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Pedersen OB, Nissen J, Dinh KM, Schwinn M, Kaspersen KA, Boldsen JK, Didriksen M, Dowsett J, Sørensen E, Thørner LW, Larsen MAH, Grum-Schwensen B, Sækmose S, Paulsen IW, Frisk NLS, Brodersen T, Vestergaard LS, Rostgaard K, Mølbak K, Skov RL, Erikstrup C, Ullum H, Hjalgrim H. SARS-CoV-2 infection fatality rate among elderly retired Danish blood donors - A cross-sectional study. Clin Infect Dis 2020; 73:e2962-e2969. [PMID: 33103182 PMCID: PMC7665387 DOI: 10.1093/cid/ciaa1627] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 10/21/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Despite 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 older are still scarce. To this end we assessed SARS-CoV-2 seroprevalence among retired blood donors and combined it with national COVID-19 survey data to provide reliable population-based IFR estimates for this age group. METHODS We identified 60,926 retired blood donors age 70 years or older in the rosters of three region-wide Danish blood banks and invited them to fill in a questionnaire on COVID-19 related symptoms and behaviours. Among 24,861 (40.8%) responders, we invited a random sample of 3,200 individuals for blood testing. Overall, 1,201 (37.5%) individuals were tested for SARS-CoV-2 antibodies (Wantai) and compared to 1,110 active blood donors age 17-69 years. Seroprevalence 95% confidence intervals (CI) were adjusted for assay sensitivity and specificity. RESULTS Among retired (age 70 years or older) and active (age 17-69 years) blood donors, adjusted seroprevalences were 1.4% (95% CI: 0.3%-2.5%) and 2.5% (95% CI: 1.3%-3.8%), respectively. Using available population data on COVID-19 related fatalities, IFRs for patients age 70 years or older and for 17-69 years were estimated at 5.4% (95% CI: 2.7%-6.4%) and 0.083% (95% CI: 0.054%-0.18%), respectively. Only 52.4% of SARS-CoV-2 seropositive retired blood donors reported having been sick since the start of the pandemic. CONCLUSION COVID-19 IFR in the age group above 69 years is estimated to be 65 times as high as the IFR for people age 18-69 years.
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Affiliation(s)
- Ole Birger Pedersen
- Department of Clinical Immunology, Zealand University Hospital, Køge, Denmark.,Department of Clinical Medicine, Copenhagen University, Copenhagen
| | - Janna Nissen
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Khoa Manh Dinh
- Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark
| | - Michael Schwinn
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | | | | | - Maria Didriksen
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Joseph Dowsett
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Erik Sørensen
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lise Wegner Thørner
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark
| | | | | | - Susanne Sækmose
- Department of Clinical Immunology, Zealand University Hospital, Køge, Denmark
| | | | | | - Thorsten Brodersen
- Department of Clinical Immunology, Zealand University Hospital, Køge, Denmark
| | | | - Klaus Rostgaard
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Kåre Mølbak
- Infection Disease Preparedness, Statens Serum Institut, Copenhagen, Denmark
| | - Robert Leo Skov
- Infection Disease Preparedness, Statens Serum Institut, Copenhagen, Denmark
| | - Christian Erikstrup
- Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark
| | - Henrik Ullum
- Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Clinical Medicine, Copenhagen University, Copenhagen
| | - Henrik Hjalgrim
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.,Department of Haematology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Clinical Medicine, Copenhagen University, Copenhagen
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