Stine Byberg, Peter Aaby, Amabelia Rodrigues, Christine Stabell Benn, Ane Baerent Fisker
introduction Measles vaccine (MV) can improve health beyond protecting against measles. To avoid wastage of multidose vials, children in Guinea-Bissau are only vaccinated against measles when they are 9 to 11 months old and when six or more children are present. We evaluated the health effects of providing MV to all unvaccinated measles infants aged 9 to 35 months.
Methods We randomized 182 clusters of villages under demographic surveillance in rural Guinea-Bissau in an “ MV-for-all-policy ” arm where we offered MV regardless of the age and number of children present during our visits. biannuals in the villages, or a ‘Restrictive Policy Arm-MV where we followed the national policy. Unvaccinated measles children aged 9 to 35 months were eligible for enrollment and followed up to age 5. In intention-to-treat analyzes, we compared mortality using Cox regression analyzes with age as the underlying timescale. The primary analysis was for children aged 12 to 35 months when assessing eligibility. Interactions with several contextual factors were explored.
Results Between 2011 and 2016, we followed 2778 children in the primary analysis. MV coverage at age 3 was 97% among children eligible for enrollment under the MV-for-all-policy and 48% under the restrictive MV policy. Mortality was 59% lower than expected and did not differ by trial arm (MV-for-all-policy: 45/1405: Restrictive-MV-policy: 44/1373; HR: 0.95 (95% CI 0.64 to 1.43)). The effect of MV for all changed over time: the HR was 0.53 (95% CI 0.27 to 1.07) in the first 1½ years of enrollment, but 1.07. 47 (95% CI 0.87 to 2.50) later (p = 0.02, interaction test). Exploratory analyzes have indicated that the temporal change may be related to interactions with other childhood interventions.
Conclusion The MV-for-all policy increased MV coverage but had no overall effect on overall mortality.