key: cord-0688206-houaxlno authors: Murongazvombo, Admire S.; Jones, Rachael S.; Rayment, Michael; Pallett, Scott JC.; Mughal, Nabeela; Azadian, Berge; Donaldson, Hugo; Davies, Gary W.; Moore, Luke SP.; Aiken, Alexander M. title: Association between SARS-CoV-2 exposure and antibody status among healthcare workers in two London hospitals: a cross-sectional study date: 2021-06-22 journal: Infect Prev Pract DOI: 10.1016/j.infpip.2021.100157 sha: bad901cb74be1c5f0056c33d671675f64c1cd083 doc_id: 688206 cord_uid: houaxlno Background Patient-facing (frontline) health-care workers (HCWs) are at high risk of repeated exposure to SARS-CoV-2. Aim We sought to determine the association between levels of frontline exposure and likelihood of SARS-CoV-2 seropositivity amongst HCW. Methods A cross-sectional study was undertaken using purposefully collected data from HCWs at two hospitals in London, United Kingdom (UK) over eight weeks in May-June 2020. Information on sociodemographic, clinical and occupational characteristics was collected using an anonymised questionnaire. Serology was performed using split SARS-CoV-2 IgM/IgG lateral flow immunoassays. Exposure risk was categorised into five pre-defined ordered grades. Multivariable logistic regression was used to examine the association between being frontline and SARS-CoV-2 seropositivity after controlling for other risks of infection. Findings 615 HCWs participated in the study. 250/615 (40.7%) were SARS-CoV-2 IgM and/or IgG positive. After controlling for other exposures, there was non-significant evidence of a modest association between being a frontline HCW (any level) and SARS-CoV-2 seropositivity compared to non-frontline status (OR 1.39, 95% CI 0.84-2.30, p=0.200). There was 15% increase in the odds of SARS-CoV-2 seropositivity for each step along the frontline exposure gradient (OR 1.15, 95% CI 1.00-1.32, p=0.043). Conclusion We found a high SARS-CoV-2 IgM/IgG seropositivity with modest evidence for a dose-response association between increasing levels of frontline exposure risk and seropositivity. Even in well-resourced hospital settings, appropriate use of personal protective equipment, in addition to other transmission-based precautions for inpatient care of SARS-CoV-2 patients could reduce the risk of hospital-acquired SARS-CoV-2 infection among frontline HCW. 66 frontline HCW (working in COVID-19 units) is associated with SARS-CoV-2 infection. [12] 67 Our study at two hospitals in London sought to determine the seroprevalence of SARS-CoV-68 2 in HCWs, and whether being a frontline HCW is associated with a higher risk of SARS- To note, both participating hospitals were able to provide access to both appropriate Table I . (Table I) In an adjusted analysis, there was a non-significant evidence of a modest association 219 between being a frontline HCW and SARS-CoV-2 seropositivity OR 1.39 (95% CI 0.84-2.30) 220 (see Table III ). This model included adjustment for age, sex, ethnicity, profession, history of seroprevalence of 14.5% found in tertiary-level maternity-care HCWs in London and the 252 community in London (13.0%) and England (6.0%) at around the same time. [17, 18] 253 However, the seroprevalence from our study differed markedly from other sero-254 epidemiologic studies among HCWs from countries in mainly the Americas and Europe 255 which were carried out during or just after their first COVID-19 wave peak (April-June 2020). [19-33] These studies showed an estimated overall seroprevalence of 8.7% (95% CI 6.7-257 10.9%) but had varying study designs, serology tests and HCW populations which may also 258 account for the divergent findings. [12] 259 260 The high seroprevalence of SARS-CoV-2 in our study could be explained firstly, by our focus seropositivity. This means we may have over-estimated the seropositivity in the entire HCW 271 population of these hospitals. However, we found no statistically significant difference in 272 HCW seropositivity between the initial 3-week and the final 5-week period, so we believe 273 any degree of over-estimation to be modest. Such a lack of difference may also have been 274 because of seroprevalence gradually rising between these two periods, following the peak of 275 the first COVID-19 wave in the UK. Thirdly, the London catchment area had the highest 276 community SARS-CoV-2 seropositivity, COVID-19 cases, hospital admissions, and deaths in 277 the UK during the study period, therefore it is likely that HCWs in our study had a substantial 278 exposure to both community and healthcare-associated SARS-CoV-2 transmission. 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