For months, American public health officials urged people not to buy masks. That guidance was abruptly reversed in April.
Surgeon General Jerome Adams at one point in February said in a social media post "SERIOUSLY PEOPLE, STOP BUYING MASKS."
"I was saying that then because everything we knew about coronaviruses before that point told us that people were not likely to spread when they were asymptomatic. So, the science at the time suggested that there was not a high degree of asymptomatic spread," Adams said on CBS's "Face the Nation."
Officials were also worried about hoarding of personal protective equipment and a dearth of such equipment in some areas.
"But the primary reason was because that's what the science said. And I want the American people to understand. We follow the science and when we learn more, our recommendations change," Adams said.
"But it's hard when people are continuing to talk about things from three, four months ago. I've said consistently for the past three months, ad nauseum on the Internet and in interviews, wear a face covering."
Critics of mandates to wear masks often point to Adams's proclamation and others like it to argue against having to wear face coverings.
The Centers for Disease Control and Prevention recommended earlier in the COVID-19 pandemic that only sick people and healthcare workers caring for sick people wear masks, explicitly stating no one else needed to wear them.
Since then, many counties and states have mandated wearing masks.
Adams told reporters when the new guidance was issued that earlier recommendations were “based on the best evidence available at the time."
"We've learned more about asymptomatic spread. Up to 50 percent of people who can spread this disease, spread it without having symptoms," Adams said on Sunday.
"And that's why the American people need to know that science is about giving the best recommendations you can and when you learn more, you change those recommendations. Our recommendations have changed."