An expert group drafted by the World Health Organization to help investigate the origins of the coronavirus pandemic says further research is needed to determine how COVID-19 first began, including a more detailed analysis of the possibility it was a laboratory accident.
That stance marks a sharp reversal of the U.N. health agency’s initial assessment of the pandemic’s origins, when it concluded last year that it was “extremely unlikely” that COVID-19 might have spilled into humans from a lab.
In a report released Thursday, WHO’s expert group said “key pieces of data” are still missing to explain how the pandemic began. The scientists said the group would “remain open to any and all scientific evidence that becomes available in the future to allow for comprehensive testing of all reasonable hypotheses.”
It noted that since lab accidents in the past have triggered some outbreaks, the highly politicized theory could not be discounted.
Former U.S. President Donald Trump speculated repeatedly — without evidence — that COVID-19 was started in a Chinese lab. He also accused WHO of “colluding” with China to cover up the initial outbreak, citing the U.N. health agency’s continued public praise of the country.
WHO’s expert group said WHO chief Tedros Adhanom Ghebreyesus sent two letters to senior Chinese government officials in February requesting information including details about the earliest human cases of COVID-19 in the city of Wuhan. The experts said no studies were provided to WHO that assessed the possibility of COVID-19 being a laboratory leak. They said their understanding of how the coronavirus emerged was limited by factors including that not all research presented by Chinese scientists on the virus has been published.
The scientists said numerous avenues of research were needed, including studies evaluating the role of wild animals, which are thought to be COVID-19′s natural reservoir, and environmental studies in places where the virus might have first spread, like the Huanan seafood market in Wuhan.
Last March, WHO released a report about COVID-19′s origins following a highly choreographed visit by international scientists to China, which concluded that the disease most likely jumped into humans from bats and that there was no evidence to suggest there was a connection to a laboratory.
Yet after considerable criticism, including from some of the scientists on WHO’s team, Tedros acknowledged that it was “ premature ” to rule out a lab leak and said he has asked China to be more transparent in sharing information.
In its new report, WHO said they were given access to data including from unpublished blood samples from more than 40,000 people in Wuhan in 2019, which were tested for COVID-19 antibodies. None were found, suggesting the virus was not spreading widely before it was first identified in late December that year.
WHO’s experts called for numerous studies to be done, including testing wild animals to find which species might host COVID-19. They also said the “cold chain” supply theory should be probed — a scientifically questionable theory that China has advanced, arguing that traces of COVID-19 on frozen packaging was causing outbreaks rather than any domestic source.
To investigate whether COVID-19 might have been the result of a lab accident, WHO’s experts said research should be conducted “with the staff in the laboratories tasked with managing and implementing biosafety and biosecurity,” saying that would provide more information about how viruses related to COVID-19 were managed.
China has previously called the suggestion that COVID-19 began in a laboratory “ baseless ” and countered that the virus might have originated in American facilities, which were also known to be researching coronaviruses in animals. The Chinese government has said it supports the search for the pandemic’s origins, but that other countries should be the focus.
Last August, scientists connected to WHO lamented that the search for the pandemic’s origins had stalled and that the window of opportunity was “closing fast.” They warned that collecting data that was now at least two years old was increasingly difficult.
Numerous public health expert s have called for a global commission to investigate COVID-19′s origins, saying that WHO lacks both the political authority and the independence to determine how the pandemic started.
The Associated Press contributed to this article.