Background

Estimates of WHO and UNICEF vaccination coverage may provide little insight into the extent to which vaccinations are administered on time. Yet, lack of adherence to the recommended age to receive a specific vaccination may have detrimental health consequences. For example, delays in receiving vaccination will prolong the risk of lack of protection, often when disease risk is highest, such as during early infancy. We estimated the reported age at vaccination, and vaccine coverage at different ages in children from five sub-Saharan African countries.

Methods

We analyzed data from the latest Demographic and Health Programme databases available for Burkina Faso 2010 (n = 15,044 observations), Ghana 2008 (n = 2992), Kenya 2008–9 (n = 6079), Senegal 2010–11 (n = 12,326), and Tanzania 2010 (n = 8023). We assessed, amongst vaccinees, the exact age when vaccine was administered for the three infant doses of pentavalent vaccine (DTP) and the first dose of measles-containing-vaccine (MCV), as well as the proportion of children immunized with these antigens by a certain age. Vitamin A supplementation (VAS) coverage was evaluated as a potential contact visit for vaccine introduction.

Results

For all DTP doses, the median intervals between recommended and actual ages of receiving vaccination ranged from 12, 17 and 23 days in Kenya, to 22, 33 and 45 days in Senegal. MCV was mostly given during the recommended age of 9 months. In each country, there was a large discrepancy in the median age at DTP vaccination between regions. VAS coverage in young children ranged from 30.3% in Kenya to 78.4% in Senegal, with large variations observed between areas within each study country.

Conclusion

In the context of new vaccine introduction, age of children at vaccination should be monitored to interpret data on vaccine-preventable disease burden, vaccine effectiveness, and vaccine safety, and to adapt targeted interventions and messages.

Abbreviations
DHS, Demographic and Health Surveys; DTP, diphtheria, pertussis, and tetanus; DTwP, diphtheria, tetanus, and whole-cell pertussis; EPI, Expanded Programme on Immunization; hepB, hepatitis B; Hib, Haemophilus influenzae type B; IQR, interquartile range; MCV, measles-containing vaccine; PCV, pneumococcal conjugate vaccine; UNICEF, United Nations Children's Fund; VAS, vitamin A supplementation; WHO, World Health Organization; YFV, yellow fever vaccination