The nation’s health experts on Sunday pleaded with Americans to stay home over the Thanksgiving holiday and forgo any plans to travel or celebrate at large family gatherings, even as airports have recorded a significant rise in passengers.

Dr. Anthony S. Fauci, the country’s top infectious disease specialist, and other health experts relayed a clear message on Sunday morning news shows: with coronavirus cases surging to record levels across the country, turning nearly every state into a hot zone of transmission, the risk of getting infected, whether in transit or in even small indoor gatherings, is high.

Up to 50 million people could be traveling on roads and through airports in the United States over Thanksgiving this year, according to AAA, the biggest travel surge since the pandemic began, despite strong cautions from the Centers for Disease Control and Prevention and other health authorities. A video of a packed airport in Phoenix has been circulating widely on social media. As of Sunday, 47 states — all but Vermont, Maine and Hawaii — were considered high-risk zones for viral transmission, and nationwide hospitalizations were at a record 83,227.