Association between ambient temperature and childhood vaccination coverage in low- and middle-income countries

Climate change aggravates infectious diseases and their transmission, with the large impact on children in low- and middle-income countries (LMICs). Vaccination is an essential tool to prevent infectious disease outbreaks; however, the influence of climatic factors on pediatric vaccination rates globally is unclear.

Vaccination data were collected for 609,202 children under 5 years from 50 LMICs using Demographic and Health Surveys (DHS) between 2010 and 2019. Annual temperature exposures after children's birth were assessed with a global meteorological reanalysis product. We applied a multivariable mixed-effects logistic regression model to quantitatively assess the association of annual mean temperature with basic vaccination coverage (complete vaccination with BCG, three doses of DPT-containing vaccine, three doses of polio vaccine, and one dose of measles-containing vaccine), adjusting for individual, maternal, and household-level factors.

Among the analyzed 609,202 children, only 59.56% completed basic immunization, with individual annual temperature exposure above 20 °C. Each 1 °C increase in annual mean temperature was associated with a 2.04% (95% CI, 1.96%-2.08%) decrease in the basic vaccination rate. Temperature increases were associated with larger declines in basic vaccination rates for children in the Middle East and North Africa, and Sub-Saharan Africa. The effects of high temperature on vaccination were significantly greater among later-born children (2.48%; 95% CI, 2.38%-2.57%), those living with less educated mothers (2.36%; 95% CI, 2.27%-2.45%), in less wealthy households (2.53%; 95% CI, 2.43%-2.63%), and in rural areas (2.17%; 95% CI, 2.09%-2.25%).

Our findings provide novel epidemiological evidence linking higher ambient temperature and lower childhood vaccination rates in 50 LMICs. The results underscore the necessity to integrate climate adaptation strategies into vaccination program and build climate-resilient vaccination systems.