Trump's CDC director is perpetuating baseless claims that the coronavirus escaped from a Wuhan lab

• Robert Redfield, who led the CDC under Trump, said he thinks the coronavirus escaped from a Wuhan lab.
• "It's not unusual" for pathogens being studied in a lab to infect workers, he told CNN.
• After a month-long investigation in Wuhan, the WHO concluded a lab leak was "extremely unlikely."

More than a year into the pandemic, the origins of the coronavirus remain a mystery.

That uncertainty leaves a door open for unsubstantiated, and sometimes controversial, theories. The latest figure to perpetuate one of these unlikely ideas: Robert Redfield, who served as head of the Centers for Disease Control and Prevention under Donald Trump.

Redfield told CNN in an interview clip that aired Friday that he believes the virus "escaped" from a laboratory in Wuhan. Other members of the Trump administration also pushed this theory last year.

"It's not unusual for respiratory pathogens that are being worked on in a laboratory to infect the laboratory worker," Redfield told CNN, adding, "that's not implying any intentionality."

The former CDC head, who "spent his life in virology," emphasized, though, that this is simply his opinion.

"Other people don't believe that. That's fine. Science will eventually figure it out," Redfield said, adding, "I'm allowed to have opinions now."

A recent USA Today opinion piece articulated a similar idea, stating that lab leaks in the US aren't terribly uncommon, so a laboratory origin for the pandemic shouldn't be ruled out.

But to date, there's no scientific evidence that the coronavirus leaked from a Chinese lab. Even after a month-long investigation into the virus' origins in Wuhan, the World Health Organization concluded that a lab leak was "extremely unlikely."

Why the lab leak theory doesn't hold water

Conspiracy theories about a Wuhan lab leak often involve the Wuhan Institute of Virology, where some scientists were studying coronaviruses prior to the pandemic. The lab is about 8 miles from a wet market linked to some of Wuhan's earliest cases.

But the international WHO team that spent a month in Wuhan spoke with managers and staff at the institute about their safety protocols. It's one of the highest-level biosafety labs in the world.

"Accidents do happen - we have many examples in many countries in the world of past accidents," Peter Ben Embarek, a WHO scientist specializing in food safety and animal disease, said in a February press conference. But in this case, he said, the Wuhan the institute houses a "state-of-the-art lab," so it is "very unlikely that anything could escape from such a place."

Jonna Mazet, a US epidemiologist who has worked with and trained researchers at the institute, also previously told Insider that she thinks "it's highly unlikely this was a lab accident."

Mazet said she helped the staff develop and implement a "very stringent safety protocol."

In fact, the WHO team found no evidence that samples of the novel coronavirus existed in any Wuhan labs, or any other labs in the world, before the pandemic.

Shi Zhengli, a virologist at the Wuhan institute, told Scientific American in April 2020 that she personally checked the coronavirus samples stored at the lab, and found that none matched the new coronavirus' genome.

"That really took a load off my mind," Shi said. "I had not slept a wink for days."

Evidence suggests the virus jumped from animals to people

Redfield told CNN that he does not believe the novel coronavirus jumped from a bat to a human.

According to the WHO team, it is indeed unlikely the virus hopped directly from bats to people. Rather, the most likely explanation is that the coronavirus came into our population via an intermediary animal host, perhaps a pangolin, rabbit, or ferret. One WHO team member suggested wildlife farms in southern China were the likely origin point.

Bats are common virus hosts: Cross-species hops from bat populations also led to the outbreaks of Ebola, SARS, and the Nipah virus.

One study from February 2020 found that the new coronavirus shares 96% of its genetic code with a coronavirus seen in Chinese bat populations. Another 2020 study revealed an even closer match: a 97.1% similarity to a coronavirus called RmYN02, which was found in bats in China's Yunnan province between May and October 2019.

Spreading 'below the radar' in late 2019

Redfield said the coronavirus' highly infectious nature in humans would make "no biological sense" if it came from an animal.

"I do not believe that this somehow came from a bat to a human, and at that moment in time that the virus came to the human, became one of the most infectious viruses that we know in humanity for human-to-human transmission," he told CNN. Redfield added that it normally takes a while for a virus "to figure out how to become more and more efficient."

So he suggested that the virus could have improved its ability to infect people in a lab where people were working on it: "Most of us in a lab,when we're trying to grow a virus, we're trying to make it grow better," Redfield said.

But according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, it's more likely that the virus became more efficient at invading human hosts while spreading undetected in China in late 2019.

In a Friday White House briefing, Fauci said research indicates the coronavirus was spreading "below the radar screen" in China for several weeks, or perhaps a month or more, before the first cases were reported. That allowed the virus "to be pretty well adapted when first recognized," Fauci added.

Redfield also thinks the coronavirus was circulating months before Chinese authorities reported the first cases to the WHO.

"If I was to guess, this virus started transmitting somewhere in September, October in Wuhan," he told CNN.

Chinese government records show the country's first coronavirus case was documented on November 17, 2019, according to the South China Morning Post. Findings from the WHO investigation, meanwhile, show that more than 90 patients in the Hubei province - where Wuhan is located - were hospitalized with pneumonia or coronavirus-like symptoms in October and November 2019.