RT Journal Article SR Electronic T1 The protective effect of SARS-COV-2 antibodies in Scottish healthcare workers JF ERJ Open Research JO erjor FD European Respiratory Society SP 00080-2021 DO 10.1183/23120541.00080-2021 A1 Hani Abo-Leyah A1 Stephanie Gallant A1 Diane Cassidy A1 Yan Hui Giam A1 Justin Killick A1 Beth Marshall A1 Gordon Hay A1 Caroline Snowdon A1 Eleanor J. Hothersall A1 Thomas Pembridge A1 Rachel Strachan A1 Natalie Gallant A1 Benjamin J. Parcell A1 Jacob George A1 Elizabeth Furrie A1 James D. Chalmers YR 2021 UL http://openres.ersjournals.com/content/early/2021/04/15/23120541.00080-2021.abstract AB Background Healthcare workers (HCW) are believed to be at increased risk of 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 HCW's in Scotland (UK) from May to September 2020. 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 2/12/2020) post antibody testing were recorded to determine if the presence of SARS-CoV-2 antibodies protect against re-infection.Results A total of 2063 health and social care workers were recruited for this study. At enrolment 300 HCW had a positive antibody test (14.5%). 11/231 control sera tested positive (4.8%). HCW therefore had an increased likelihood of a positive test (Odds ratio 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 RT-PCR had positive antibodies. 18.7% had an asymptomatic infection. There were 38 new infections with SARS-CoV-2 in HCW 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 (HR 0.15, 95% CI 0.06 to 0.35, p=0.026).Conclusion HCW 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.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Conflict of interest: Dr. Abo-Leyah has nothing to disclose.Conflict of interest: Stephanie Gallant has nothing to disclose.Conflict of interest: Diane Cassidy has nothing to disclose.Conflict of interest: Ms. Giam has nothing to disclose.Conflict of interest: Mr. Killick has nothing to disclose.Conflict of interest: Beth Marshall has nothing to disclose.Conflict of interest: Mr. Hay has nothing to disclose.Conflict of interest: Dr. Snowdon has nothing to disclose.Conflict of interest: Dr. Snowdon has nothing to disclose.Conflict of interest: Mr. Pembridge has nothing to disclose.Conflict of interest: Ms. Strachan has nothing to disclose.Conflict of interest: Ms. Gallant has nothing to disclose.Conflict of interest: Dr. Parcell has nothing to disclose.Conflict of interest: Dr. Parcell has nothing to disclose.Conflict of interest: Dr. Furrie has nothing to disclose.Conflict of interest: Dr. Chalmers reports grants and personal fees from astrazeneca, grants and personal fees from boehringer ingelheim, personal fees from chiesi, grants and personal fees from glaxosmithkline, grants from gilead sciences, grants and personal fees from insmed, personal fees from novartis, personal fees from zambon, outside the submitted work.