Infection fatality rate of COVID-19 in community-dwelling populations with emphasis on the elderly: An overview
Background The infection fatality rate (IFR) of Coronavirus Disease 2019 (COVID-19) varies widely according to age and residence status.
Purpose Estimate the IFR of COVID-19 in community-dwelling elderly populations and other age groups from seroprevalence studies. Study protocol: https://osf.io/47cgb.
Data Sources Seroprevalence studies done in 2020 and identified by any of four existing systematic reviews.
Study Selection SARS-CoV-2 seroprevalence studies with ≥1000 participants aged ≥70 years that presented seroprevalence in elderly people; aimed to generate samples reflecting the general population; and whose location had available data on cumulative COVID-19 deaths in elderly (primary cutoff ≥70 years; ≥65 or ≥60 also eligible).
Data Extraction We extracted the most fully adjusted (if unavailable, unadjusted) seroprevalence estimates and sampling procedure details. We also extracted age- and residence-stratified cumulative COVID-19 deaths (until 1 week after the seroprevalence sampling midpoint) from official reports, and population statistics, to calculate IFRs corrected for unmeasured antibody types. Sample size-weighted IFRs were estimated for countries with multiple estimates. Secondary analyses examined data on younger age strata from the same studies.
Data Synthesis Twenty-three seroprevalence surveys representing 14 countries were included. Across all countries, the median IFR in community-dwelling elderly and elderly overall was 2.4% (range 0.3%-7.2%) and 5.5% (range 0.3%-12.1%). IFR was higher with larger proportions of people >85 years. Younger age strata had low IFR values (median 0.0027%, 0.014%, 0.031%, 0.082%, 0.27%, and 0.59%, at 0–19, 20–29, 30–39, 40–49, 50–59, and 60–69 years).
Limitations Biases in seroprevalence and mortality data.
Conclusions The IFR of COVID-19 in community-dwelling elderly people is lower than previously reported. Very low IFRs were confirmed in the youngest populations.
Competing Interest Statement
The authors have declared no competing interest.
No funding was received specifically for this work. Outside this work, the Meta-Research Innovation Center at Stanford (Stanford University) is supported by a grant from the Laura and John Arnold Foundation. Dr Axfors is supported by postdoctoral grants from the Knut and Alice Wallenberg Foundation, Uppsala University, the Swedish Society of Medicine, the Blanceflor Foundation, and the Sweden-America Foundation. The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
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