Impact of Multiple Risk Factors on Vaccination Inequities: Analysis in Indian Infants Over 2 Decades

INTRODUCTION: Several authors have explored the effect of individual risk factors on vaccination inequity in Indian infants. This study explores the combined impact of >1 risk factor on the probability of full vaccination. METHODS: The proportion of fully vaccinated infants (aged 1-2 years) was calculated from the National Family Health Survey conducted during 1997-1998 (National Family Health Survey-2, n=10,211), 2005-2006 (National Family Health Survey-3, n=9,582), and 2015-2016 (National Family Health Survey-4, n=48,715). Full vaccination was defined as receiving Bacille Calmette‒Guerin (1 dose); diphtheria, pertussis, tetanus (3 doses); oral polio (3 doses); and measles (1 dose) vaccines. The association between full vaccination status and 6 factors (infant sex, birth order, family wealth status, maternal education level, residence type, and religion) was analyzed individually, followed by the combined impact of ≥1 of the first 4, using logistic regression models. RESULTS: The AORs for full vaccination in the 3 surveys, respectively, were 1.09, 1.13, and 1.00 for male versus female infants; 0.68, 0.71, and 0.88 for birth order >1 versus birth order 1; 1.54, 1.96, and 1.20 for greater wealth versus lowest wealth stratum; 2.21, 2.27, and 1.27 for any maternal education versus none; 1.08, 1.10, and 1.08 for Hindu versus other religion; and 1.51, 1.10, and 0.88 for urban versus rural residence. The respective ORs of full vaccination in the 3 surveys by the number of risk factors were as follows: 1.26, 1.54, and 1.27 for 3 risk factors; 2.41, 3.23, and 1.68 for 2 risk factors; 4.42, 6.45, and 2.18 for 1 risk factor; and 7.32, 9.84, and 2.61 for no risk factor. CONCLUSIONS: The presence of multiple risk factors had a cumulative negative impact on infant vaccination in India. Despite an improvement over 2 decades, significant inequities persist. SUPPLEMENT INFORMATION: This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health.