Estimation of SARS-CoV-2 infection fatality rate by real-time antibody screening of blood donors

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  • Christian Erikstrup
  • Christoffer Egeberg Hother, University of Copenhagen
  • ,
  • Ole Birger Vestager Pedersen, Zealand University Hospital
  • ,
  • Kåre Mølbak, Statens Serum Institut
  • ,
  • Robert Leo Skov, Statens Serumsinstitut
  • ,
  • Dorte Kinggaard Holm, University of Southern Denmark
  • ,
  • Susanne Gjørup Sækmose, Zealand University Hospital
  • ,
  • Anna Christine Nilsson, University of Southern Denmark
  • ,
  • Patrick Terrence Brooks, University of Copenhagen
  • ,
  • Jens Kjærgaard Boldsen
  • Christina Mikkelsen, University of Copenhagen
  • ,
  • Mikkel Gybel-Brask, University of Copenhagen
  • ,
  • Erik Sørensen, University of Copenhagen
  • ,
  • Khoa Manh Dinh
  • Susan Mikkelsen
  • Bjarne Kuno Møller
  • Thure Haunstrup, Alborg University Hospital
  • ,
  • Lene Harritshøj, University of Copenhagen
  • ,
  • Bitten Aagaard Jensen, Alborg University Hospital
  • ,
  • Henrik Hjalgrim, Statens Serum Institut
  • ,
  • Søren Thue Lillevang, University of Southern Denmark
  • ,
  • Henrik Ullum, University of Copenhagen

BACKGROUND: The pandemic due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has tremendous consequences for our societies. Knowledge of the seroprevalence of SARS-CoV-2 is needed to accurately monitor the spread of the epidemic and to calculate the infection fatality rate (IFR). These measures may help the authorities to make informed decisions and adjust the current societal interventions. The objective was to perform nationwide real-time seroprevalence surveying among blood donors as a tool to estimate previous SARS-CoV-2 infections and the population based IFR.

METHODS: Danish blood donors aged 17-69 years giving blood April 6 to May 3 were tested for SARS-CoV-2 immunoglobulin M and G antibodies using a commercial lateral flow test. Antibody status was compared between geographical areas and an estimate of the IFR was calculated. The seroprevalence was adjusted for assay sensitivity and specificity taking the uncertainties of the test validation into account when reporting the 95% confidence intervals (CI).

RESULTS: The first 20,640 blood donors were tested and a combined adjusted seroprevalence of 1.9% (CI: 0.8-2.3) was calculated. The seroprevalence differed across areas. Using available data on fatalities and population numbers a combined IFR in patients younger than 70 is estimated at 89 per 100,000 (CI: 72-211) infections.

CONCLUSIONS: The IFR was estimated to be slightly lower than previously reported from other countries not using seroprevalence data. The IFR is likely several fold lower than the current estimate. We have initiated real-time nationwide anti-SARS-CoV-2 seroprevalence surveying of blood donations as a tool in monitoring the epidemic.

Original languageEnglish
JournalClinical infectious diseases : an official publication of the Infectious Diseases Society of America
Pages (from-to)249-253
Number of pages5
Publication statusPublished - Jan 2021

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