The initial attempt by the World Health Organization to discover the origins of the pandemic virus in 2020 and 2021 — a joint mission with China — ran aground on uncertainty. This prompted the WHO director general, Tedros Adhanom Ghebreyesus, to create a new scientific advisory group to keep looking, along with setting up a framework for catching novel pathogens when they emerge. The new group has issued its first report, which points to a continuing roadblock: China. If the origin of a pandemic that has killed more than 6 million people is ever to be discovered, China must be more open to investigation.
Two broad hypotheses have arisen about how the virus first infected humans in Wuhan in late 2019. One is zoonotic spillover, a leap from animal to human, perhaps through an intermediate host. This pathway has precedent in other epidemics and throughout history, but the animal host or source remains a mystery. The second hypothesis is that the infection might have resulted from a laboratory accident or an inadvertent spill connected to the Wuhan Institute of Virology (WIV) or another lab. At the time, the WIV was carrying out experiments using genetically modified viruses similar to the pandemic strain, although no direct evidence of such a leak has surfaced.
The new panel, the Scientific Advisory Group for the Origins of Novel Pathogens, or SAGO, says that “at the present time” the epidemiological and genetic sequencing data indicate the ancestral strains to the pandemic virus had a zoonotic origin, noting similarity to bat coronavirus samples from elsewhere in China and Laos. However, the panel cautioned, “so far neither the virus progenitors nor the natural/intermediate hosts or spillover event to humans have been identified.” While earlier studies pointed to the Huanan seafood market in Wuhan as playing an important role in the spread of the virus, the panel believes further studies are needed. The panel also says that while “there has not been any new data made available to evaluate the laboratory as a pathway” for the outbreak, “further investigations” are needed “into this and all other possible pathways.” The panel calls out the need to study the trade of wild and domestic animals in Wuhan and Hubei province, some of which were sold in Wuhan markets.
The report suggests a large number of avenues for further inquiry. For example, the records of some 76,000 patients who went to 233 health institutions in Wuhan in the months before the outbreak were previously examined by China. The first WHO-China investigation was told none of these cases were the pandemic virus. However, the criteria were extremely narrow — so many asymptomatic cases might have been missed.
It is now known that China’s leaders covered up the outbreak in the first weeks of 2020, when the pandemic exploded. They have also rejected calls for more investigation, and rejected the lab leak hypothesis, while insisting the virus might have come from abroad. The SAGO report does not provide conclusive answers. But much of the research it calls for must be carried out in China, and will require China to be more open than it has been so far.