RT Journal Article SR Electronic T1 Serological responses to SARS-CoV-2 following non-hospitalised infection: clinical and ethnodemographic features associated with the magnitude of the antibody response JF BMJ Open Respiratory Research JO BMJ Open Resp Res FD British Thoracic Society SP e000872 DO 10.1136/bmjresp-2020-000872 VO 8 IS 1 A1 Adrian M Shields A1 Sian E Faustini A1 Marisol Perez-Toledo A1 Sian Jossi A1 Joel D Allen A1 Saly Al-Taei A1 Claire Backhouse A1 Lynsey A Dunbar A1 Daniel Ebanks A1 Beena Emmanuel A1 Aduragbemi A Faniyi A1 Mark Garvey A1 Annabel Grinbergs A1 Golaleh McGinnell A1 Joanne O'Neill A1 Yasunori Watanabe A1 Max Crispin A1 David C Wraith A1 Adam F Cunningham A1 Mark T Drayson A1 Alex G Richter YR 2021 UL http://bmjopenrespres.bmj.com/content/8/1/e000872.abstract AB Objective To determine clinical and ethnodemographic correlates of serological responses against the SARS-CoV-2 spike glycoprotein following mild-to-moderate COVID-19.Design A retrospective cohort study of healthcare workers who had self-isolated due to COVID-19.Setting University Hospitals Birmingham NHS Foundation Trust, UK (UHBFT).Participants 956 healthcare workers were recruited by open invitation via UHBFT trust email and social media between 27 April 2020 and the 8 June 2020.Intervention Participants volunteered a venous blood sample that was tested for the presence of anti-SARS-CoV-2 spike glycoprotein antibodies. Results were interpreted in the context of the symptoms of their original illness and ethnodemographic variables.Results Using an assay that simultaneously measures the combined IgG, IgA and IgM response against the spike glycoprotein (IgGAM), the overall seroprevalence within this cohort was 46.2% (n=442/956). The seroprevalence of immunoglobulin isotypes was 36.3%, 18.7% and 8.1% for IgG, IgA and IgM, respectively. IgGAM identified serological responses in 40.6% (n=52/128) of symptomatic individuals who reported a negative SARS-CoV-2 PCR test. Increasing age, non-white ethnicity and obesity were independently associated with greater IgG antibody response against the spike glycoprotein. Self-reported fever and fatigue were associated with greater IgG and IgA responses against the spike glycoprotein. The combination of fever and/or cough and/or anosmia had a positive predictive value of 92.3% for seropositivity in self-isolating individuals a time when Wuhan strain SARS-CoV-2 was predominant.Conclusions and relevance Assays employing combined antibody detection demonstrate enhanced seroepidemiological sensitivity and can detect prior viral exposure even when PCR swabs have been negative. We demonstrate an association between known ethnodemographic risk factors associated with mortality from COVID-19 and the magnitude of serological responses in mild-to-moderate disease.Data are available on reasonable request. The anonymised dataset will be made available on reasonable request. Proposals should be directed to the corresponding author.