ABSTRACT
BackgroundThere is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. We analysed the impact of filtering facepiece class 2 (FFP2) vs. surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW). MethodsOur prospective multicentre cohort enrolled patient-facing HCWs from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferred mask type when caring for COVID-19 patients outside of aerosol-generating procedures (AGP). For those performing AGPs, we asked whether they used FFP2 irrespective of the patients COVID-19 status (i.e. universal use). The impact of FFP2 on i) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and ii) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed. ResultsWe enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2 respirators. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users (median follow-up 242 days); seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was non-significantly associated with a decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0{middle dot}8, 95% CI 0{middle dot}6-1{middle dot}0, p=0{middle dot}052) and seroconversion (adjusted odds ratio [aOR] 0{middle dot}7, 95% CI 0{middle dot}5-1{middle dot}0, p=0{middle dot}053); household exposure was the strongest risk factor (aHR for positive swab 10{middle dot}1, p<0{middle dot}001; aOR for seroconversion 5{middle dot}0, p<0{middle dot}001). In subgroup analysis, FFP2 use was clearly protective among those with frequent (>20 patients) COVID-19 exposure (aHR 0{middle dot}7, p<0{middle dot}001; aOR 0{middle dot}6, p=0{middle dot}035). Universal FFP2 use during AGPs showed no protective effect (aHR 1{middle dot}1, p=0{middle dot}7; aOR 0{middle dot}9, p=0{middle dot}53). ConclusionRespirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients. FundingSwiss National Sciences Foundation, Federal Office of Public Health, Cantonal Health Department St.Gallen
ABSTRACT
ObjectivesProtecting healthcare workers (HCW) from Coronavirus Disease-19 (COVID-19) is critical to preserve the functioning of healthcare systems. We therefore assessed seroprevalence and identified risk factors for Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) seropositivity in this population. MethodsBetween June 22nd and August 15th 2020, HCW from institutions in Northern/Eastern Switzerland were screened for SARS-CoV-2 antibodies. We recorded baseline characteristics, non-occupational and occupational risk factors. We used pairwise tests of associations and multivariable logistic regression to identify factors associated with seropositivity. ResultsAmong 4664 HCW from 23 healthcare facilities, 139 (3%) were seropositive. Non-occupational exposures independently associated with seropositivity were contact with a COVID-19-positive household (adjusted OR=54, 95%-CI: 31-97) and stay in a COVID-19 hotspot (aOR=2.2, 95%-CI: 1.1-3.9). Blood group 0 vs. non-0 (aOR=0.4, 95%-CI: 0.3-0.7), active smoking (aOR=0.5, 95%-CI: 0.3-0.9) and living with children <12 years (aOR=0.3, 95%-CI: 0.2-0.6) were associated with decreased risk. Occupational risk factors were close contact to COVID-19 patients (aOR=2.8, 95%-CI: 1.5-5.5), exposure to COVID-19-positive co-workers (aOR=2.0, 95%-CI: 1.2-3.1), poor knowledge of standard hygiene precautions (aOR=2.0, 95%-CI: 1.3-3.2), and frequent visits to the hospital canteen (aOR=1.9, 95%-CI: 1.2-3.1). ConclusionsLiving with COVID-19-positive households showed by far the strongest association with SARS-CoV-2 seropositivity. We identified several potentially modifiable risk factors, which might allow mitigation of the COVID-19 risk among HCW. The lower risk among those living with children, even after correction for multiple confounders, is remarkable and merits further study.
