Fact check: What percentage of non vaccinated deaths during covid

1. What the major studies actually claim—and why it matters

Large national cohort studies and public-health surveillance reports consistently claim that unvaccinated persons faced far higher risks of hospitalization and death from COVID-19 than vaccinated persons, with the difference greatest in older age groups. U.S. MMWR analyses covering October 2021–December 2022 report mortality rate ratios as high as 14.1 overall and much larger ratios for specific older age bands, indicating that vaccination and boosters—particularly bivalent boosters—provided substantial additional protection against fatal outcomes ^{[1] [4]}. British peer-reviewed work and a Lancet meta-analysis similarly conclude that undervaccination correlated with greater severe outcomes and that thousands of deaths and hospital admissions could have been avoided by higher uptake ^{[3] [2]}. These claims matter because they quantify the direct public‑health impact of vaccine coverage on mortality.

2. How large were the differences in death rates—putting numbers to the statement

Surveillance data from 20–24 U.S. jurisdictions find mortality rate ratios comparing unvaccinated to recently bivalent‑boosted people ranging from 8.4 to 16.3 across variant periods for adults ≥65 and an overall 14.1 estimate for persons ≥12 during part of 2021–2022 ^{[5] [1]}. The same MMWR analyses reported even larger age‑specific ratios—23.7 for ages 65–79 in one dataset—showing the effect size is strongly age‑dependent ^[1]. UK national cohort meta‑analysis and related studies estimated 7,180 avoidable severe outcomes if the population had been fully vaccinated, with the greatest number among those 75 and older, underscoring that even modest absolute differences in high‑risk groups translate into large numbers of deaths prevented ^[2].

3. Why older age and subgroup patterns amplify the message

All cited analyses show a consistent pattern: older adults account for a disproportionate share of COVID-19 deaths, and the protective effect of vaccination is largest where baseline risk is highest. MMWR reports highlight that among adults ≥65, a majority of deaths occurred in ≥80‑year‑olds, and rate ratios remained substantially elevated for unvaccinated persons across variant periods, although the magnitude declined somewhat from BA.5 to XBB.1.5 periods ^{[6] [5]}. UK analyses also found undervaccination was more common in younger, deprived, male and non‑white subgroups, but the largest numbers of avoidable severe outcomes occurred in the oldest cohorts, producing a concentrated prevention opportunity where vaccination coverage lagged ^{[3] [2]}. This concentration clarifies why targeting uptake in older communities yields large mortality reductions.

4. Reconciling different studies and the proportionality hypothesis

Methodological differences—surveillance versus cohort designs, variant periods, booster definitions, and denominators—explain variation in reported rate ratios, but the direction and public‑health implication are uniform: vaccination substantially lowers COVID‑19 mortality. A European actuarial study framed results using a Proportionality Hypothesis, finding COVID‑19 deaths tracked baseline all‑cause mortality patterns and that fully vaccinated groups saw very significantly lower death rates than unvaccinated groups, aligning with national cohort meta‑analyses and MMWR surveillance findings ^{[7] [2]}. The proportionality framing helps interpret why age and baseline vulnerability shape both absolute and relative impacts, and why avoidable deaths concentrate in older cohorts despite differences in percentage estimates across studies.

5. Caveats, limitations and what remains unaddressed

All cited work is observational and uses population surveillance or cohort linkage; confounding by health status, prior infection, behavior, and access to care can influence rate ratios even when studies adjust for known covariates. Time windows tied to variant predominance and booster timing alter estimates: rate ratios fell during later variant periods, reflecting changing immunity landscapes ^[5]. Estimates of “avoidable” outcomes depend on counterfactual assumptions about full uptake and vaccine effectiveness against specific variants ^[2]. Nevertheless, across multiple methods and jurisdictions, the convergent finding is robust: higher vaccination coverage would have prevented a substantial share of COVID‑19 deaths, particularly among the oldest and most vulnerable ^{[3] [1]}.