(p. A17) The first large randomized community-level study, published last month in Science, found that while generic surgical masks provided a modest (about 10%) reduction in the risk of infection from Delta, cloth masks didn’t significantly reduce risk. Masks may be even less protective against an extremely contagious variant like Omicron.
For the full commentary, see:
(Note: the online version of the commentary has the date Jan. 24, 2022, and has the same title as the print version.)
The article in Science mentioned above is:
Abaluck, Jason, Laura H. Kwong, Ashley Styczynski, Ashraful Haque, Md. Alamgir Kabir, Ellen Bates-Jefferys, Emily Crawford, Jade Benjamin-Chung, Shabib Raihan, Shadman Rahman, Salim Benhachmi, Neeti Zaman Bintee, Peter J. Winch, Maqsud Hossain, Hasan Mahmud Reza, Abdullah All Jaber, Shawkee Gulshan Momen, Aura Rahman, Faika Laz Banti, Tahrima Saiha Huq, Stephen P. Luby, and Ahmed Mushfiq Mobarak. “Impact of Community Masking on Covid-19: A Cluster-Randomized Trial in Bangladesh.” Science 375, no. 6577 (Jan. 14, 2022). DOI: 10.1126/science.abi9069.