IMMUNIZATIONS

DEFINITION

• Immunization is the process of inducing immunity artificially by either vaccination

( active immunization ) or administration of antibody ( passive immunization ).

• ACTIVE IMMUNIZATION• Stimulates immune system to produce antibodies

and cellular immune responses that protect against infectious agent.

PASSIVE IMMUNIZATION

• Provides temporary protection through administration of exogenously produced antibody such as immune globulin.

• Also occurs naturally through transplacental transmission of antibodies to a fetus.

• Vaccine: A product of weakened or killed microorganism (bacterium or virus) given for the prevention or treatment of infectious diseases

• Toxoid : A modified bacterial toxin that has been made nontoxic but retains the capacity to stimulate the formation of antitoxin.

The major constituents of vaccines1. Active immunizing agent

Single antigen : tetanus , diphtheria toxoid Complex antigens : live viruses,killed bacteria

2. Suspending fluid Sterile water or saline Tissue culture fluid : egg Ag, gelatin

3. Preservatives , stabilizers , antibioticsAdded to prevent bacterial growth / stabilize AgThiomersol : mercurial subs. Neomycin , streptomycin

4. Adjuvants

• Aluminium salt added to enhance immune

• response

• Esp. vaccines with inactive microorgs

• eg. Hep B , Diph Tet toxoids

VACCINES ON SCHEDULE

1. Hep B : Hepatitis B( inactivated recombinant)

2. DTaP : Diphtheria & Tetanus toxoid and

acellular pertussis vaccine ( inactive)

3. DT & Td.: Diphtheria & Tetanus toxoid

4. Hib : Haemophilus influenzae b

Polysaccharide protein conjugate

5. IPV : Inactivated poliovirus vaccine

6. PCV7 : Pneumococcal conjugate vaccine

7. 23PS : Pneumococcal polysaccharide

8. MMR : Measles mumps rubella live vaccine

9. Varicella : Chicken pox live vaccine

10. Influenza : Inactivated vaccine

11. Hepatitis A : Inactivated vaccine

Simultaneous Administration

General RuleThere are no contraindications to simultaneous administration of any vaccines.

CombinationTwo live injected

All other

Minimum Interval4 weeks

None

Spacing of vaccine combinations not given simultaneously

Interference Between Live Virus Vaccines Separated by <28 days

• Retrospective cohort study of 115,000 children vaccinated in 2 HMOs during January 1995 through December 1999

• Risk of breakthrough varicella 2.5 times higher if varicella vaccine given <30 days following MMR

• No increased risk if varicella vaccine given simultaneously or >30 days after MMR

MMWR 2001;50(47):1058-61

Intervals Between Doses

General RuleIncreasing the interval between doses of a multi-dose vaccine does not diminish the effectiveness of the vaccine.

Decreasing the interval between doses of a multi-dose vaccine may interfere with antibody response and protection.

Minimum Intervals and Ages

Vaccine doses should not be given at intervals less than the minimum intervals or earlier than the minimum age

Violation of Minimum Intervals or Minimum Age

• ACIP recommends that vaccine doses given up to four days before the minimum interval or age be counted as valid

• Immunization programs and/or school entry requirements may not accept all doses given earlier than the minimum age or interval

Extended Interval Between Doses

• Not all permutations of all schedules for all vaccines have been studied

• Every study of extended intervals have shown no significant difference in final titer

• It is not necessary to add doses or restart the series because of an extended interval between doses

Vaccine Adverse Reaction• Adverse reaction

– extraneous effect caused by vaccine

– "side effect"

• Adverse event– any event following a vaccine– may be true adverse reaction– may be only coincidental

Vaccine Adverse Reactions

• Local– pain, swelling, redness at

site of injection– common with inactivated

vaccines– usually mild and self-limited

Vaccine Adverse Reactions

• Systemic– fever, malaise, headache– nonspecific– may be unrelated to vaccine

Live Attenuated Vaccines

• Must replicate to produce immunity

• Symptoms usually mild

• Occur after an incubation period(usually 7-21 days)

Vaccine Adverse Reactions

• Allergic– due to vaccine or vaccine

component– rare– risk minimized by screening

Contraindication

• A condition in a recipient which greatly increases the chance of a serious adverse event.

Precaution

• A condition in a recipient which may increase the chance or severity of an adverse event, or

• May compromise the ability of the vaccine to produce immunity.

Contraindications and Precautions

• severe allergy to a prior dose of vaccine or to a vaccine component

• encephalopathy following pertussis vaccine

Permanent contraindications to vaccination:

Contraindications and Precautions

ConditionAllergy to ComponentEncephalopathyPregnancyImmunosuppressionSevere illnessRecent blood product

LiveC---CCPP

InactivatedCCVVPV

C=contraindication P=precaution V=vaccinate if indicated

Invalid Contraindications to Vaccination

• Mild illness• Antibiotic therapy• Disease exposure or convalescence• Pregnancy in the household• Breastfeeding• Premature birth• Allergies to products not in vaccine• Family history unrelated to immunosuppression• Need for TB skin testing• Need for multiple vaccines

Invalid ContraindicationsMinor Illness

• Low grade fever• Upper respiratory infection• Otitis media• Mild diarrhea

• Only one small study has suggested decreased efficacy of measles vaccine in children with URI

• Findings not replicated by multiple prior and subsequent studies

• No evidence of increased adverse reactions

Screening Questions

• Allergies to food or medication?

• How is your child today?

• Any problem after last shots?

Screening Questions

• Problems with immune system

• Anyone in household with immune problems?

• Blood products in last year?

• Pregnant?

SPECIAL HOSTS

• IMMUNOCOMPROMISED

• Live vaccines are contraindicated

• Inactivated vaccines given per schedule

HOUSEHOLD CONTACTS

• Give MMR

• Vaccine virus is not transmitted

• Varicella also given

• Transmission of vaccine virus rare

• Disease if it develops is mild

Immunosuppression

• >20 mg per day if wt >10 kg

• >2 mg/kg per day

• NOT aerosols, topical, alternate day, short courses

Corticosteroids

Recommendations for Routine Immunization of HIV-infected Children

VaccineVaricellaMMRAll others

AsymptomaticYesYesYes

SymptomaticNoNoYes

Yes=vaccinate No=do not vaccinateYes=vaccinate No=do not vaccinate

PATIENTS TREATED WITH IG / BLOOD PRODUCTS

• Depends on dose

• MMR / Varicella give at suggested intervals

PRETERM INFANTS

• Immunize per chronologic age

• Use regular vaccine dosage

• Exception Hepatitis B vaccine

PREGNANCY OF RECEPIENT

• Live viral vaccines are contraindicated

• Theoretical risk to fetus

• No cases actually observed with congenital rubella or varicella

• Termination of pregnancy is not routinely indicated

PREGNANCY OF MOTHER OR OTHER

HOUSEHOLD CONTACT

• √ MMR vaccine : Vaccine virus not

• transmitted

• √ Varicella vaccine : Vaccine virus transmitted

• Frequency rare

• Mild / Asymptomatic infection

RECEPIENT IS BREASTFEEDING

• No vaccine is contraindicated

• Only rubella vaccine virus isolated from human milk.

EGG ALLERGIES

• MMR vaccine can be given without prior skin testing

• Influenza contraindicated if immediate hypersensitivity reaction to eggs

Vaccine Minimum age for first dose

Minimum age from dose to dose

Vaccine Minimum age for first dose

Minimum age from dose to dose

2 to 3 3 to 4

DTaP 6 WKS 1 MONTH 1 MONTH 6 MONTHS

Hib 6 WKS 1 MONTH 1 MONTH 2 MONTHS

PCV7 6 WKS 1 MONTH 1 MONTH 2 MONTHS

IPV 6 WKS 1 MONTH 1 MONTH 1 MONTH

MMR 12 MONTHS 1 MONTH

HBV BIRTH 1 MONTH 2 MONTHS

VARICELLA 12 MONTHS 1 MONTH

• Alex is a 1 month 25 day old infant who received his Hepatitis B #1 at birth and is here for a well visit. Is he due for any shots and can he get them today ?

• 2 month visit :

• DTaP#1 Hib#1 IPV #1 PCV7#1

• Does he have to return in 5 days for these?

• Can he get HBV #2 today ?

• Alex comes back for a sick visit at age 2 months 20 days.( 25 days later) He has a stuffy nose and is coughing with an axillary temperature of 99 F.

• Can he get his DTaP #2, Hib # 2, IPV #2 and HBV #3 today ? Mom is keen on getting them as it will save her an extra trip.

4 month visit

• DTaP # 2

• Hib # 2

• IPV# 2

• PCV7 # 2

• Alex comes back at age 4 months. His mother reported that his thigh was red and swollen after his previous shots.

• There is a strong family history of allergies including penicillin allergy. His older brother Josh had a “ bad” reaction after DTaP.

• Josh’s whole leg had swelled up and he had run a high fever too. Can Alex still get his shots ?

ADVERSE REACTIONS to DTaP

• Minor

• 2° to pertussis component

– Redness edema pain induration at inj site

– drowsiness fussiness crying

– Anorexia vomiting

– slight to moderate fever

MINOR REACTIONS

– Usually occurs within several hours

– of immunization

– Subsides spontaneously without

– sequelae

– Much less common with DTaP than

– DTP

– NOT CONTRAINDICATIONS

ALLERGIC REACTION

• Anaphylaxis: 2 cases per 100,000 • IS A CONTRAINDICATION• Transient urticarial reactions• Not anaphylactic ( IgE ) unless seen within

minutes• Serum sickness reaction• Unlikely to recur• NOT A CONTRAINDICATION

Contraindications to DTaP

• 1. Immediate anaphylaxis to vaccine

• 2. Encephalopathy within 7 days

• Coma , decreased conciousness prolonged sx

• 3. Progressive neurologic disorder

• infantile spasms, progr. encephalopathy

• uncontrolled sx

PRECAUTIONS

• These conditions may increase chance of adverse events

• Do not cause permanent sequelae

• Weigh risk versus benefit

• Community outbreak, foreign travel

PRECAUTIONS for DTaP

• 1. Seizure ± fever within 3 days of DTaP• Incid 1 in 1750 for DTP• 2. HHE or hypotonic-hyporesponsive

episode : Collapse or shock like state within 48 hrs

• Incid 1 in 1750 for DTP• 3. Fever >= 40.5 C ( 104.8 F ) within 48

hrs. Incid 0.3%

PRECAUTIONS for DTaP

• 4. Persistent severe inconsolable screaming / crying for three or more hours within 48 hrs.

DTaP NOT CONTRAINDICATED

• F/H of Seizures

• F/H of SIDS

• F/H of adverse reactions to DTaP

• Stable neuro conditions

• CP, well controlled sx, develop delay

• Hx of PCN allergy ,relatives with allergy

IN PERSPECTIVE

• DISEASE

• Diphtheria

• Death 1 in 20

• Tetanus

• Death 3 in 100 Pertussis

• Pneumonia 1 in 8 Encephalitis 1 in 20 Death 1 in 200

• VACCINE

• Continous crying with

• full recovery 1 in 100

• Convulsions or shock then full recovery

• 1 in 1750

• Acute encephalopathy

• 0-10.5 in 1,000,000

• Death none proven

• Alex comes back at 6 months for a well visit. What shots does he need ?

• 6 MONTHS

• Hep B # 3 ( Min age 6 mo & 4mo after 1st )

• DTaP # 3

• Hib # 3

• IPV # 3

• PCV7 # 3

• Alex will be 1 year old tomorrow. Mom does not want to give him shots on his birthday so can he get them today?

• Also she has heard that MMR has egg in it and he breaks out with hives when he eats eggs. Can he get the MMR ?

• 1 YEAR OLD

• Hib # 4 ( Min age 1 yr ;2 mo after 3rd dose)

• MMR # 1 ( Min age 1 yr )

• Varicella ( Min age 1 yr )

• PCV7 # 4 ( 2 mo after 3rd dose )

• Live attenuated

• Measles & Mumps : Chick embryo cell culture

• Does not have significant egg white

• ( ovalbumin ) cross reacting protein

• Rubella : Human diploid cell culture

MMR Vaccine

ADVERSE EVENTS

• MINOR ( after 7-12 days )

• 1. Fever >= 39.4 C ( 103 F )

• Lasts 1-5 days

• O/w Asymp

• 5-15 %

• 2. Transient rash 5%

ADVERSE EVENTS

• Moderate to severe• 1. Febrile seizures• Simple feb sx• Not at increased risk of epilepsy• 2. Transient thrombocytopenia• 2-3 weeks after ( upto 2 months ) • 1 in 25,000 – 1 in 40,000• Past/H of tcytopenia / vaccine tcytopenia• 3. Encephalitis / Encephalopathy < 1 in million

CONTRAINDICATIONS

• 1. Anaphylaxis to prior vaccine

• 2. Anaphylactic neomycin or gelatin allergy

• 3. Pregnancy

• 4. Immunocompromised states

• Alex returns for his 15 month check up.

• Mom says that he broke out with chicken pox 3 weeks after his last set of shots.

• She was worried because her nephew who has leukemia was staying with them at the time.

VARICELLA

• MISCONCEPTIONS

• 1. Chicken pox is a mild disease

• FACT 10,000 Hospitalizations and 100 deaths / year

• 2/3 rds the admissions and half the deaths occur in children

• Most imp risk factor for invasive GAStrep

• 2. Vaccine is not very effective• FACT : 85-90 % effective during outbreaks• 100% effective agnst severe disease• Mild varicella like illness in 1-4% of immunized

kids with rapid recovery• Rash so mild that it may resemble insect bites• Child is potentially infectious

• 3. Immunity does not last lifelong

• FACT Protection for at least 11 years in US and 20 years in Japan

• Other live viral vaccines : Immunity lasts a lifetime

• 4. Is it a safe vaccine ? • YES Reactions are mild• Minor inj site 20%• Local rash 3-5 %• Gen varicelliform rash after 5-26 days in• 3-5 %• Zoster like illness 2.6 / 100,000 vaccine • doses distributed

• 15 MONTHS – 18 MO

• DTaP # 4

• 4-6 YEARS ( PRE KINDERGARTEN )

• DTaP # 5

• IPV # 4

• MMR # 2

• 11 yrs

• Td

• Booster every 10 yrs

TAKE HOME MESSAGES

• Vaccines are safe• Vaccines are very effective• Educate yourself so that you do not propagate

misconceptions• Ask yourself “ Is the child more likely to die of

the vaccine or the disease?” before you with hold any vaccines

• Threat from vaccine preventable diseases is real

• Vaccination is one of the greatest achievements of medicine

• It has spared millions of people the effects of devastating disease