Relative efficacy of masks and respirators as source control for viral aerosol shedding from people infected with SARS-CoV-2: a controlled human exhaled breath aerosol experimental study - eBioMedicine
▻https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(24)00192-0/fulltext
via MaitrePandai @Panda31808732
petit échantillon (n = 44) mais beaucoup de différences sont significatives :
– n’importe quoi est mieux que rien
– le masque en slip est deux fois meilleurs que le chirurgical (mais là, c’est pas significatif) avec une réduction d’un facteur 10, tout de même
– le N95 fait encore 10 fois mieux ou pas loin (facteur de réduction entre 50 et 100)
▻https://www.thelancet.com/cms/attachment/e87110d7-5aea-4023-92ce-b037d530f1da/gr3.jpg
Fig. 3 Ratio of viral RNA in EBA with to without mask controlling for cough, age, sex, BMI, and SARS-CoV-2 variants. a) Fine aerosol, b) Coarse aerosol, c) Total aerosol. The solid diamonds denote the effect estimates, and the error bars show the 95% confidence interval of each estimate. We estimated the ratio of masked to unmasked EBA viral load by aerosol size using linear mixed effect models for censored responses (R package ‘lmec’, version 1.024), controlling for numbers of coughs during the 30-min sampling period, age, sex, BMI, SARS-CoV-2 variants, and random effects of participants and samples within the participant. In a post-hoc test, the difference between N95 and cloth mask in coarse EBA was confirmed to be statistically significant despite a slight overlap in confidence intervals in the lower panel.
Background
Tight-fitting masks and respirators, in manikin studies, improved aerosol source control compared to loose-fitting masks. Whether this translates to humans is not known.
Methods
We compared efficacy of masks (cloth and surgical) and respirators (KN95 and N95) as source control for SARS-CoV-2 viral load in exhaled breath of volunteers with COVID-19 using a controlled human experimental study. Volunteers (N = 44, 43% female) provided paired unmasked and masked breath samples allowing computation of source-control factors.
Findings
All masks and respirators significantly reduced exhaled viral load, without fit tests or training. A duckbill N95 reduced exhaled viral load by 98% (95% CI: 97%–99%), and significantly outperformed a KN95 (p < 0.001) as well as cloth and surgical masks. Cloth masks outperformed a surgical mask (p = 0.027) and the tested KN95 (p = 0.014).
Interpretation
These results suggest that N95 respirators could be the standard of care in nursing homes and healthcare settings when respiratory viral infections are prevalent in the community and healthcare-associated transmission risk is elevated.