Post on 17-Mar-2016
description
The Médecins sans frontières experience in measles outbreak
response
Rebecca Freeman GraisMarch 16, 2011
Outline
• Brief background• Guidelines• Three recent examples, three different
experiences1. Maroua, Cameroon 2. N’djamena, Chad3. Malawi
• Ways forward
Background (I)
• Missions in 32 African countries• Vaccination
– Support in primary care when relevant– Outbreak response– Case management
• MSF vaccinated against measles– 1.5 million persons in 2009– > 4.5 million persons in 2010
• Frustrating field reality
Backgound (II): Duration of epidemics, reported cases and timing of interventions
2009
2005
2005
2004
2003
53000 +
8015
40857
2505
10880
Burkina Faso
N’Djamena, Tchad
Kinshasa, DRC
Adamawa, Nigeria
Niamey, Niger
Reported cases
Duration (months)YearPlace1 6 12+
Background (III): Burden of disease in pockets of high endemicity
Difficult to reach populations
High birthrates Insufficient vaccination
coverage Morbidity and mortality
burden CFR of 7% in rural areas
Proportion cases prevented by intervention coverage and time: 6 to 59m, Niamey, Niger
0
10
20
30
40
50
60
70
80
90
100
30 40 50 60 70 80 90 100
Intervention Coverage (%)
Prop
ortio
n of
Cas
es P
reve
nted
(%)
2 months 3 months4 months + 6 months
Source: Grais et al, 2007
Proportion cases prevented by intervention coverage and time: 6 to 15y, Niamey, Niger
0
10
20
30
40
50
60
70
80
90
100
30 40 50 60 70 80 90 100Intervention Coverage (%)
Prop
ortio
n of
case
s pre
vent
ed (%
)
2 months 3 months
4 months
Source: Grais et al, 2007
New WHO guidelines (March 2009)
• There is time and benefit to intervening
• Vaccination– Immediate selective
vaccination (6m to 5y) – District level outbreak
management team– decision about whether
non-selective mass campaign needed
Next step is to evaluate and further improve on recent gains and prevent
them from slipping
020
4060
8010
0ca
ses
0 5 10 15 20 25 30 35 40 45 50 2 7 12 17week
1. Maroua, Cameroun 2008-2009 (872 cases)
• Jan – May 2008– 39 cases
– Renforce EPI
October 2008 Increase in cases Campaign 6 to 59
months for certain wards
29 Jan. – 4 Feb. 2009 MoH mass campaign 6 mo to 15 years Free treatment (MSF)
1. Vaccine coverage survey, Maroua, Cameroon, April 2009 (n=3,025)
• Vaccination coverage of mass campaign estimated at 90%
• Number of doses received among children 6-59 months– 7% unvaccinated– 25% 1 dose– 47% 2 doses– 21% 3 doses
Source: Luquero et al, JID, in press
1. Lessons learned from Maroua outbreak
• Risk-assessment and interventions followed the guidelines
• Close cooperation between MoH, WHO and MSF
• Cases subsided but strategy still missed children
2. Measles epidemics in Ndjamena, Chad
• Rare context of subsequent interventions in the same city (2005, 2010)
• LQAS surveys to estimate coverage, before and after interventions– 2005 non-selective mass campaign (6-59m)– 2010 non-selective mass campaign (6m – 15y)
2. Reported cases, Ndjamena, Chad, 2005 and 2010
0
250
500
750
1 4 7 10 13 16 19 22 25
Weeks (2005)
Rep
orte
d M
easl
es C
ases
0
250
500
750
1000
1250
1500
1 4 7 10 13 16 19Weeks (2010)
Rep
orte
d M
easl
es C
ases
N=8481, AR = 54.5 per 10,000 N=7822, AR = 64.6 per 10,000
Campaign Campaign
survey
survey
2. Vaccination coverage before and after campaign (6-59 m), Ndjamena, Chad
BeforeCampaign
AfterCampaign
2005 2010 2005 2010
Card % (95% CI) 7.6 (6.3-8.9)
5.5 (4.1-5.6)
53.0 (50.6-55.4)
40.2 (36.9-43.5)
Card/Recall % (95% CI)
33.0 (30.9-35.1)
68.7 (66.7-70.7)
80.6 (78.6-82.6)
81.1 (79.8-82.4)
Source: Guerrier et al, Trop Med Int’l Health, in press
2. Lessons learned, N’djamena, Chad
• Intervention earlier, but still late• Chronically low vaccine coverage
– Failure to reach older children through routine services – Measles-susceptibles built up and led to the 2010
epidemic• 18% received their first dose in 2010
– previously vaccinated children were easier to reach during the outbreak than unvaccinated children
3. Measles cases and coverage 1997 -2009, Malawi
0
2 000
4 000
6 000
8 000
10 000
12 000
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Years
Mea
sles
Cas
es
0
10
20
30
40
50
60
70
80
90
100
Vacc
ine
Cove
rage
(%)
cases coverage
Source: Malawi MoH
Next SIA planned for 2011 for 6-59 months old
SIA’sSIA’s
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35
Week
Num
ber o
f Cas
es
3. Weekly distribution of measles cases in Malawi, week 1 to week 35, 2010
N=118.173, AR=847 per 100.000, CFR=0.2%Only ~250 deaths reported, 28/28 districts
NB: 25% of districts with no report for week 32, 50% for week 34
3. Weekly incidence in districts vaccinated by MSF, Malawi 2010
0
20
40
60
80
100
120
140
1 3 5 7 9 11 13 15 17 19 21 23 25 27 2 31 33 35Week
AR p
er 1
0000
0
Blantyre
Chiradzulu
Mzimba
Lilongwe
93.1 [90.9-95.2]
98.0 [97.4-98.6]
96.6 [95.6-97.6]
96.4 [95.0-97.9]
Reported measles cases & attack rates by region, sex and age group, Malawi 2010
Cases reported (%) AR per 100
Total Malawi 132653 (100%) 0.95
Northern region 4963 (4%) 0.28
Central region 64590 (49%) 1.09
Southern region 63100 (48%) 1.01
Sex 105209 (100%) 0.75
Male 53795 (51%) 0.77
Female 51414 (49%) 0.74
Age groups 128403 (100%) 0.92
0-5 months 7072 (6%) 2.20
6-8 months 10296 (8%) 7.38
9-11 months 7360 (6%) 4.40
12-59 months 28144 (22%) 1.35
5-14 years 39051 (30%) 1.00
15-19 years 13362 (10%) 0.98
≥20 years 23118 (18%) 0.39
3. Lessons learned from Malawi• Accumulation of susceptible individuals
– No large outbreak in 12 years– Outbreaks in the nineties of smaller scale– Vaccine effectiveness study found under 90% for EPI – High routine coverage but likely under 95%– Reduction immunity over time – Apostolic communities
• Under estimation of the epidemic risk
Source: Minetti et al, in press
Ways forward • EPI
– possibility for catch up > 11 months• SIA
– Strategies to adapt the changing epidemiology of measles
• Flexible age range• Interval between campaigns
• Outbreak response – Increased communication about
new guidelines and importance of prompt response
– Need for planning for outbreak response in budget
• Evaluations