Sen. Rand Paul (R-Ky.) attended Tuesday’s Senate session without wearing a face mask, declaring that he has immunity from the coronavirus — even though experts remain uncertain as to whether recovered covid-19 patients are actually immune to the disease.

In March, Paul, an ophthalmologist, became the first senator to test positive for the novel coronavirus. Word of Paul’s diagnosis prompted two of his fellow senators, Republicans Mike Lee and Mitt Romney, both of Utah, to self-quarantine at the time because of their contact with him.

Most senators and staff members have been wearing cloth face coverings since the Senate returned to session Monday for the first time since late March. Senate Majority Leader Mitch McConnell (R-Ky.) and other top GOP leaders were wearing face masks as they left Tuesday’s Senate Republican luncheon, although they took them off while addressing reporters.

Asked earlier Tuesday why he was not wearing a mask, Paul cited the fact that he had previously tested positive for the virus.

“I have immunity,” Paul told reporters at the Capitol. “I’ve already had the virus. So I can’t get it again, and I can’t give it to anybody.”

When pressed about reports that a new, more contagious strain of the virus may make people more vulnerable to being reinfected, Paul dismissed the possibility and maintained that he has immunity.

“I can’t get it again, nor can I transmit it,” he said. “So of all the people you’ll meet here, I’m about the only safe person in Washington.”

Despite Paul’s statement, no one knows whether recovered covid-19 patients are immune to a new infection — or, if they are immune, how complete or long-lasting that immunity might be. Some kind of immunity post-infection is the most plausible scenario, but simply being positive might not be enough; people might need a certain threshold of antibodies to be protected.

One of Paul’s GOP colleagues, Sen. Mike Braun (Ind.), was also seen not wearing a mask as he entered the Senate Republican luncheon.

“I wore it coming out on the plane and I will if I’m in a tight spot,” Braun said. “I think the social distancing, the hygiene component — everybody’s doing that — but I think the mask part, you need to use your common sense and use it where it makes sense.”

The Centers for Disease Control and Prevention recommends that people wear a cloth face mask that covers their nose and mouth to slow the spread of the novel coronavirus.

“This is to protect people around you if you are infected but do not have symptoms,” the CDC said in guidance posted on its website.

Joel Achenbach contributed to this report.