Andersen noted that the "unusual features" of the virus made up "a really small part" of its genome.
"We have a good team lined up to look very critically at this, so we should know much more at the end of the weekend," he wrote as part of a chain of emails.
"I should mention that after discussions earlier today, Eddie, Bob, Mike, and myself all find the genome inconsistent with expectations from evolutionary theory," Andersen said. "But we have to look at this much more closely and there are still further analyses to be done, so those opinions could still change."
Andersen and his team subsequently published an article in the peer-reviewed journal Nature Medicine where they wrote that they did not "believe that any type of laboratory-based scenario is plausible."
However, the article noted that more scientific data "could swing the balance of evidence to favor one hypothesis over another."
In an email on February 5, 2020, Fauci advised against wearing masks and said that face masks bought in a store would not be effective at protecting against the virus. He was replying to queries from one Sylvia Burwell, who may be to the same Sylvia Burwell who served as secretary for health and human services from 2014 to 2017.
"Masks are really for infected people to prevent them from spreading infection to people who are not infected rather than protecting uninfected people from acquiring infection," Fauci wrote.
"The typical mask you buy in the drug store is not really effective in keeping out virus, which is small enough to pass through material. It might, however, provide some slight benefit in keep out gross droplets if someone coughs or sneezes on you."
n an email chain released by BuzzFeed News on Tuesday night, the NIH director sent Fauci, director of the National Institute of Allergy and Infectious Diseases, a link to a Mediaite article. This report noted that the Fox News anchor Bret Baier had said "multiple sources" believed COVID-19 could have originated from a Chinese lab.
The April 16 email from Collins had "conspiracy gains momentum" in the subject line. Most of the message was redacted, aside from the link to the Mediaite article. Fauci responded to the email from Collins at 2:45 a.m. on April 17, but his response was also redacted.