SARS-CoV-2 antibody kinetics in blood donors with a previously positive SARS-CoV-2 antibody test within a seroprevalence survey

Mette B. Levring*, Dorte K. Holm, Anna C. Nilsson, Joschka M. Bauer, Iben S. Jensen, Jesper R. Davidsen, Line D. Rasmussen, Ulrik Sprogøe, Søren T. Lillevang

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


The persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies is a matter of importance regarding the coronavirus disease 19 (COVID-19) pandemic. To observe antibody dynamics, 105 blood donors, positive for SARS-CoV-2 antibodies by a lateral flow test within a seroprevalence study, were included in this study. Thirty-nine (37%) of 105 the donors were confirmed positive by a total Ig Wantai enzyme-linked immunosorbent assay (ELISA). Three (8%) in this group of 39 reported severe and 26/39 (67%) mild to moderate COVID-19 symptoms. By further ELISA-testing, 33/39 (85%) donors were initially positive for IgG antibodies, 31/39 (79%) for IgA, and 32/39 (82%) for IgM, while 27/39 (69%) were positive for all three isotypes. Persistence of IgG, IgA, and IgM was observed in 73%, 79%, and 32% of donors, respectively, after 6–9 months of observation. For IgM antibodies, the decline in the proportion of positive donors was statistically significant (p = 0.002) during 12 months observation, for IgG only the decline at 3 months was statistically significant (p = 0.042). Four donors exhibited notable increases in antibody levels. In conclusion, persistent SARS-CoV-2 IgA antibodies and IgG antibodies at 6–9 months are present in approximately three of four individuals with previous mild to moderate COVID-19.

Original languageEnglish
JournalJournal of Medical Virology
Issue number4
Pages (from-to)1711-1716
Publication statusPublished - Apr 2022


  • antibody
  • blood donors
  • COVID-19
  • lateral flow test
  • SARS-CoV-2
  • Antibodies, Viral/blood
  • Immunoglobulin A/blood
  • Severity of Illness Index
  • Blood Donors/statistics & numerical data
  • Immunoglobulin G/blood
  • Immunoglobulin M/blood
  • Humans
  • Male
  • Seroepidemiologic Studies
  • COVID-19/blood
  • Young Adult
  • Denmark/epidemiology
  • SARS-CoV-2/immunology
  • Adult
  • Female
  • Reinfection/blood
  • Kinetics


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