COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Primary Prevention Iannone P, Castellini G, Coclite D, et al. The need of health policy perspective to protect Healthcare Workers during COVID-19 pandemic. A GRADE rapid review on the N95 respirators effectiveness. PLoS One. 2020 Jun 3;15(6):e0234025. doi: 10.1371/journal.pone.0234025. eCollection 2020.

Protecting Health Care Workers (HCWs) during routine care of suspected or confirmed COVID-19 patients is of paramount importance to halt the SARS-CoV-2 (Severe Acute Respiratory Syndrome-Coronavirus-2) pandemic. The WHO, ECDC and CDC have issued conflicting guidelines on the use of respiratory filters (N95) by HCWs. We searched PubMed, Embase and The Cochrane Library from the inception to March 21, 2020 to identify randomized controlled trials (RCTs) comparing N95 respirators versus surgical masks for prevention of COVID-19 or any other respiratory infection among HCWs. The grading of recommendations, assessment, development, and evaluation (GRADE) was used to evaluate the quality of evidence. Four RCTs involving 8736 HCWs were included. We did not find any trial specifically on prevention of COVID-19. However, wearing N95 respirators can prevent 73 more (95% CI 46-91) clinical respiratory infections per 1000 HCWs compared to surgical masks (2 RCTs; 2594 patients; low quality of evidence). A protective effect of N95 respirators in laboratory-confirmed bacterial colonization (RR = 0.41; 95%CI 0.28-0.61) was also found. A trend in favour of N95 respirators was observed in preventing laboratory-confirmed respiratory viral infections, laboratory-confirmed respiratory infection, and influenza like illness. We found no direct high quality evidence on whether N95 respirators are better than surgical masks for HCWs protection from SARS-CoV-2. However, low quality evidence suggests that N95 respirators protect HCWs from clinical respiratory infections. This finding should be contemplated to decide the best strategy to support the resilience of healthcare systems facing the potentially catastrophic SARS-CoV-2 pandemic.

Discipline / Specialty Area Score
Infectious Disease
Emergency Medicine
General Internal Medicine-Primary Care(US)
Intensivist/Critical Care
Occupational and Environmental Health
Public Health
Family Medicine (FM)/General Practice (GP)
Comments from MORE raters

Emergency Medicine rater

I work in the Emergency Department and as a front-line worker, I think this is an important study.

Family Medicine (FM)/General Practice (GP) rater

The abstract soft-pedals the strong statement in the conclusion.

Occupational and Environmental Health rater

In my impression in clinical practice, protection using an N95 respirator is effective in COVID-19 infection.

Respirology/Pulmonology rater

This is a retrospective meta analysis of poor data results in findings that are questionable. However, in the front-line clinical environment, supplies of N95 and data are limited, and most practitioners are responding to internal and external fear by attempting to use N95 masks as much as possible, regardless of the data. The need for policy remains important.

Respirology/Pulmonology rater

As a pulmonary and critical care physician, I find this topic relevant and the analysis intriguing. Just hard to compare these studies and outcomes in this analysis which seems to read more like a review.