Timeliness of childhood vaccinations in 31 low and middle-income countries.

BACKGROUND: This study assessed the extent of delays in childhood vaccinations and examined sociodemographic correlates of delayed and missing vaccinations.
METHODS: Datasets from the 2005-7 Multiple Indicator Cluster Surveys from 31 countries were used. Information on vaccinations was based on vaccination cards. Survival analysis was applied to assess age-specific vaccination rates, and multilevel logistic regression analysis was used to assess factors associated with delayed and missing vaccinations.
RESULTS: The median vaccination coverage across all countries varied from 91% measles-containing vaccine (MCV) to 98% bacille Calmette-Guérin vaccine (BCG). The median fraction of timely administered vaccinations was 65% (range 14.5-97.2%) for BCG, 67% (11.6-89.3%) for the first dose of vaccine against diphtheria, tetanus and pertussis (DTP1), 41% (10.8-82.1%) for DTP3, 68% (29.7-90.3%) for the first dose of polio vaccine (polio1), 38% (10.5-81.0%) for polio3 and 51% (22.3-91.1%) for MCV. The median of the median delays across all countries was 2.1 weeks (IQR 0.9-3.0) for BCG, 2.4 weeks (1.5-3.1) for DTP1; 6.3 weeks (3.3-9.0) for DTP3; 2.0 weeks (1.3-3.1) for polio1, 6.6 weeks (4.3-9.3) for polio3 and 4.1 weeks (2.5-5.8) for MCV. A higher number of children in households and lower socioeconomic status were associated with delayed and missing vaccinations; however, the effects of socioeconomic gradient varied by country.
CONCLUSION: Most countries achieved high up-to-date vaccination coverage. However, there were substantial vaccination delays. Collecting information on the timeliness of vaccination in national surveillance systems will provide a more complete view of vaccination coverage. Missing and delayed vaccinations can be addressed jointly in prevention programmes.