A systematic review and meta-analysis of the efficacy of N95 respirators and surgical masks for protection against COVID-19

Former meta-analyses concluded that there was not sufficient evidence to determine the effect of surgical masks and N95 respirators. We collected randomized controlled trials (RCTs) and conducted a systematic review and meta-analysis to evaluate the efficacy of N95 respirators and surgical masks for protection against COVID-19. We retrieved relevant RCTs published between January 2019 and January 2023 by searching the PubMed, EMBASE, and Cochrane CENTRAL. Study quality was evaluated using the Cochrane Risk of Bias tool with the RevMan 5.4 software. Meta-analyses were conducted to calculate pooled estimates using the RevMan 5.4 software. A total of six RCTs were finally included. The findings revealed that wearing a mark made little difference in preventing COVID-19 [odds ratio (OR) = 0.10; 95% confidence interval (CI): 0.01–0.93; P = 0.04]. Subgroup analysis showed that the heterogeneity of data was I(2) = 64% (OR = 0.32; 95% CI: 0.06–1.77; P = 0.19) for surgical mask use and I(2) = 0% (OR = 0.03; 95 %CI: 0.01–0.15; P < 0.01) for N95 respirator use. The heterogeneity of data for medical staff was I(2) = 0% (OR = 0.03; 95 %CI: 0.01–0.12; P < 0.01). Meta-analysis indicated a protective effect of N95 respirators against COVID-19, particularly for medical staff. The use of surgical masks is not associated with a lower risk of COVID-19. However, the subgroup using N95 respirators, particularly medical staff, showed a significant protective. These findings suggest that N95 respirators should be reserved for high-risk medical staff in the absence of sufficient resources during an epidemic. But the number of included studies was small, more studies in future analyses is required to reduce the risk of distribution bias.