As U.S. Cases Rise, White House Covid Czar Says It’s Not a Moment to be ‘Excessively Concerned’

And after the Gridiron Club and Foundation’s annual dinner in Washington on April 2, at least 80 attendees tested positive, Tom DeFrank, a contributing editor for National Journal and president of the Gridiron Club, said in an email on Monday afternoon. The number of new cases reported each day has been declining, he said, adding that reported symptoms remain mild, with several asymptomatic cases.

“Now that we are nine days after the dinner, the connection between a new positive test and our dinner is certainly arguable, particularly for public officials who have had a full week of public events,” Mr. DeFrank said in a statement.

“What it reminds us is the pandemic isn’t over,” Dr. Jha said on “Good Morning America,” referring to the number of cases after the Gridiron dinner, which included some Cabinet members. “We are still going to see cases of this virus spreading. And we have to continue to be vigilant. We have to continue to be careful.”

Neither Mr. Biden nor Ms. Pelosi attended the Gridiron dinner, and Ms. Pelosi said on Monday that she would be leaving isolation on Tuesday after testing negative on Monday.

Elsewhere in the House, Representative Rashida Tlaib, said on Monday she had tested positive. In Connecticut, the lieutenant governor, Susan Bysiewicz, said she tested positive, too.

Dr. Jha also told the “Today” show that the C.D.C. would get the final say on the future of the mask mandate on airplanes and other public transportation — but said that extending the requirement, which currently goes through at least April 18, “is absolutely on the table.”

Dr. Jha replaced Jeffrey D. Zients who left the position to return to his private life, according to the White House. Mr. Zients, an entrepreneur and management consultant, steered the White House response and U.S. vaccination campaign through multiple variants.

Noah Weiland contributed reporting.