Are childhood immunisation rates associated with per capita income? Empirical evidence from 95 countries

Vaccination is a relevant prevention measure as a health strategy as it improves population’s health and well-being. This paper examines the relationship between trends in childhood vaccination coverage and per capita income from 2000 to 2020 and, specifically, the existence of convergence between them. We analyse data from two sources. On the one hand, we use per capita income data according to the World Bank classification (low-, lower-middle, upper-middle and high-income countries). On the other hand, we use data from the World Health Organization to analyse eight vaccines (the first dose of Bacillus Calmette–Guérin (BCG); the first and the third dose of Diphtheria-Tetanus-Pertussis (DTP1 and DTP3); the third dose of Hepatitis B (HEPB3); the first and the second dose of Measles-Containing (MCV1 and MCV2); the third dose of Polio (Pol3); and the Tetanus Toxoid (TT2)). We perform a fixed effects model to obtain the correlation between trends in coverage of the 8 vaccines mentioned and income across 95 countries during the first 20 years of the 21st century. Additionally, we follow the Barro and Sala-i-Martín approach to identify conditioned convergence. The study includes 95 countries and eight vaccines. Our findings show a positive correlation for almost all vaccines (BCG: 0.0014, p=0.0006; DTP1: 0.0012, p=0.0006; DTP3: 0.0002, p=0.0009; HepB3: 0.0037, p=0.0011; MCV1: 0.0022, p=0.0010; MCV2: -0.0062, p=0.0044; Pol3: 0.0001, p=0.0010; TT2: 0.0052, p=0.0009). Looking at conditioned convergence, the positive coefficient of the delayed dependent variable implies conditioned convergence for all vaccines (BCG: -0.1145, p=0.0073; DTP1: -0.1105, p=0.00789; DTP3: -0.1097, p=0.0070; HepB3: -0.1184, p=0.0087; MCV1: -0.1115, p=0.0075; MCV2: -0.1376, p=0.0123; Pol3: -0.1089, p=0.0070; TT2: -0.1158, p=0.0131). Hence, even if countries differ in their socioeconomic characteristics, they converge to different steady state. This paper provides new empirical evidence on both the relationship of immunisation coverage rates and per capita income. Our findings may have significant implications for health policies because socio-economic status indicators have a notable impact on immunisation rates.