Former New Jersey governor Chris Christie admitted in a frank statement Thursday that he was “wrong” not to wear a mask at a White House event last month where the novel coronavirus spread among several attendees.

The Republican also urged Americans to wear masks in public and chided elected officials who refuse to wear masks and who downplay the importance of social distancing amid a pandemic that has killed at least 216,000 people in the United States. Notably, Christie is a close ally of President Trump, who has often scorned masks.

“I believed that when I entered the White House grounds, that I had entered a safe zone, due to the testing that I and many others underwent every day,” he said in a statement Thursday. “I was wrong.”

Christie, 58, is among more than a dozen people who have tested positive for the coronavirus after attending an event in the Rose Garden on Sept. 26 to honor Trump’s Supreme Court nominee, Amy Coney Barrett.

Christie, who has a history of asthma and is overweight, both factors that increase the risk for complications in covid-19 patients, checked into a hospital in Morristown, N.J., on Oct. 3. He said he spent seven days isolated in the intensive care unit.

The former governor said he should have worn a mask, as recommended by the Centers for Disease Control and Prevention, to the Rose Garden event and in sessions in late September to help Trump prepare for the first debate with former vice president Joe Biden. Christie was in proximity to Trump in the days before the president announced he had tested positive on Oct. 2.

“I was wrong to not wear a mask at the Amy Coney Barrett announcement and I was wrong not to wear a mask at my multiple debate prep sessions with the President and the rest of the team,” Christie said. “I hope that my experience shows my fellow citizens that you should follow CDC guidelines in public no matter where you are and wear a mask to protect yourself and others.”

Trump and the people around the president have frequently flouted those guidelines, eschewing masks and social distancing on several occasions, including at the Rose Garden event in late September. The president said he felt “really good” just days after being hospitalized at Walter Reed National Military Medical Center. When he returned to the White House several days after he was hospitalized, the president removed his mask even though he was still infected.

After his own infection, Trump has also offered a starkly different message than Christie about how seriously to take the virus.

“Feeling really good! Don’t be afraid of Covid,” Trump said in a tweet earlier this month. “Don’t let it dominate your life.”

Christie received criticism in May when he, like many Republican politicians, urged local officials to reopen the economy quickly, saying, “There are going to be deaths no matter what.” But after his experience with covid-19, Christie’s tone has changed.

“It is something to take very seriously,” Christie said Thursday. “The ramifications are wildly random and potentially deadly. No one should be happy to get the virus and no one should be cavalier about being infected or infecting others.”

Still, the former governor said he believes discussions of the pandemic have been hampered by extreme approaches on both sides of the political aisle. Although he fully backed wearing masks and taking social distancing seriously, Christie said he also believes Americans can handle reopening the economy.

“Every public official, regardless of party or position, should advocate for every American to wear a mask in public, appropriately socially distance and to wash your hands frequently every day,” he said. “At the same time, we should be reopening in every corner of this nation under these guidelines.”