Vaccination inequities among children 12-23 months in India: An analysis of inter-state differences.

Background: Previous research has shown that socioeconomic and demographic risk factors in children are additive and lead to increasingly negative impacts on vaccination coverage. The goal of this study is to examine if different combinations of four risk factors (infant sex, birth order, maternal education level, and family wealth status) vary by state among children 12-23 months in India and to determine the impact of ≥ 1 risk factor on differences in state vaccination rates. Methods: Using data from the National Family Health Survey (NFHS) conducted in India between 2005 and 2006 (NFHS-3) and 2015-2016 (NFHS-4), full vaccination of children 12-23 months was examined. Full vaccination was defined as receipt of one dose of bacillus Calmette-Guérin (BCG), three doses of diphtheria-pertussis-tetanus vaccine (DPT) vaccine, three doses of oral polio vaccine (OPV), and one dose of measles-containing vaccine (MCV). Associations between full vaccination and the four risk factors were assessed using logistic regression. Data were analyzed by the state of residence. Results: A total of 60.9% of children 12-23 months were fully vaccinated, in NFHS-4, ranging from 33.9% in Arunachal Pradesh to 91.3% in Punjab. In NFHS-4, the odds of full vaccination across all states were 15% lower among infants with 2 risk factors versus 0 or 1 risk factors (OR: 0.85, 95% CI: 0.80-0.91), and 28% lower among infants with 3 or 4 risk factors versus 0 or 1 risk factor (OR: 0.72, 95% CI: 0.67-0.78). Overall, the absolute difference in the full vaccination coverage in those with > 2 vs < 2 risk factors decreased from -13% in NFHS-3 to -5.6% in NFHS-4, with substantial variation across states. Conclusions: Disparities in full vaccination exist among children 12-23 months experiencing > 1 risk factor. Indian states that are more populous or located in the north were more likely to have greater disparities.