It has been a week since Scott Atlas resigned as President Trump’s coronavirus adviser. But even with vaccines on the way, Trump’s flirtation with Atlas’s theory about herd immunity is apparently hard to kick.

During a news conference at the White House on Tuesday, Trump played up the progress being made on those vaccines. But while doing so, during a rare post-election question-and-answer session with reporters at the end of the event, he slipped into a claim about the level of immunity to the coronavirus.

“You do develop an immunity over time, and I hear we’re close to 15 percent — I’m hearing that,” Trump said. “And that is terrific. That’s a very powerful vaccine, in itself.”

It’s not entirely clear where Trump got his 15 percent figure. The White House didn’t immediately respond to a request for comment.

The United States did just happen to surpass 15 million confirmed cases. But that’s not 15 percent of the population; in fact, it’s less than 5 percent of the 320-plus-million U.S. population.

One potential source for Trump’s claim: The Centers for Disease Control and Prevention in late November estimated that more than 15 percent of the U.S. population had been infected with the virus by the end of September. That was significantly more than the number of documented cases — by a factor of about eight. It’s undoubtedly true that many people who contract the virus never get tested.

But we’ve seen record numbers of infections since then — for weeks. That data is more than two months old at this point. If Trump is talking about those numbers, they are way outdated; if he’s talking about total case numbers, he’s way off the mark.

What’s more, it’s far from proven that coming down with the virus once means you have immunity. The CDC has also said recently that if you are infected, reinfections are “uncommon” — within three months. But it has also said that antibodies wane two months after infection. And we have seen reinfections.

We are also still less than a year into the outbreak. While reinfections are “rare” at this point, according to the CDC, the potential seasonality of the virus and the limited period of study means the issue is still being examined. The World Health Organization also said just last week said that reinfections are increasing and they are still studying the issue. Studies show that similar coronaviruses have recurred frequently in people who have previously been infected.

There’s also a problem with how Trump framed it. If he is indeed talking about the number of people who have been infected — versus getting immunity somehow by other, non-specified means — he’s talking about people who have actually gotten sick and many who have died. More than 280,000 people have perished.

It’s good that the vast majority of people contracting the virus have survived, but Atlas’s vision of herd immunity requires many people to fall ill — and die — before you achieve that. Hailing the number of people who have contracted the virus as “terrific” is certainly a curious comment.

Trump has long sought a quick fix to his coronavirus problem. And he has routinely suggested that testing people only makes him and the White House look bad, because it increases the number of positive cases for people who might not have symptoms (despite the fact that they could serve as carriers for others).

In that light, playing up the number of people who got the virus but might not have tested positive for it would be par-for-the-course for Trump. But embracing some form of herd immunity even with a publicly released vaccine just around the corner is certainly strange — especially when many people still need to be convinced to get the vaccine.