Fact-checking Tom Cotton's claims about the coronavirus

Over the weekend, Republican Sen. Tom Cotton came under fire for a series of comments and tweets on the coronavirus. On Fox News Sunday morning, Cotton suggested the virus did not originate in an animal market as the Chinese government has claimed, but perhaps from another source, such as an infectious disease research lab nearby. While acknowledging there's no evidence the disease originated there, Cotton questioned the validity of China's statements, saying "China was lying from the beginning, and they're still lying today."

Cotton's theory is one of many that have been floating around as China and other countries aim to get a handle on the outbreak. Here's what we know about the coronavirus.

After his appearance on Fox News, Cotton took to Twitter to clarify his position. He claimed there are "at least four hypotheses about the origin of the virus," ranging from "the engineered-bio weapon hypothesis" to "natural," which Cotton calls "still the most likely but almost certainly not from the Wuhan food market."

In his interview on Fox, Cotton said his conviction that the virus did not originate in the Wuhan food market was based on a study published in the Lancet medical journal in January 2020.

"Epidemiologists who are widely respected from China who have published a study in the international journal The Lancet have demonstrated that several of the original cases did not have any contact with that food market," Cotton said. "The virus went into that food market before it came out of that food market."

Early January statements from the Wuhan Municipal Health Commission had said most cases were related to the South China Seafood Wholesale Market in Wuhan, based on preliminary studies.

Besides Cotton, The Washington Times, citing an Israeli biological warfare analyst, suggested the virus was developed in a lab, potentially as part of a Chinese bioweapons program. A story claiming China planned to admit the virus came from the lab was also circulating on Facebook but flagged by fact-checkers as false.