ABSTRACT
ABSTRACT Background There 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). Methods Our 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 patient’s 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. Results We enrolled 3’259 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] 0·8, 95% CI 0·6-1·0, p=0·052) and seroconversion (adjusted odds ratio [aOR] 0·7, 95% CI 0·5-1·0, p=0·053); household exposure was the strongest risk factor (aHR for positive swab 10·1, p<0·001; aOR for seroconversion 5·0, p<0·001). In subgroup analysis, FFP2 use was clearly protective among those with frequent (>20 patients) COVID-19 exposure (aHR 0·7, p<0·001; aOR 0·6, p=0·035). Universal FFP2 use during AGPs showed no protective effect (aHR 1·1, p=0·7; aOR 0·9, p=0·53). Conclusion Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients. Funding Swiss National Sciences Foundation, Federal Office of Public Health, Cantonal Health Department St.Gallen