Centers for Disease Control head Robert Redfield said Tuesday that President Donald Trump and Vice President Mike Pence should wear masks to set an example for the public and while both have been consistently tested for the virus.

“Glad to see the president wear a mask this week, and the vice president, and clearly in their situation, they could easily justify that they don’t need to because of all the testing around them and they know they’re not infected,” Redfield said in a live stream with Dr. Howard Bauchner, the editor-in-chief of the journal of the American Medical Association. “But we need them to set the example, as you said, for other individuals.”

Redfield also said that masks could help the federal government get the current outbreak under control. Cases have surged in sunbelt states such as Florida, California, Texas, and Arizona, with some governors shutting down businesses.

“I do think if we could get everybody to wear masks right now — I really do think over the next four, six, eight weeks, we could bring this epidemic until control,” he continued.

A study from Goldman Sachs in late June found that a national mask mandate could save the economy $1 trillion or 5% in GDP. A mask mandate could help the country avoid more lockdowns to prevent the spread of the virus.

Trump made his first debut wearing a mask while on a visit to Walter Reed Military Hospital over the weekend. He has frequently refused to wear a mask during news conferences, rallies and other public events. First lady Melania Trump has also worn a mask — seen in a recent photo on Twitter — claiming it would lead to a “safer and healthier” country in the fall.

The U.S. has the most COVID-19 cases in the world since late March. As of Tuesday, there are nearly 3.4 million infections in the U.S., with the domestic death toll over 136,000, according to data from Johns Hopkins University.