Peer-reviewed article
Drought and child vaccination coverage in 22 countries in sub-Saharan Africa: A retrospective analysis of national survey data from 2011 to 2019
Jason M. Nagata, Adrienne Epstein, Kyle T. Ganson, Tarik Benmarhnia, Sheri D. Weiser ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined whether drought affects childhood vaccination rates in 22 sub-Saharan African countries using data from 137,379 children born between 2011 and 2019. Researchers found that drought at birth was associated with lower rates of BCG, DPT, and polio vaccinations, and drought at 12 months was linked to lower measles vaccination rates. The effects were small but consistent, with stronger associations when drought timing aligned closely with vaccination schedules. The findings suggest that climate shocks can disrupt critical immunisation programmes.
Key points
- Drought at date of birth was negatively associated with BCG vaccination (risk difference -1.5%), DPT vaccination (-1.4%), and polio vaccination (-1.3%)
- Drought at 12 months of age was negatively associated with measles vaccination (risk difference -1.9%)
- A dose-response relationship was found between drought and DPT and polio vaccinations, with strongest associations closest to drought timing
- Only 57.6% of children 12 months and older received all recommended doses of BCG, DPT, polio, and measles vaccinations
- 11.8% of children in the sample were born during drought conditions
Limitations
The study notes heterogeneity in findings across the 22 countries, which limits generalisability. The analysis cannot establish the causal mechanisms by which drought reduces vaccination coverage or identify country-specific factors that may modify these associations.
Abstract
BACKGROUND: Extreme weather events, including droughts, are expected to increase in parts of sub-Saharan Africa and are associated with a number of poor health outcomes; however, to the best of our knowledge, the link between drought and childhood vaccination remains unknown. The objective of this study was to evaluate the relationship between drought and vaccination coverage. METHODS AND FINDINGS: We investigated the association between drought and vaccination coverage using a retrospective analysis of Demographic and Health Surveys data in 22 sub-Saharan African countries among 137,379 children (50.4% male) born from 2011 to 2019. Drought was defined as an established binary variable of annual rainfall less than or equal to the 15th percentile relative to the 29 previous years, using data from Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data. We evaluated the association between drought at the date of birth and receipt of bacillus Calmette-Guérin (BCG), diphtheria-pertussis-tetanus (DPT), and polio vaccinations, and the association between drought at 12 months of age and receipt of measles vaccination. We specified logistic regression models with survey fixed effects and standard errors clustered at the enumeration area level, adjusting for child-, mother-, and household-level covariates and estimated marginal risk differences (RDs). The prevalence of drought at date of birth in the sample was 11.8%. Vaccination rates for each vaccination ranged from 70.6% (for 3 doses of the polio vaccine) to 86.0% (for BCG vaccination); however, only 57.6% of children 12 months and older received all recommended doses of BCG, DPT, polio, and measles vaccinations. In adjusted models, drought at date of birth was negatively associated with BCG vaccination (marginal RD = -1.5; 95% CI -2.2, -0.9), DPT vaccination (marginal RD = -1.4; 95% CI -2.2, -0.5), and polio vaccination (marginal RD = -1.3; 95% CI -2.3, -0.3). Drought at 12 months was negatively associated with measles vaccination (marginal RD = -1.9; 95% CI -2.8, -0.9). We found a dose-response relationship between drought and DPT and polio vaccinations, with the strongest associations closest to the timing of drought. Limitations include some heterogeneity in findings across countries. CONCLUSIONS: In this study, we observed that drought was associated with lower odds of completion of childhood BCG, DPT, and polio vaccinations. These findings indicate that drought may hinder vaccination coverage, one of the most important interventions to prevent infections among children. This work adds to a growing body of literature suggesting that health programs should consider impacts of severe weather in their programming.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.