• Sebastian Leck

FACT CHECK: Did COVID-19 leak from a Chinese lab?

UNFOUNDED based on the evidence currently available.

The rumour that the novel coronavirus came from a Chinese laboratory has circulated online for months. There are two versions of this theory: one, that the virus was manufactured and released from a lab, and two, that it was an accidental leak of a virus that occurs naturally. The first claim is verifiably false, while the second is possible but implausible.

Manufactured virus theory

The idea that the virus was created in a lab, which was promoted by a Republican senator and some publications in the US, has been disproven by genetic research. A team of researchers analyzed the genome sequence of the virus and wrote in Nature Medicine that, based on their findings, “SARS-CoV-2 [the novel coronavirus] is not a laboratory construct or a purposefully manipulated virus.”

According to the study, the genomes of the virus show evidence of natural selection, which means that it has evolved in ways that are unexpected and entirely different from viruses available to laboratories (read the full paper here).

The researchers wrote that it is currently “impossible to prove or disprove” theories about an accidental release from a laboratory, but because COVID-19 is so different from previously studied coronaviruses, “[they] do not believe that any type of laboratory-based scenario is plausible.” They say the virus is more likely to have either evolved while in an animal, such as a bat or pangolin, or after its spread to humans.

The closest match to the human novel coronavirus was found in a bat in Yunnan province in China, with a 96 percent similarity, but the virus may have been harboured by another animal between infecting bats and humans. The origin of the virus is not yet clear; early cases were linked to the Huanan Seafood Wholesale Market in Wuhan, China, but the medical journal Lancet found that the first reported case had no links to the market at all.

Accidental release theory

It remains possible, but unlikely, that COVID-19 was released from a lab in China.

At the start of April, media outlets began speculating that an accidental release was a possible scenario. The British Daily Mail ran a story on April 5 claiming that unnamed British politicians feared it was caused by a leak (their reporting has not been independently verified). On April 7, Sky News Australia broadcast a segment claiming COVID-19 could not have come from bats at a wet market, which is considered to be the virus’s most likely origin.

The anchor, Andrew Bolt, cited a report from the South China University of Technology that claimed bats were never a food source in Wuhan and that the animal was not sold at the market. Instead, he said, the author of the paper theorized that a nearby laboratory “just 300 metres” from the market was responsible. The segment also claimed that another nearby lab, the Wuhan Institute of Virology, “bragged about discovering and identifying ‘a large number of new bat and rodent viruses’ in a job ad posted in 2019.”

He was referring to a report written by a Chinese DNA specialist named Botao Xiao, which had not been peer-reviewed—meaning other scientists had not had a chance to review his claims—and did not include any direct evidence (you can read an archived version here). Xiao suggested that one of the two labs near the wet market, the Wuhan Center for Disease Control and Prevention or the Wuhan Institute of Virology at the Chinese Academy of Sciences, was likely the source of the outbreak. He also included stories from Chinese media about a researcher who had quarantined himself for two weeks after he came into contact with bat blood.

Xiao’s conclusions are mainly conjecture. He withdrew the paper at the end of February, telling the Wall Street Journal in an email that “the speculation about the possible origins in the post was based on published papers and media, and was not supported by direct proofs.”

Both laboratories deny they are the source for COVID-19. Shi Zhengli, a researcher at the Wuhan Center for Disease Control and Prevention, told Scientific American that none of the sequences for the novel coronavirus match the coronavirus samples they’ve collected.

The Wuhan Institute of Virology has also issued a public denial. The job postings Sky News describes were published in late 2019 (here and here in Mandarin) to attract scientists to study Ebola and SARS-related coronaviruses in bats. The timing is suspicious, especially given the Chinese government’s history of withholding information, but it doesn’t necessarily mean anything other than that researchers were studying bats.

It’s impossible to completely rule out the potential of a laboratory accident, as Richard H. Ebright, a biologist at Rutgers University, told the Bulletin of Atomic Scientists. He said that coronaviruses were studied at a moderate biosafety level called BSL-2 in Wuhan. “As a result,” Ebright told the Bulletin, “bat coronaviruses at Wuhan [Center for Disease Control] and Wuhan Institute of Virology routinely were collected and studied at BSL-2, which provides only minimal protections against infection of lab workers.”

However, there is significant disagreement among scientists about the leak theory, and no strong evidence pointing to the laboratories. Until new information emerges, it’s safe to say it is unlikely that COVID-19 came from a lab—and even if it did, it was an accidental leak and not a virus created by researchers.