ERJ Open Research (Jun 2021)

The protective effect of SARS-CoV-2 antibodies in Scottish healthcare workers

  • Hani Abo-Leyah,
  • Stephanie Gallant,
  • Diane Cassidy,
  • Yan Hui Giam,
  • Justin Killick,
  • Beth Marshall,
  • Gordon Hay,
  • Caroline Snowdon,
  • Eleanor J. Hothersall,
  • Thomas Pembridge,
  • Rachel Strachan,
  • Natalie Gallant,
  • Benjamin J. Parcell,
  • Jacob George,
  • Elizabeth Furrie,
  • James D. Chalmers

DOI
https://doi.org/10.1183/23120541.00080-2021
Journal volume & issue
Vol. 7, no. 2

Abstract

Read online

Background Healthcare workers (HCWs) are believed to be at increased risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It is not known to what extent the natural production of antibodies to SARS-CoV-2 is protective against re-infection. Methods A prospective observational study of HCWs in Scotland (UK) from May to September 2020 was performed. The Siemens SARS-CoV-2 total antibody assay was used to establish seroprevalence in this cohort. Controls, matched for age and sex to the general local population, were studied for comparison. New infections (up to 2 December 2020) post antibody testing were recorded to determine whether the presence of SARS-CoV-2 antibodies protects against re-infection. Results A total of 2063 health and social care workers were recruited for this study. At enrolment, 300 HCWs had a positive antibody test (14.5%). 11 out of 231 control sera tested positive (4.8%). HCWs therefore had an increased likelihood of a positive test (OR 3.4, 95% CI 1.85–6.16; p<0.0001). Dentists were most likely to test positive. 97.3% of patients who had previously tested positive for SARS-CoV-2 by reverse transcriptase (RT)-PCR had positive antibodies. 18.7% had an asymptomatic infection. There were 38 new infections with SARS-CoV-2 in HCWs who were previously antibody negative, and one symptomatic RT-PCR-positive re-infection. The presence of antibodies was therefore associated with an 85% reduced risk of re-infection with SARS-CoV-2 (hazard ratio 0.15, 95% CI 0.06–0.35; p=0.026). Conclusion HCWs were three times more likely to test positive for SARS-CoV-2 than the general population. Almost all infected individuals developed an antibody response, which was 85% effective in protecting against re-infection with SARS-CoV-2.