Federal officials are considering whether to require airline passengers to have a negative coronavirus test before boarding domestic flights, according to Transportation Secretary Pete Buttigieg. Proof of a negative test result is already required for passengers boarding international flights bound for the United States, under a policy imposed by the Centers for Disease Control and Prevention last month.

In a program that aired on Sunday night, Mr. Buttigieg told “Axios on HBO” that “there’s an active conversation with the C.D.C. right now” about whether to require a negative test for domestic travel as well. “What I can tell you is, it’s going to be guided by data, by science, by medicine, and by the input of the people who are actually going to have to carry this out,” he said.

Asked about the issue at a White House briefing on Monday, Dr. Rochelle Walensky, the director of the C.D.C., said that providing more coronavirus testing at places like airports could help to curb the spread of the virus by people who are contagious but do not know it, because they lack obvious symptoms. “There’s more gathering that happens in airports, and so, to the extent that we have available tests to be able to do testing, this would be yet another mitigation measure to try and decrease risk,” Dr. Walensky said.

The testing requirement for international travelers was imposed as concern grew about more contagious variants circulating in Britain, South Africa and elsewhere. A study published on Sunday suggested that the variant first found in Britain, B.1.1.7, is already spreading rapidly in the United States. “We should be treating every case as if it’s a variant during this pandemic right now,” Dr. Walensky said at a White House briefing days after the rule took effect.