Social media posts cite a February 2020 email in which Dr Anthony Fauci advised against mask use as evidence that face coverings do not prevent the spread of COVID-19. But the email from the top US infectious disease specialist reflected the consensus among health authorities early in the COVID-19 emergency, before it was determined that widespread mask use helps curb transmission of the disease.
"Another email reveals Fauci knew masks did not work to stop or slow the spread of the virus," says a June 2, 2021 Instagram post that features a screenshot of the message.
Fauci wrote in the email that he does "not recommend that you wear a mask," and said that "masks are really for infected people to prevent them from spreading infection" rather than "protecting uninfected people from acquiring infection."
A screenshot of an Instagram post taken on June 3, 2021
Similar claims about the email -- which was part of a trove of previously private correspondence published by US news outlet BuzzFeed -- appeared on Instagram and Facebook as well as in an online article.
Face covering requirements during the pandemic sparked a backlash among those who viewed them as an inconvenience or an impingement on personal freedom, leading to persistent misinformation.
Changing guidance on mask use has been driven by evolving understanding of COVID-19 and the virus that causes it, but has helped undermine some people's confidence in the efficacy of face coverings.
US health authorities initially recommended that masks be used by those who had contracted COVID-19 to help prevent its spread. They then expanded that guidance to urge all people to use them, and now say that those who have been fully vaccinated against the disease do not need them in most circumstances.
Fauci's email reflected the consensus at the time among US health experts, including the Centers for Disease Control and Prevention (CDC) and the surgeon general, America's leading public health spokesman.
That consensus soon changed, and in April 2020 US authorities began recommending that face coverings be used by the general population.
"I want to protect myself and protect others, and also because I want to make it be a symbol for people to see that that's the kind of thing you should be doing," Fauci, the director of the National Institute of Allergy and Infectious Diseases (NIAID), told CNN the following month of why he wears a mask.
"When a scientist stops evaluating and incorporating new information, they are effectively no longer a practicing scientist," Neuman said.
"Dr Fauci's emails and statements show a changing understanding and the gradual shift from the goal of preventing hospital collapse to wider virus control measures," he said.
In a June 2020 interview with business news website TheStreet, Fauci cited concern about a shortage of protective equipment for health care workers as a reason for the previous recommendation against widespread face mask use, saying that "now, we have masks."
"The circumstances have changed," he said.
Fauci also admitted in a July 2020 interview with NPR's "All Things Considered" that the "mixed message in the beginning" on masks was "detrimental in getting the message across."
Dr Jonathan Karn, head of the Department of Molecular Biology and Microbiology at Case Western Reserve University School of Medicine in Cleveland, agreed with Fauci's assessment of American mask guidance.
"The US dropped the ball in terms of the advice about masks," he said. "They weren't aggressive enough about telling people to mask up and mask early."
In May 2021, recommendations on face coverings changed again when the CDC lifted mask-wearing guidance for people who are fully vaccinated against COVID-19.
They can "resume activities without wearing a mask or staying six feet apart, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance," the CDC says.
But the health agency still recommends that unvaccinated people wear masks in many circumstances.
NIAID did not respond to a request for comment on the claims about Fauci's email by the time of publication of this article.