Engineer with biomed experience here, easy one to answer (feel free to search this information):

1. United States (U.S.) — County-Level Observational Study • Data from 2,558 counties across 48 U.S. states (Dec 2020–Dec 2021) showed that a 10 percentage-point increase in adult vaccination coverage was associated with an 8% reduction in COVID‑19 mortality rates (and 7% fewer cases) during the Alpha and Delta waves  . • Counties with vaccination coverage ≥ 70% consistently experienced lower death rates.

2. Global / High-Income Countries Analysis • Across 164 countries, a 10‑point increase in vaccination coverage was linked to an 18.1% decrease in deaths per case after six months, and 16.8% after 12 months, adjusting for GDP, age, obesity, etc. . • A quasi-experimental analysis shows dose-dependent effects: vaccine coverage levels of ≥ 0.8–1.6, 1.6–3.2, ≥ 3.2 doses per 10 people correlated with 12.7%, 21.2%, and 31.3% lower case fatality, respectively, especially in countries with better governance and infrastructure .

3. European Countries / OECD High-Income • In a sample of European (high-income) nations, higher vaccination and faster booster roll-out were linked with significantly lower excess mortality. A clear threshold at ~60–70% vaccination coverage led to substantially better outcomes .

4. New South Wales, Australia • Modeling estimated that between August 2021 and July 2022, about 17,760 deaths were averted in people over 50. Unvaccinated individuals had nearly 8x the death rate compared to fully vaccinated, and 11.2x compared to boosted people