From COVAX deliveries to vaccination uptake in LMICs: a monthly panel analysis.

BACKGROUND

COVAX was designed to expand COVID-19 vaccine access in low- and lower-middle-income countries (LMICs), but delivered doses did not automatically translate into vaccinations. This study examines whether recent COVAX deliveries were associated with monthly vaccination uptake in LMICs and whether this association varied according to countries' long-run reliance on COVAX.

METHODS

We compiled a monthly panel dataset covering 66 LMICs from April 2021 to October 2022. The outcome was monthly COVID-19 vaccine doses administered per 100 population. The main explanatory variable was a two-month rolling measure of COVAX deliveries per 100 population. We estimated two-way fixed-effects models with country and month fixed effects, controlling for lagged COVID-19 mortality, policy stringency, and economic support. We also conducted robustness, timing, and heterogeneity analyses.

RESULTS

Recent COVAX deliveries were positively associated with vaccination. This relationship remained visible under alternative timing specifications, while placebo‑lead tests did not show comparable patterns. However, the positive delivery-uptake association was weaker in countries with higher long-run reliance on COVAX. These findings suggest that larger recent COVAX deliveries were linked to greater uptake, but that the strength of this relationship varied across country contexts.

CONCLUSIONS

The findings highlight the importance of distinguishing vaccine delivery from vaccine uptake when evaluating global vaccine initiatives. They also suggest that equitable supply mechanisms should be accompanied by stronger support for downstream implementation, delivery readiness, and country-level conditions that help convert delivered doses into vaccinations.