The blame game between China and the United States on the origin of the coronavirus pandemic has fuelled a host of theories, some more believable than others.
At the start of the outbreak in December, the most mainstream assumption was that the virus originated from a so-called wet market in Wuhan, the Chinese city where the first COVID-19 cases were reported.
But as the virus spread globally, the role of public-health laboratories in Wuhan came under increasing scrutiny.
In two labs in Wuhan, long-running experiments with bat viruses helped scientists quickly identify the coronavirus as most likely to have come from the nocturnal mammal, but those same labs have also fuelled biosafety concerns.
The practice of collecting viruses from bats first burst into public view in the early weeks of the outbreak when Shi Zhengli, a noted scientist with the Wuhan Institute of Virology, refuted a swirl of online accusations both at home and abroad that the coronavirus may have leaked from her institute, where a lab certified as BSL-4, the highest level for handling dangerous pathogens, opened three years ago.
Director-Generalof the World Health Organization Tedros Adhanom Ghebreyesu has called such speculation part of an “infodemic” of fake news surrounding the coronavirus, while other public health officials said they belong with the slew of conspiracy theories claiming that the virus was engineered (all scientists who have studied the genome of the virus agree that would be impossible).
But some scientists, both within China and elsewhere, say an accidental leak remains a possibility – insofar as there is no evidence to disprove it.
“There is nothing ‘fake’ about lab accidents,” said Richard Ebright, a molecular biologist and director at the Waksman Institute of Microbiology at Rutgers University in New Jersey, US. “There also is nothing ‘conspiratorial’ about lab accidents.”
In China, research on bat viruses began in earnest shortly after the SARS epidemic subsided.
The 2003 outbreak, which originated in the southern province of Guangdong, proved particularly deadly in parts of Asia. Of the more than 8,000 people infected, 84 percent of the fatal cases were in China. The virus was later traced to a palm civet that had been infected by a bat.
Bats are most prevalent in the caves in Yunnan province in China’s southwestern borderland.
So, over the past 10 years, Shi and other Wuhan virologists have made numerous expeditions to collect viruses from different bat species, building up Asia’s largest virus bank, according to the institute’s newsletter.
“Through their work on bats, they’ve found a huge diversity of SARS-like virus in bats and flagged some of these viruses that may have an impact on human health,” said Leo Poon, a virologist at the University of Hong Kong who co-authored a paper with Shi in 2010.
Poon said once the genome of the coronavirus was sequenced in early January, Shi was able to confirm its likely source as a bat by retrieving a bat virus sample from her store that was 96 percent similar.