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