Polio immunity and the impact of mass immunization campaigns in the Democratic Republic of the Congo

Vaccine
Volume 35, Issue 42, Pages 5511-5730 (9 October 2017)
www.sciencedirect.com/science/journal/0264410X/35/41?sdc=1

Polio immunity and the impact of mass immunization campaigns in the Democratic Republic of the Congo
Original Research Article
Pages 5693-5699
Arend Voorman, Nicole A. Hoff, Reena H. Doshi, Vivian Alfonso, Patrick Mukadi, Jean-Jacques Muyembe-Tamfum, Emile Okitolonda Wemakoy, Ado Bwaka, William Weldon, Sue Gerber, Anne W. Rimoin
Abstract
Background
In order to prevent outbreaks from wild and vaccine-derived poliovirus, maintenance of population immunity in non-endemic countries is critical.
Methods
We estimated population seroprevalence using dried blood spots collected from 4893 children 6–59 months olds in the 2013–2014 Demographic and Health Survey in the Democratic Republic of the Congo (DRC).
Results
Population immunity was 81%, 90%, and 70% for poliovirus types 1, 2, and 3, respectively. Among 6–59-month-old children, 78% reported at least one dose of polio in routine immunization, while only 15% had three doses documented on vaccination cards. All children in the study had been eligible for at least two trivalent oral polio vaccine campaigns at the time of enrollment; additional immunization campaigns seroconverted 5.0%, 14%, and 5.5% of non-immune children per-campaign for types 1, 2, and 3, respectively, averaged over relevant campaigns for each serotype.
Conclusions
Overall polio immunity was high at the time of the study, though pockets of low immunity cannot be ruled out. The DRC still relies on supplementary immunization campaigns, and this report stresses the importance of the quality and coverage of those campaigns over their quantity, as well as the importance of routine immunization.