Why did the federal guidance on mask-wearing change so quickly? PolitiFact | A look at the data that led to confusing recommendations. Â Â Pedestrians wearing masks out of concern for the coronavirus walk in the Harvard Square neighborhood of Cambridge, Mass., on Sunday. [ STEVEN SENNE | AP ] To say that federal guidance on mask-wearing has been confusing would be an understatement. Back in 2020, during the earliest days of the coronavirus outbreak in the U.S., mask-wearing was discouraged. Then officials changed this guidance, citing clearer findings that the virus could be transmitted by people who showed no symptoms. The advice to wear masks remained in force for about a year, even for people who were vaccinated. But in mid-May 2021 â amid widespread use of vaccines and falling case counts â federal health officials changed their guidance again.