It’s becoming impossible to keep track of the Centers for Disease Control and Prevention’s many different opinions on COVID-19 and masks.

In early 2020, the agency assured the public that masks weren’t necessary and that they wouldn’t work. A few months later, CDC officials changed their minds and decided masks were one of the best ways to slow down the spread of the coronavirus. They started by recommending masks, but eventually urged states to mandate them both outdoors and indoors. But even that changed when the CDC realized that masks were useless outside, and suddenly, they became necessary only indoors.