The exact origin of SARS-CoV-2, the virus that causes the disease COVID-19, remains unknown. Many scientists think that the virus likely originated in bats and then jumped to humans either directly or indirectly, through contact with an animal. Such zoonotic transfers have happened before with the coronaviruses responsible for SARS and MERS.
A paper published in Science in July 2022 analyzed the available evidence and implicated the wildlife trade and the Huanan Seafood Wholesale Market in Wuhan, China, as the site of the spillover. The earliest COVID-19 cases — even the ones with no known connection to the market — cluster around the market, and animals susceptible to SARS-CoV-2, such as raccoon dogs, are known to have been sold in the market in late 2019. A companion paper analyzing genomic data also argues slightly different versions of the virus spilled over twice — an unlikely occurrence if it had come from a lab.
No intermediate animal, however, has been identified. Lacking proof of an animal-to-human transfer, some scientists say more investigation is needed, and that there could have been an accidental laboratory leak, either of a naturally occurring virus or a lab-enhanced one.
U.S. intelligence agencies remain split on the origin, with four entities plus the National Intelligence Council landing on a natural origin, and the FBI and the Department of Energy, according to news reports, concluding a lab origin is “most likely.” Two others are undecided. There remains no proof for either hypothesis.
There nevertheless is agreement that the coronavirus “was not developed as a biological weapon.”
Many scientists with expertise in coronaviruses consider a lab escape unlikely, and a leak of an engineered virus highly implausible, if not impossible.