Revealing Measles Outbreak Risk With a Nested Immunoglobulin G Serosurvey in Madagascar

Amy Winter (1) , Amy Wesolowski (1) , Keitly Mensah (2) , Miora Bruna Ramamonjiharisoa (3) , Andrianmasina Herivelo Randriamanantena (3) , Richter Razafindratsimandresy (3) , Simon Cauchemez (4) , Justin Lessler (1) , Matt J Ferrari (5) , C Jess E Metcalf (2) , Jean-Michel Heraud (3)

1 Johns Hopkins Bloomberg School of Public Health [Baltimore]
2 Princeton University
3 IPM - Unité de Virologie [Antananarivo, Madagascar]
4 Modélisation mathématique des maladies infectieuses
5 Penn State - Pennsylvania State University

Madagascar reports few measles cases annually and high vaccination campaign coverage. However, the underlying age profile of immunity and risk of a measles outbreak is unknown. We conducted a nested serological survey, testing 1,005 serum samples (collected between November 2013 and December 2015 via Madagascar's febrile rash surveillance system) for measles immunoglobulin G antibody titers. We directly estimated the age profile of immunity and compared these estimates with indirect estimates based on a birth cohort model of vaccination coverage and natural infection. Combining these estimates of the age profile of immunity in the population with an age-structured model of transmission, we further predicted the risk of a measles outbreak and the impact of mitigation strategies designed around supplementary immunization activities. The direct and indirect estimates of age-specific seroprevalence show that current measles susceptibility is over 10%, and modeling suggests that Madagascar may be at risk of a major measles epidemic.

Mots clés: Madagascar; measles; rubella; serological survey; surveillance; surveillance Abbreviations: IgG; Immunoglobulin G; SIA; supplementary immunization activities; WHO; World Health Organization

Domaines: Santé publique et épidémiologie

Amy Winter, Amy Wesolowski, Keitly Mensah, Miora Bruna Ramamonjiharisoa, Andrianmasina Herivelo Randriamanantena, et al.. Revealing Measles Outbreak Risk With a Nested Immunoglobulin G Serosurvey in Madagascar. American Journal of Epidemiology, 2018, 187 (10), pp.2219 - 2226. ⟨10.1093/aje/kwy114⟩. ⟨pasteur-01920183v2⟩