT). These 227 childrenhad been given a Schick injection only before the first and after the secondinoculation, the so-called " intermediate Schick" having been omitted intheir case. A comparison of the Schick conversion-rate of 98%-98.5%found after their immunization with our figure of 99.7% will show that theimmunizing effect of this intermediate Schick must have been very slightindeed.

Of 204 persons, greatly varying in age, with a history of diphtheria atsome earlier time (mainly during the second World War), 12.7% were foundto react positively to the first Schick injection. If one may attach any valueto the result of the Schick test with respect to the immunity of the personstested, these 26 people consequently must have been insufficiently immuneto diphtheria. Even after one inoculation two of them were still Schick-positive, which proves that they were all in urgent need of immunization.

The practical conclusion to be drawn from this is that, in large-scaleimmunization campaigns, children and adults who state that they havehad diphtheria, and for that reason believe that they can do without anartificial immunization, nevertheless do need to be immunized.

We were able to examine 1,290 children 12 months after they had beenimmunized by us. On ascertaining their immunity by means of the Schicktest, we found a reversion-rate of only 1.0%. Another group, of 902 children,examined in the same way 24 months after their immunization, showed areversion-rate of only 1.8%.

We believe that these figures give a very favourable impression of theimmunity obtained or reinforced by the inoculations. It has been the regularpractice of the Municipal Public-Health Service of Zeist to ensure theprimary immunization of every child they treat by giving two Diphtheria PTinjections and to follow this up with one booster injection every two years.Our results provide a very good factual justification for this practice.

Finally, we tried to get an approximate idea of how many of the childrenthat might have had a prophylactic diphtheria vaccination were actuallyimmunized. For this purpose the inoculation-rates for several age-groupsduring the periods 1 September 1951 to 31 August 1952 and 1 September1952 to 31 August 1953 were calculated; table XVII shows the results.

It is an accepted truth (see, for example, the above-cited WHO report 22)that the immunization against diphtheria of large populations can bereally effective only if at least 75% of those in danger of infection areregularly inoculated and re-inoculated. Our investigation showed that atZeist this inoculation-rate is amply reached for those age-groups that are

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almost entirely under the supervision of the School Medical Service (the6-13-year-olds; inoculation-rate ± 80%). But of the age-groups immediatelypreceding these (the 3-6-year-olds), only those who attend the infant schoolsare immunized by the School Medical Service, and the inoculation-rateof these groups is already insufficient (±25%). Even worse, however, isthe state of immunization of the very susceptible year-groups from underI to 3, since, on an average, no more than about 12% of the children indanger of infection appear to be inoculated.

In this connexion, reference may be made to an article by Ruys,19 inwhich it is demonstrated how unfavourably the immunization of young(and very susceptible) children in the Netherlands compares with theresults obtained in other countries. The particularly impressive inoculation-rates in Denmark may be taken as an example. Bojlen 1 states that in theschool year 1950-1 they succeeded in giving 91.2% of the children notattending school (under the age of 6) their primary injections. On goingto school (first form) another 5.7% were inoculated, so that 96.9% of thepupils in the first form of the elementary schools had been inoculatedagainst diphtheria.

After a very detailed study of diphtheria in the Netherlands during thesecond World War, Hoogendoorn 7, 8 arrived at the following conclusion:

" On account of the good results of the vaccinations we may assume that the greatmajority of the more than 220,000 cases and of the about 13,000 deaths, notified in theyears 1940-1946, would have been prevented if the whole population or a great deal of ithad been artificially immunized on the first of January 1940. " (page 218 of Hoogendoorn 7)

Lastly, reference may once more be made to table III which showsthat in 1953 there were still 2,560 reported cases of diphtheria in the Nether-lands.

May this study aid the fight against this disease, which can certainly beeradicated

RESUME

Depuis 1949, l'Institut national de sante publique des Pays-Bas prepare un vaccinpour l'immunisation active contre la diphterie, sous forme d'anatoxine phosphatee (AP)hautement purifiee, contenant 1.500 Lf par mg d'azote proteinique. Des recherches etenquetes ont ete effectuees en 1950-51 et 1952-53, afin de preciser la valeur de ce vaccin,par l'immunisation d'ecoliers, d'enfants ne suivant pas l'ecole et d'adultes, dans unecommunaute des Pays-Bas. Les auteurs decrivent les methodes adopt&es et les resultatsobtenus au cours de cette etude qui a porte sur 4.272 personnes des deux sexes, deI i 70 ans, qui, apres avoir ete soumises au test de Schick, regurent en injection intra-musculaire 0,5 ml de AP.

La vaccination a donne des resultats tres favorables. Le vaccin a ete bien supporte,quoique des reactions a l'inoculation se soient parfois produites, plus frequentes dans lesgroupes d'age 6leves que chez les enfants. Dans tous les groupes d'age, pratiquement,les femmes presenterent des reactions nettement plus fortes que les hommes.

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La proportion de reactions positives au premier test de Schick 6tait elevee chez lesenfants de 0-4 ans, qu'il s'agisse de sujets ayant et vaccines anterieurement ou non.La proportion baissait de la quatrieme annee a la dixieme 'a la suite d'une immunisation<i naturelle)> due 'a des formes subcliniques de la maladie, puis s'elevait a nouveau jusqu'"ala quinzieme annee. Les auteurs estiment, en consequence, que les enfants ayant quittel'6cole primaire devraient recevoir, dans la mesure du possible, une ou deux injections derappel d'anatoxine diphterique.

Le taux de virage du Schick (TVS) 'a la suite de plusieurs injections a permis d'6valuerl'effet de la vaccination. II etait de 83,2 % apres la premiere injection et de 99,7 % apresla seconde.

Sur 204 personnes ayant eu la diphterie ant6rieurement, 12,7 % ont r6agi positivementau premier test de Schick. I1 est donc a conseiller de ne pas exclure de la vaccinationles sujets censes avoir eu la diphterie.

On a controle l'immunite dans deux groupes d'enfants vaccines, comprenant l'un1.290 et l'autre 902 sujets, respectivement 12 et 24 mois apres le dernier test de Schicknegatif. Le taux de reversion a la positivite a ete tres satisfaisant, ne depassant pas 1,0 %dans le premier groupe et 1,8 % dans le second.

Les auteurs ont cherche a se faire une idee du #taux d'inoculation #, c'est-'a-direla proportion de sujets immunises dans des groupes d'age donnes de la population.Ce taux est excellent (environ 80 %) dans les groupes d'age qui sont sous la surveillancedu service medical scolaire. I1 est loin d'etre satisfaisant (n'6tant que de 25 % environ)dans les groupes d'age inferieurs, oii seuls les enfants suivant l'ecole enfantine sontvaccines. La situation est pire encore dans les groupes d'age particulierement sensibles(1-3 ans) oii 12 % seulement des enfants sont vaccines. Cette proportion est de beaucoupinferieure a celle que l'on observe dans d'autres pays, au Danemark par exemple.

REFERENCES

1. Bojlen, K. (1952) Rev. Immunol. (Paris), 16, 2742. Edsall, G. (1952) Amer. J. publ. Hlth, 42, 3933. Fenakel, E. (1953) Ein Beitrag zur Epidemiologie der Diphtherie im zwanzigsten

Jahrhundert, Basel4. Fraser, D. T. (1931) Trans. roy. Soc. Can., Sect. V, 25, 1935. Graaf, J. F. H. de, Tasman, A. & Brandwijk, A. C. (1950) Ned. T. Geneesk. 94, 28966. Hamburger, F. & Siegl, J. (1929) Munch. med. Wschr. 76, 15377. Hoogendoorn, D. (1948) Over de diphtherie in Nederland; epidemiologie en pro-

phylaxe (Thesis, Utrecht)8. Hoogendoorn, D. (1949) Ned. T. Geneesk. 93, 31539. Logan, W. P. D. (1952) Monthly Bull. Minist. Hlth (Lond.), 11, 50

10. Moloney, P. J. & Fraser, C. J. (1927) Amer. J. publ. Hlth, 17, 102711. Moloney, P. J. & Fraser, C. J. (1928) Ann. Inst. Pasteur, 42, 142012. Nakamura, B. & Kaga, N. (1952) Keijo J. Med. 1, 283. Abstracted in Bull. Hyg.

(Lond.), 1954, 29, 1513. Netherlands, Centraal Bureau voor de Statistiek (1953) Statistisch Zakboek, Den

Haag14. Noordam, A. L. (1953) Ned. T. Geneesk. 97, 88615. Noordam, A. L., Brandwijk, A. C., Tasman, A. & Timmerman, W. Aeg. (1949)

Ned. T. Geneesk. 93, 401416. Pappenheimer, A. M., jr. & Lawrence, H. Sherwood (1948) Amer. J. Hyg. 47, 24117. Ramon, G. (1924) Ann. Inst. Pasteur, 38, 118. Rendu, R. (1953) Lyon med. 34, 113, 297


19. Ruys, A. C. (1954) Ned. T. Geneesk. 98, 110420. Scheibel, I., Tulinius, S. & Bojl6n, K. (1949) Acta path. microbiol. scand. 26, 57721. Tudor Lewis, J. (1954) Med. Offr, 91, 1722. World Health Organization, Conference of Heads of Laboratories Producing

Diphtheria and Pertussis Vaccines (1953) Wld Hith Org. techn. Rep. Ser. 61

RESULTS DIPHTHERIA PHOSPHATE TOXOID

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