Field evaluation of measles vaccine effectiveness among children in the Democratic Republic of Congo.
BACKGROUND
Large-scale measles outbreaks in areas with high administrative vaccine coverage rates suggest the need to re-evaluate measles prevention and control in the Democratic Republic of Congo (DRC). Monitoring of measles Vaccine Effectiveness (VE) is a useful measure of quality control in immunization programs. We estimated measles VE among children aged 12-59 months in the Democratic Republic of Congo (DRC) using laboratory surveillance data from 2010-2012.


METHODS
We used the case-based surveillance system with laboratory confirmation to conduct a case-control study using the test negative design. Cases and controls were selected based on presence (n=1044) or absence (n=1335) of measles specific antibody IgM or epidemiologic linkage. Risk factors for measles were assessed using unconditional logistic regression, stratified by age.


RESULTS
Among children 12-59 months, measles vaccination was protective against measles [aOR (95%C)], 0.20 (0.15-0.26) and estimated VE was 80% (95% CI 74-85%). Year of diagnosis, 2011: 6.02 (4.16-8.72) and 2012; 8.31 (5.57-12.40) was a risk factor for measles when compared to 2010. Compared to Kinshasa, children in Bas-Congo, Kasai-Oriental, Maniema and South Kivu provinces all had higher odds of developing measles. Measles VE was similar for children 12-23 months and 24-59 months (80% and 81% respectively).


CONCLUSIONS
Repeated occurrences of measles outbreaks and lower than expected VE estimates suggest the need to further evaluate measles vaccine efficacy and improve vaccine delivery strategies in DRC.
Department of Epidemiology, UCLA Fielding School of Public Health, 650 S Charles E Young Drive, Los Angeles, CA 90095, USA. Electronic address: rhdoshi@ucla.edu.
Reena H
RH
Doshi
Department of Microbiology, Kinshasa School of Medicine, B.P. 127 Kinshasa, Lemba, Kinshasa, Democratic Republic of the Congo. Electronic address: patrickmukadi@gmail.com.
Patrick
P
Mukadi
Expanded Programme on Immunization, Ave de la Justice, Kinshasa, Democratic Republic of the Congo. Electronic address: shidicalixte5@yahoo.fr.
Calixte
C
Shidi
Expanded Programme on Immunization, Ave de la Justice, Kinshasa, Democratic Republic of the Congo. Electronic address: audrymwk@hotmail.fr.
Audry
A
Mulumba
Department of Epidemiology, UCLA Fielding School of Public Health, 650 S Charles E Young Drive, Los Angeles, CA 90095, USA. Electronic address: Nhoff84@ucla.edu.
Nicole A
NA
Hoff
Polio Program, Bill and Melinda Gates Foundation, 500 Fifth Avenue North, Seattle, WA 98109, USA. Electronic address: Sue.gerber@gatesfoundation.org.
Sue
S
Gerber
Kinshasa School of Public Health, B.P. 127 Kinshasa, Lemba, Kinshasa, Democratic Republic of the Congo. Electronic address: okitow@yahoo.fr.
Emile
E
Okitolonda-Wemakoy
Division of Disease Control, Ministry of Public Health, Ave de la Justice, Kinshasa, Democratic Republic of the Congo. Electronic address: kebelailunga@gmail.com.
Benoit Kebela
BK
Ilunga
National Institute for Biomedical Research, Minister of Public Health, Avenue de la Democratie, Kinshasa, Democratic Republic of the Congo. Electronic address: muyembejj@gmail.com.
Jean-Jacques
JJ
Muyembe
Department of Epidemiology, UCLA Fielding School of Public Health, 650 S Charles E Young Drive, Los Angeles, CA 90095, USA. Electronic address: arimoin@ucla.edu.
Anne W
AW
Rimoin
D016022:Case-Control Studies; D002675:Child, Preschool; D015023:Democratic Republic of the Congo / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D008297:Male; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage / Q000276:immunology*; D012307:Risk Factors; D016896:Treatment Outcome
D007075:Immunoglobulin M; D008458:Measles Vaccine
Democratic Republic of Congo; Immunization; Measles; Vaccine effectiveness; Vaccine preventable diseases