Kathrine Agergård Kaspersen

SARS-CoV-2 infection fatality rate among elderly retired Danish blood donors - A cross-sectional study

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

DOI

  • Ole Birger Pedersen, Medical Department, Køge Hospital, Køge, Denmark.
  • ,
  • Janna Nissen, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Khoa Manh Dinh
  • Michael Schwinn, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Kathrine Agergård Kaspersen
  • Jens Kjærgaard Boldsen
  • ,
  • Maria Didriksen, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Joseph Dowsett, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Erik Sørensen, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Lise Wegner Thørner, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Margit Anita Hørup Larsen, Department of Clinical Immunology, Copenhagen University Hospital.
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  • Birgitte Grum-Schwensen, Innovational Counsil, Zealand University Hospital, Region Zealand
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  • Susanne Sækmose, Innovational Counsil, Zealand University Hospital, Region Zealand
  • ,
  • Isabella Worlewenut Paulsen, Innovational Counsil, Zealand University Hospital, Region Zealand
  • ,
  • Nanna Lond Skov Frisk, Innovational Counsil, Zealand University Hospital, Region Zealand
  • ,
  • Thorsten Brodersen, Innovational Counsil, Zealand University Hospital, Region Zealand
  • ,
  • Lasse Skafte Vestergaard, Statens Serum Inst, Statens Serum Institut, Dept Sexually Transmitted Dis
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  • 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
  • Henrik Ullum, Department of Clinical Immunology, Copenhagen University Hospital.
  • ,
  • Henrik Hjalgrim, The Danish Multiple Sclerosis Registry, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark/Danish Multiple Sclerosis Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.

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.

Original languageEnglish
JournalClinical infectious diseases : an official publication of the Infectious Diseases Society of America
ISSN1058-4838
DOIs
Publication statusE-pub ahead of print - 26 Oct 2020

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