Consistent use of a face mask or respirator in indoor public settings is associated with lower odds of a positive SARS-CoV-2 test result. That’s the main conclusion of the latest analysis on the topic.

Compared with no mask use, a cloth mask cut the odds of testing positive by 56%, a surgical mask by 66% and an N95/KN95 by 83%. Full results are published in Morbidity and Mortality Weekly Report.

 PhD candidate Kristin L. Andrejko and colleagues conducted a test-negative design case-control study that enrolled randomly selected residents of California who underwent SARS-CoV-2 testing between February 18 and December 1, 2021.