Impact of respirator versus surgical masks on SARS-CoV-2 acquisition in healthcare workers: a prospective multicentre cohort

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) versus surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW). Methods Our prospective multicentre cohort enrolled HCW from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferentially worn mask type when caring for COVID-19 patients outside of aerosol-generating procedures. The impact of FFP2 on (1) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and (2) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed. Results We enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users; 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 decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0.8, 95% CI 0.6–1.0) and seroconversion (adjusted odds ratio [aOR] 0.7, 95% CI 0.5–1.0); household exposure was the strongest risk factor (aHR 10.1, 95% CI 7.5–13.5; aOR 5.0, 95% CI 3.9–6.5). In subgroup analysis, FFP2 use was clearly protective among those with frequent (> 20 patients) COVID-19 exposure (aHR 0.7 for positive swab, 95% CI 0.5–0.8; aOR 0.6 for seroconversion, 95% CI 0.4–1.0). Conclusions Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients.

Sars-Cov-2 exposures of healthcare workers and acquisition of COVID-19

“…Similar to the findings of Belan et al 7 , a prospective cohort study at nine healthcare institutions from Switzerland found household exposure to be the strongest risk factor (adjusted hazard ratio 10.1; 95% CI 7·5−13·5) for both HCW SARS-CoV-2 swab positivity and seroconversion in a multivariate regression analysis. 11 This study also found no significant difference between the use of a filtering facepiece class 2 (FFP2) respirator versus the use of a surgical mask 11 which is consistent with the updated systematic review of observational studies for risk factors for COVID-19 among HCWs mentioned above, albeit recognizing the limitations of observational studies. 4 Other high quality systematic reviews have not found any differences for increased risk of transmission to HCWs for other respiratory viruses when comparing medical/surgical masks versus N95 respirators.…”

“…The identified risks to nurses and nurse’s aides may be related to the amount of close contact, hands-on care provided and is consistent with a recent prospective cohort study which assessed the risk by HCW category. 11 An unexplained finding is the decreased risk of COVID-19 among HCWs in LTCFs with regular COVID-19 patient-facing activities. One might expect an increased risk in this setting but it is possible that the HCWs in the LTCFs were previously immunized or infected during the initial wave of COVID-19.…”

Spread of viruses, which measures are the most apt to control COVID-19?

“…Despite the contradictory data during the pandemic [70] , there are several clinical and theoretical arguments in favor of N95 respirators in contact with infected patients. Studies during the pandemic suggested the superiority in terms of filtration of N95 respirators compared to surgical masks, and in some cases [71] , a lower risk of contamination of health care workers. It is now clear that the presence of fine particles exhaled by infected patients and the risk situations in hospitals [3] are two factors that argue in favor of N95 respirators.…”

Measurement of SARS-CoV-2 in air and on surfaces in Scottish hospitals

“…It is difficult to rely on the randomised clinical trial to evaluate the real-world effectiveness of FFP vs. surgical masks for protecting HCW from infection, as it is impossible to control all confounding factors. Some evidence indicates potential benefits for HCW and patients with use of FFP’s 11 , 12 , but successful infection control will include a bundle of measures, not just RPE. Current guidance on use of respiratory protection for healthcare workers suggests use of FFP3 respirators for working with patients with known or suspected infectious diseases transmitted ‘wholly by the airborne route’ or when carrying out AGPs on patients with an infectious disease spread at least partially by droplet or airborne routes, or as a precautionary measure if the hazard is unknown.…”