Former Vice President Joe Biden broke with coronavirus guidelines on Thursday and shook hands with an aide who greeted him on the tarmac in Milwaukee, Wisconsin.

Biden arrived in Wisconsin to visit Kenosha, the site of a police-involved shooting Aug. 23 that triggered devastating riots. It was a rare journey for Biden, who has campaigned from his Wilmington, Delaware, home to reinforce “social distancing.”

The former vice president has insisted on strict protocols as part of setting an example for the country on managing the risk of coronavirus. He wears a mask almost constantly; he requires journalists to stay 12 feet away; and his few speeches include circles painted on the floor, within which those attending or covering the event are expected to confine their movements.

On Wedndesday, Biden criticized President Donald Trump, saying that he was not setting a good example:

I think a president has the responsibility to set examples, set the right example for how to get out. Not go out and not wear a mask, and not to have large crowds of people standing next to him and not wearing masks, not being a potential cauldron for significant outbreaks of COVID … And so we’ve worked out a protocol where, how I get in the plane, what kind of plane I get on, how it’s sanitized, where — how I engage people. It’s like when I’m engaging all of you, everywhere I go. It’s always at a safe distance, and everybody’s wearing masks.

Both Biden and the aide, advance staffer Brian McPartlin, wore masks while they shook hands. Biden extended his hand first.

Shortly thereafter, Biden touched his mask — another error, as experts recommend washing hands thoroughly before doing so.

Biden said last week that he had not yet been tested for coronavirus, but the campaign told CNN he would be tested regularly in the future.