Sen. Tom Cotton (R-Ark.) repeated a fringe theory suggesting that the ongoing spread of a coronavirus is connected to research in the disease-ravaged epicenter of Wuhan, China.

Cotton referenced a laboratory in the city, the Wuhan National Biosafety Laboratory, in an interview on Fox News’s “Sunday Morning Futures.” He said the lab was near a market some scientists initially thought was a starting point for the virus’s spread.

“We don’t know where it originated, and we have to get to the bottom of that,” Cotton said. “We also know that just a few miles away from that food market is China’s only biosafety level 4 super laboratory that researches human infectious diseases.”

Yet Cotton acknowledged there is no evidence that the disease originated at the lab. Instead, he suggested it’s necessary to ask Chinese authorities about the possibility, fanning the embers of a conspiracy theory that has been repeatedly debunked by experts.

“Now, we don’t have evidence that this disease originated there, but because of China’s duplicity and dishonesty from the beginning, we need to at least ask the question to see what the evidence says,” Cotton said. “And China right now is not giving any evidence on that question at all.”

Cotton is referring to a well-known lab in Wuhan, a “Cellular Level Biosafety Level 4” facility with a high level of operational security that works on researching dangerous pathogens.

In response to Cotton’s remarks, as well as in previous interviews with The Washington Post, numerous experts dismissed the possibility the coronavirus may be man-made.

“There’s absolutely nothing in the genome sequence of this virus that indicates the virus was engineered,” said Richard Ebright, a professor of chemical biology at Rutgers University. “The possibility this was a deliberately released bioweapon can be firmly excluded.”

Vipin Narang, an associate professor at the Massachusetts Institute of Technology, said it is “highly unlikely” the general population was exposed to a virus through an accident at a lab.

“We don’t have any evidence for that,” said Narang, a political science professor with a background in chemical engineering.

“It’s a skip in logic to say it’s a bioweapon that the Chinese developed and intentionally deployed, or even unintentionally deployed,” Narang said.

After the story published, Cotton as part of a series of tweets made a distinction between the possibility the coronavirus is a man-made result of biological weapons research – which experts say should be dismissed – and other possibilities such as a lab accident. He also continued to list the engineered virus as a “hypothesis.”

Ebright, in a tweet to Cotton, said he was “pleased to hear you now distinguish” between those ideas.

The British publication the Daily Mail was one of the first to suggest a connection between the coronavirus and the laboratory in Wuhan. Later, the Washington Times ran a story under the headline, “Coronavirus may have originated in lab linked to China’s biowarfare program.”

Cotton’s Sunday remarks were not the first time he has suggested the virus may have originated in the Wuhan lab. Chinese Ambassador to the United States Cui Tiankai pushed back on such suggestions in an interview with CBS’s “Face the Nation” earlier this month.

“It’s true that a lot is still unknown,” Cui said when CBS host Margaret Brennan asked about Cotton’s claims. “But it’s very harmful, it’s very dangerous, to stir up suspicion, rumors and spread them among the people. For one thing, this will create panic. Another thing is that it will fan up racial discrimination, xenophobia, all these things that will really harm our joint efforts to combat the virus.”

Cotton responded to the ambassador in a pair of tweets following the interview, referencing the Wuhan lab. “Where did it start? We don’t know. But burden of proof is on you & fellow communists,” he wrote.

After Cotton’s Sunday remarks, Narang said, “These kinds of conspiracy theories are unhelpful.”

“I don’t think it’s particularly helpful, and it’s borderline irresponsible to — and it’s without evidence, so at this point it’s a conspiracy theory — peddle it,” he said. “Cotton should spend more time funding the agencies in the United States that can help contain and combat the virus rather than trying to assign blame.”

Adam Taylor contributed to this report.

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