It is the world’s most pressing scientific puzzle, but experts warn there may never be conclusive answers over the source of the coronavirus, after an investigative effort marked from the start by disarray, Chinese secrecy and international rancour.
January 11 marks the anniversary of China confirming its first death from COVID-19, a 61-year-old man who was a regular at the now-notorious Wuhan wet market.
Nearly two million deaths later, the pandemic is out of control across much of the world, leaving tens of millions ill, a pulverised global economy and recriminations flying between nations.
Yet China, which has broadly controlled the pandemic on its soil, is still frustrating independent attempts to trace the virus’ origins and the central question of how it jumped from animals to humans.
There is little dispute that the virus which brought the world to its knees sparked its first known outbreak in late 2019 at a wet market in the central Chinese city of Wuhan where wildlife was sold as food, and the pathogen is believed to have originated in an undetermined bat species.
But the trail ends there, clouded by a mishmash of subsequent clues that suggest its origins may predate Wuhan as well as theories — amplified by US President Donald Trump — that it leaked from a Wuhan lab.
Establishing the source is vital for extinguishing future outbreaks early, leading virologists say, providing clues that can guide policy decisions on whether to cull animal populations, quarantine affected persons, or limit wildlife hunting and other human-animal interactions.
“If we can identify why they (viruses) keep emerging, we can reduce those underlying drivers,” said Peter Daszak, president of EcoHealth Alliance, a global NGO focused on infectious disease prevention.
China won early kudos for reporting the virus and releasing its gene sequence in a timely manner, compared with its cover-up of the 2002-03 SARS outbreak.
But there has also been secrecy and shifting stories.
Wuhan authorities initially tried to cover up the outbreak and later spent precious weeks denying human-to-human transmission.
Early on, Chinese officials declared flatly that the outbreak began at the Huanan Seafood Market in Wuhan.
But Chinese data in January 2020 showed that several of the first cases had no known links to the now-shuttered market, suggesting a source elsewhere.
China’s story morphed again last March when top Chinese disease control official Gao Fu said the market was not the source, but a “victim”, a place where the pathogen was merely amplified.
But China has since failed to publicly connect any dots, releasing scant information on animal and environmental samples taken at the market that could aid investigators, experts say.
And it has kept foreign experts at arm’s length. A planned mission by World Health Organization virus sleuths was in limbo after China denied them entry.
After a rare rebuke from the head of the WHO, China announced on Monday the 10-strong team would be allowed in this week.