Fact check: What percentage of COVID-19 deaths were among unvaccinated people in the United States in 2021?

Executive Summary — Short, Clear Answer Up Front

In multiple CDC analyses of 2021 surveillance data, the vast majority of reported COVID-19 deaths were among people who were not fully vaccinated: one 13-jurisdiction report found roughly 91% of deaths were among persons not fully vaccinated during April 4–July 17, 2021 (6,132 of 6,748 deaths) ^[1]. Broader surveillance across 25 jurisdictions through December 25, 2021 showed substantially higher death rates among unvaccinated people compared with fully vaccinated people, with age-standardized death rate ratios often exceeding 15-fold during Delta predominance ^{[2] [3]}. These surveillance reports consistently show unvaccinated people faced dramatically higher risks of death in 2021 even as the share of deaths among vaccinated people rose later due to higher vaccine coverage and waning protection without boosters ^{[2] [4] [5]}.

1. Why the 91% figure matters — a large, clear snapshot from spring–summer 2021

The 91% figure comes from a CDC analysis covering April 4–July 17, 2021 in 13 U.S. jurisdictions that reported vaccination status linked to outcomes; investigators reported 6,132 deaths among persons not fully vaccinated and 616 deaths among fully vaccinated persons, producing the 91% vs. 9% split for that interval ^[1]. This is a direct count-based snapshot reflecting outcomes when vaccine coverage was growing but not yet universal and before booster campaigns, and it shows the immediate, observable concentration of deaths among those who had not completed primary vaccination. The figure is not an intrinsic estimate of vaccine effectiveness; it is a descriptive proportion that depends on vaccination coverage, age distribution, timing, and local epidemic intensity, all of which shaped that period’s outcome counts ^{[1] [4]}.

2. What broader surveillance found — rate ratios that quantify risk, not just counts

Broader CDC surveillance across 25 jurisdictions through December 25, 2021 calculated age-standardized incidence rate ratios comparing death rates in unvaccinated versus fully vaccinated adults and found ratios of roughly 16 to 22 times higher during pre-Delta and Delta-predominant periods, with ratios declining where weeks had sparse data ^[2]. These analyses translate the raw count differences into relative risks that adjust for age and differing denominators and therefore more directly measure how much greater the death risk was for unvaccinated individuals. The takeaway is consistent: whether by counts (91% in spring–summer) or adjusted rate ratios (15–22x in parts of 2021), unvaccinated adults experienced far higher mortality than their fully vaccinated peers during 2021 ^{[2] [3]}.

3. Why the share of deaths among vaccinated people rose later — coverage, aging populations, and waning

Later in 2021 and into 2022, reports noted an increasing share of deaths occurring among vaccinated people, driven by higher overall vaccine coverage, older age of vaccinated populations, and waning immunity without boosters; this produced situations where absolute counts of vaccinated deaths rose even while vaccine protection against death remained strong on a per-person basis ^{[5] [4]}. Surveillance from October–November 2021 showed unvaccinated persons had much higher risks (e.g., 53-fold higher risk of death compared to boosted, fully vaccinated persons in some analyses), demonstrating that vaccination plus boosters retained powerful protection even as the vaccinated share of deaths climbed with time and changing coverage patterns ^[6].

4. Limits of these surveillance snapshots — what the numbers don’t tell you on their own

These CDC surveillance reports are essential but have limitations that affect interpretation: they cover subsets of U.S. jurisdictions, depend on accurate linkage of vaccination and outcome records, and the proportions of deaths by vaccination status vary with vaccination coverage, age structure, variant predominance, and timing of booster uptake ^{[2] [1] [4]}. The 91% share is a descriptive result for April–July 2021 in 13 jurisdictions and is not a universal constant for all of 2021 or all places; rate ratios from larger jurisdictional sets provide adjusted estimates of comparative risk and show the same direction of effect but vary by period and geography ^{[1] [2]}.

5. Bottom line — consistent, multi-angle evidence from 2021 surveillance

Across multiple CDC analyses of 2021 data, unvaccinated people accounted for the large majority of COVID-19 deaths during early–mid 2021 (about 91% in the 13-jurisdiction window) and experienced death rates many times higher than fully vaccinated people across variant periods, with age-standardized rate ratios commonly in the mid-teens to low-twenties in 2021 surveillance ^{[1] [2] [3]}. Later increases in the vaccinated share of deaths reflected changing coverage and waning immunity without boosters, not a failure of vaccines to reduce per-person risk; surveillance continued to show substantially lower death risks for those fully vaccinated and boosted ^{[5] [6]}.