Andersen's email to Fauci appeared in a trove of documents obtained last week after a Freedom of Information Act request. The email in question, mailed on Jan. 31, 2020, pointed to a report in Science magazine regarding the global race to share "full sequences of the virus from patients" in order to understand the roots of the virus and learn how it "fits on the family tree of related viruses found in bats and other species."
Andersen was cited in the article, in which he talked of the difficulties scientists face in attempting to determine natural hosts.
Andersen wrote to Fauci regarding the new virus.
"The unusual features of the virus make up a really small part of the genome (<0.1%) so one has to look really closely at all the sequences to see that some of the features (potentially) look engineered," he wrote.
He wrote that his team was in the early stages of looking critically at the data yet discovered that "the genome is inconsistent with expectations from evolutionary theory. But we have to look at this much more closely and there are still further analyses to be done, so those options could still change."
Andersen did not return to emails from Fox News regarding his email to Fauci, or regarding his Twitter account. A spokeswoman from Twitter announced, "The account was deactivated by the user. No action was taken on Twitter's part."
In May, Andersen was mentioned in a New York Times article about a collection of scientists calling for more data on the roots of the virus. The paper reported that Andersen has been a firm "proponent of the overwhelming likelihood of a natural origin."
Soon after the email to Fauci, Andersen entered a group of scientists that wrote, "We do not believe any type of laboratory-based scenario is plausible," according to the Times.
Andersen, after the email was made public last week, retweeted a post that explained he told Fauci that the team "planned to analyze coronavirus genomes to see if SARS-CoV-2 was naturally evolved or engineered."
"They thought perhaps the latter," Dr. Amy Maxmen, a reporter for Nature, tweeted. "But after looking at the evidence, they changed their minds."
Maxmen pointed out in a later Twitter post that "science is a process" and warned against taking these emails out of context. She wrote that people "who willfully ignore that in this novel pandemic have ulterior motives."