Beyond disease prevention: rotavirus vaccine rollout and child stunting in Tanzania

Tanzania introduced the rotavirus vaccine in January 2013 to reduce the burden of diarrheal disease, a driver of malnutrition. While the vaccine's effect on diarrheal morbidity and mortality is well established, limited evidence exists on its broader effect on child growth outcomes, particularly stunting which affects about 30% of Tanzanian children under five.

Using data from the 2015/16 Tanzania Demographic and Health Survey (TDHS) with a sample of 8949 children, this study applies a reduced-form Regression Discontinuity Design (RDD) exploiting the vaccine eligibility cutoff (children born ≥ November 2012) and Interrupted Time Series Analysis (ITSA) to estimate both immediate and sustained effects of the vaccine rollout on height-for-age z-score (HAZ).

Mean HAZ was -1.34 among vaccine-eligible children and - 1.65 among ineligible children (difference 0.31 SD, p < .001). The preferred quadratic RDD suggests a 0.44 SD gain in HAZ at the eligibility threshold (0.36 SD with covariates); local linear models indicate 0.22-0.26 SD. ITSA shows an immediate gain of 0.38-0.42 SD and a sustained positive post-rollout trend. Placebo cutoffs and falsification outcomes suggest that the effects are not driven by confounding factors.

The introduction of the rotavirus vaccine in Tanzania is associated with reductions in stunting by improving long-term growth outcomes. These findings suggest that vaccination provides benefits beyond infection prevention, serving as an investment in human capital. Policy should prioritise zero-dose and under-vaccinated children, integrate vaccination with maternal and nutrition services and sustain vaccine financing.