The gold standard in science — a randomized, double-blinded controlled trial — is impossible to conduct in a pandemic, so researchers have turned to other analyses, said Andrew Noymer, an associate professor of population health and disease prevention at the University of California at Irvine who was not part of the review. Reviews such as the Lancet report compile data from many smaller reports to synthesize those findings.
Spate of new research supports wearing masks to control coronavirus spread
The Washington Post, June 13, 2020
June 12, 2020