Sex-differential mortality after routine vaccinations in urban Guinea-Bissau

In addition to the targeted effects, vaccines may also have non-specific effects (NSEs) on child mortality. The NSEs are often sex-differential. Hence, changes in sex-differences in child mortality by vaccination status is important in assessing the effects of new vaccines.

In 2008, Guinea-Bissau replaced diphtheria-tetanus-pertussis vaccine (DTP) with the DTP-containing pentavalent vaccine (Penta; DTP-H. influenza type B-Hepatitis B) at 6, 10 and 14 weeks and yellow fever vaccine (YF) was to be given with measles vaccine (MV) at 9 months. We investigated possible sex-differential mortality rates following Penta and MV+YF vaccination to children aged 6 weeks to 12 months of age.

After 17,313 vaccination contacts for Penta, mortality was 73% (11-170%) higher in girls than boys. In contrast, after 3028 vaccination contacts for MV+YF mortality was 62% (-19-88%) lower for girls than boys, the sex-differences in mortality according to vaccination type being significantly different (p=0.02). Among predominantly Penta and measles unvaccinated children after 6 weeks of age the mortality did not differ by sex.

Penta was associated with higher female than male mortality; an effect which was counteracted by the subsequent administration of MV+YF. Assessing post-vaccination mortality for boys and girls is necessary to improve the vaccination programme.