RESUMEN
Background: Control efforts for measles and rubella are intensifying globally. It becomes increasingly important to identify and reach remaining susceptible populations as elimination is approached. Methods: Serological surveys for measles and rubella can potentially measure susceptibility directly, but their use remains rare. In this study, using simulations, we outline key subtleties in interpretation associated with the dynamic context of age-specific immunity, highlighting how the patterns of immunity predicted from disease surveillance and vaccination coverage data may be misleading. Results: High-quality representative serosurveys could provide a more accurate assessment of immunity if challenges of conducting, analyzing, and interpreting them are overcome. We frame the core disease control and elimination questions that could be addressed by improved serological tools, discussing challenges and suggesting approaches to increase the feasibility and sustainability of the tool. Conclusions: Accounting for the dynamical context, serosurveys could play a key role in efforts to achieve and sustain elimination.
Asunto(s)
Anticuerpos Antivirales/sangre , Erradicación de la Enfermedad/métodos , Transmisión de Enfermedad Infecciosa/prevención & control , Virus del Sarampión/inmunología , Sarampión/epidemiología , Virus de la Rubéola/inmunología , Rubéola (Sarampión Alemán)/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Simulación por Computador , Monitoreo Epidemiológico , Femenino , Humanos , Lactante , Control de Infecciones/métodos , Masculino , Sarampión/prevención & control , Persona de Mediana Edad , Modelos Estadísticos , Rubéola (Sarampión Alemán)/prevención & control , Estudios Seroepidemiológicos , Adulto JovenRESUMEN
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.