The World Health Organization has reported on a four-week trip by an international team of scientists searching for the origin of the coronavirus. Now the World Health Organization and scientists are evaluating how to move forward.
The report describes the findings of several investigations, including when the virus that causes COVID-19 was first observed in humans and which animals may have harbored it.
It places the outbreak's start in the months preceding mid-December, when the virus may have been spreading undetected. It was possibly introduced to the population by an unknown species acting as an intermediary between bats, which carried an ancestral virus, and people.
Although researchers in China tested tens of thousands of wildlife and livestock samples, the team members point to wild-animal markets as a potential source of future leads. They also conclude that the virus leaked from a laboratory is "extremely unlikely."
The World Health Organization report also includes suggestions for thorough studies, such as tracking the trail of farmers and suppliers trading in animals and animal products at Wuhan markets.
The priority should be to "follow the animals," starting with the Huanan market, Eddie Holmes, a virologist at the University of Sydney in Australia, told Nature. Given the large number of animal species that (the virus) can infect, researchers believe that sampling should be as broad as possible.
Linfa Wang, a virologist at Duke-National University of Singapore Medical School, said in the same Nature report that testing archived blood samples for antibodies at the Wuhan Blood Center is the "obvious low-hanging fruit" for determining when the virus first appeared in humans.
The center collects 200,000 donations every year and keeps them for two years. The report recommends testing blood samples in blood banks across China and around the world, concentrating on the six months before the first reported cases.
Other researchers believe that more data about the first reported cases is required, such as complete genome sequences to show their diversity and what the early virus looked like.
The visit to Wuhan was the first step in a World Health Organization process that began in May 2020 and will be accompanied by longer-term studies, according to an agreement between China and the World Health Organization.
