WASHINGTON — Nearly 1.3 million people went through U.S. airports on Sunday, the highest level of air travel in more than nine months, despite fear that travel will lead to more cases of COVID-19.

The Transportation Security Administration said it screened 1,284,599 on Sunday, the highest total since March 15. More than 10 million people have traveled by air since Dec. 18, including six days with at least 1 million people getting screened.

Figures on road trips aren’t available, but AAA predicted that about 85 million Americans would travel during the Christmas holiday season, most of them by car.

Dr. Anthony Fauci, the government’s top expert on infectious disease, said that level of travel could lead to a further increase in COVID-19 cases. Fauci said crowded airports make it difficult to maintain social distance, and holiday gatherings combine people from different households.

“As much as we advise against it, nonetheless, it happens,” he said on CNN. “And that’s one of the reasons why we’re concerned about that being a real risk situation for the spread of infection.”

New cases of COVID-19 have been surging for about two months. There have been more than 330,000 reported deaths from the virus.