Effect of Early Measles Vaccine

In addition to protecting against measles, measles vaccine (MV) may have beneficial non-specific effects. We tested the effect of an additional early MV on mortality and measles antibody levels in a randomised trial of an extra dose of early measles vaccine in Burkina Faso and Guinea-Bissau.

Between 2012-15, we randomised 8309 children aged 4-7 months in two rural health and demographic surveillance sites 1:1 to an extra early MV (Edmonston-Zagreb strain) 4 weeks after the third diphtheria-tetanus-pertussis-hepatitis B-Haemophilus-influenzae-type-b vaccine or no extra MV. All children received routine MV at 9 months.

We assessed mortality through home visits and compared mortality from enrolment to 3 years of age in Cox proportional hazards models, censoring for subsequent non-trial MV. Subgroups of participants had blood samples collected at enrolment, before the 9 months MV and in the second year of life to assess measles antibody level.

We registered 145 deaths (mortality rate: 16/1000 person-years). The mortality was lower than anticipated and did not differ by randomisation group (hazard ratio=1.05 (95%CI: 0.75-1.46)). At enrolment, 4% (16/447) of children in Burkina Faso and 21% (90/422) in Guinea-Bissau had protective measles antibody levels. By 9 months of age, no measles-unvaccinated/unexposed child had protective levels, while 92% (306/333) of early MV recipients had. At final follow-up, 98% (186/189) in the early MV group and 97% (196/202) in the control group had protective levels.

Early MV did not reduce all-cause mortality. Most children were susceptible to measles infection at 4-7 months and responded with high antibody levels to early MV.