Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection Fatality Rate among Elderly Danes: A Cross-sectional Study on Retired Blood Donors

Ole Birger Pedersen*, Janna Nissen, Khoa Manh Dinh, Michael Schwinn, Kathrine Agergård Kaspersen, Jens Kjærgaard Boldsen, Maria Didriksen, Joseph Dowsett, Erik Sørensen, Lise Wegner Thørner, Margit Anita Hørup Larsen, Birgitte Grum-Schwensen, Susanne Sækmose, Isabella Worlewenut Paulsen, Nanna Lond Skov Frisk, Thorsten Brodersen, Lasse Skafte Vestergaard, Klaus Rostgaard, Kåre Mølbak, Robert Leo SkovChristian Erikstrup, Henrik Ullum, Henrik Hjalgrim

*Corresponding author for this work

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Abstract

Background: Although the vast majority of individuals succumbing to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are elderly, infection fatality rate (IFR) estimates for the age group ≥70 years are still scarce. To this end, we assessed SARS-CoV-2 seroprevalence among retired blood donors and combined it with national coronavirus disease 2019 (COVID-19) survey data to provide reliable population-based IFR estimates for this age group. Methods: We identified 60â-926 retired blood donors aged ≥70 years in the rosters of 3 regionwide Danish blood banks and invited them to fill in a questionnaire on COVID-19-related symptoms and behaviors. Among 24â-861 (40.8%) responders, we invited a random sample of 3200 individuals for blood testing. Overall, 1201 (37.5%) individuals were tested for SARS-CoV-2 antibodies (Wantai) and compared with 1110 active blood donors aged 17-69 years. Seroprevalence 95% confidence intervals (CIs) were adjusted for assay sensitivity and specificity. Results: Among retired (aged ≥70 years) and active (aged 17-69 years) blood donors, adjusted seroprevalences were 1.4% (95% CI,. 3-2.5%) and 2.5% (95% CI, 1.3-3.8%), respectively. Using available population data on COVID-19-related fatalities, IFRs for patients aged ≥70 years and for 17-69 years were estimated at 5.4% (95% CI, 2.7-6.4%) and. 083% (95% CI,. 054-.18%), respectively. Only 52.4% of SARS-CoV-2-seropositive retired blood donors reported having been sick since the start of the pandemic. Conclusions: COVID-19 IFR in the age group >69 years is estimated to be 65 times the IFR for people aged 18-69 years.

Original languageEnglish
JournalClinical Infectious Diseases
Volume73
Issue number9
Pages (from-to)E2962-E2969
ISSN1058-4838
DOIs
Publication statusPublished - 2021

Bibliographical note

Publisher Copyright:
© 2020 The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America.

Keywords

  • COVID-19
  • epidemiology
  • infection fatality rate
  • SARS-Cov-2 antibody test
  • SARS-CoV-2 seroprevalence

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