Advice from U.S. authorities on the need for face masks has flipped back and forth since Covid-19 took hold in 2020. In May, the Centers for Disease Control and Prevention said immunized Americans could ditch their masks in most settings. It reversed course in July amid a rise in cases caused by the more transmissible delta variant. Now, with the quickly spreading omicron variant causing a surge in infections, the agency is urging wider use of medical-grade masks in the general public. It revised earlier guidelines that had discouraged the use of gold-standard N95 masks in order to reserve them for medical workers.
The CDC’s recommendations on when to mask, last updated in October before the omicron variant emerged, say that people age 2 and older who are not fully vaccinated should mask in indoor public places. Those who are fully vaccinated, the agency says, should mask indoors in public where rates of transmission of the virus are substantial or high. Masking is mandatory on public transportation in the U.S. and in transportation hubs such as airports and train stations. The CDC advised Jan. 14 that “you wear the most protective mask you can that fits well and that you will wear consistently” and said that properly fitted masks of the N95 variety provide the highest level of protection.