Serological surveillance of SARS-CoV-2: Six-month trends and antibody response in a cohort of public health workers

Ross J. Harris, Heather J. Whitaker, Nick J. Andrews, Felicity Aiano, Zahin Amin-chowdhury, Jessica Flood, Ray Borrow, Ezra Linley, Shazaad Ahmad, Lorraine Stapley, Bassam Hallis, Gayatri Amirthalingam, Katja Höschler, Ben Parker, Alexander Horsley, Timothy J.g. Brooks, Kevin E. Brown, Mary E. Ramsay, Shamez N. Ladhani

Research output: Contribution to journalArticlepeer-review


Background Antibody waning after SARS-CoV-2 infection may result in reduction in long-term immunity following natural infection and vaccination, and is therefore a major public health issue. We undertook prospective serosurveillance in a large cohort of healthy adults from the start of the epidemic in England. Methods Clinical and non-clinical healthcare workers were recruited across three English regions and tested monthly from March to November 2020 for SARS-CoV-2 spike (S) protein and nucleoprotein (N) antibodies using five different immunoassays. In positive individuals, antibody responses and long-term trends were modelled using mixed effects regression. Findings In total, 2246 individuals attended 12,247 visits and 264 were seropositive in ≥ 2 assays. Most seroconversions occurred between March and April 2020. The assays showed > 85% agreement for ever-positivity, although this changed markedly over time. Antibodies were detected earlier with Abbott (N) but declined rapidly thereafter. With the EuroImmun (S) and receptor-binding domain (RBD) assays, responses increased for 4 weeks then fell until week 12–16 before stabilising. For Roche (N), responses increased until 8 weeks, stabilised, then declined, but most remained above the positive threshold. For Roche (S), responses continued to climb over the full 24 weeks, with no sero-reversions. Predicted proportions sero-reverting after 52 weeks were 100% for Abbott, 59% (95% credible interval 50–68%) Euroimmun, 41% (30–52%) RBD, 10% (8–14%) Roche (N) < 2% Roche (S). Interpretation Trends in SARS-CoV-2 antibodies following infection are highly dependent on the assay used. Ongoing serosurveillance using multiple assays is critical for monitoring the course and long-term progression of SARS-CoV-2 antibodies.
Original languageEnglish
Pages (from-to)162-169
Number of pages8
JournalJournal Of Infection
Issue number5
Early online date22 Mar 2021
Publication statusPublished - 1 May 2021


  • Adult
  • Antibodies, Viral
  • Antibody Formation
  • COVID-19
  • England
  • Health Personnel
  • Humans
  • Prospective Studies
  • Public Health
  • SARS-CoV-2


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