Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Since 2001, an aid consortium known as Gavi has accounted for over half of vaccines purchased in the 75 eligible countries with an initial GNI below $1,000 per capita. Regression discontinuity estimates suggest most aid for cheap, existing vaccines like hepatitis B and DPT was inframarginal: for instance, hepatitis B doses sufficient to vaccinate roughly 75% of infants raised vaccination rates by single-digit margins. These results are driven by middle-income countries near the eligibility threshold, and do not preclude larger gains for the poorest countries, global externalities via vaccine markets, or impacts on newer vaccines such as pneumococcal or rotavirus for which income eligibility rules were relaxed.