At least 53 people have tested positive for the coronavirus after attending an A-list Washington dinner.

At least 53 people have tested positive for the coronavirus since attending The Gridiron Club and Foundation’s annual dinner last Saturday in Washington, the group’s president confirmed on Friday.

The Gridiron Club dinner, an annual white-tie roast between journalists and presidential administrations, was held at the Renaissance Hotel. But a night of good-natured ribbing has devolved into an outbreak of cases among Washington’s elite, including members of Congress, members of the president’s cabinet and journalists.

About 700 people were at the event, including the 628 guests seated in the ballroom, Gridiron organizers said. Attendees were required to show proof of vaccination but not a negative test result, and face masks were not required during the program.

Among those who have publicly announced being infected with the virus after attending the dinner are Commerce Secretary Gina Raimondo; Attorney General Merrick B. Garland; Valerie Biden Owens, the president’s sister; and Representative Adam B. Schiff of California.

President Biden did not attend the dinner.

The development that cases tied to the Gridiron dinner had surpassed 50 was first reported by The Washington Post.

On Wednesday, cases appeared to be contained to just a couple of the tables, but they have since popped up at additional tables. So far, there are no reports of any symptoms more serious than a sore throat or mild fever, said Tom DeFrank, a contributing editor for National Journal and president of the Gridiron Club.

Members have been coming forward since Sunday to notify the club of positive cases, and the club has been informing anyone who sat next to, across from or in proximity to an infected guest, Mr. DeFrank said. “That is what we have done from the start and continue to do,” he added.

This year’s event was the Gridiron dinner’s return after a two-year, pandemic-related absence. In 2020, the organization canceled the event just days before it was set to take place. That year, Dr. Anthony S. Fauci, the nation’s top infectious disease expert, had accepted an invitation but later declined less than two weeks before the event at the start of the pandemic, Mr. DeFrank said. This year, Dr. Fauci was the first guest to accept the invitation, Mr. DeFrank added. “That gave us some optimism,” Mr. DeFrank said, adding that if Dr. Fauci had declined, “that would have told us something.” Dr. Rochelle P. Walensky, the director of the Centers for Disease Control and Prevention, was also at the dinner.

The number of new reported cases among those who attended the dinner has been decreasing since at least Wednesday, Mr. DeFrank said.

“We are hopeful that the downward trend will continue,” he said.