The article then quotes a doctor named David Eisenman as saying, “I think people see a mask and they see an illusion of protection.” Though Eisenman’s quote does not quite support the subheading on the article, I reached out to him to see whether he still stands by his interview.

In short, he does not. “These things come back and haunt you,” Eisenman, a professor-in-residence at UCLA, told me. “Science recommendations have evolved. Now I would say that the evidence is very much in favor of masks as an important protector in the spread of COVID-19.”

Eisenman says the article was widely read. People occasionally tweet at him asking how he can be recommending masks now when he didn’t six months ago. He explains that the science changed, and so did his advice, but according to him, “it doesn’t seem to satisfy anybody.”

The “masks make you sicker” idea underscores how online misinformation is like an ocean liner: Once it’s headed in one direction, it’s difficult to turn around. The advice on masks changed seven months ago, but some people have stuck with what experts were saying in the confusing early days. One doctor’s criticisms of masks—which he now recants—live on in Twitter threads. And as people find new ways to share incorrect information, through posts, photos, and videos, social-media platforms are struggling to catch and remove all the hokum. Before long, the conspiracy theories break free of Facebook and infect reality.

— How a bizarre claim about masks has lived on for months, Olga Khazan in The Atlantic