It means we’ve environmental sampling knowledge that may place the spillover occasion exactly within the southwestern nook of the Huanan market, and genetic testing of virus samples from the primary sufferers to present us a date: round November 18, 2019, for the introduction of Lineage B, with Lineage A following per week or so later. After that, although, the path runs chilly.
The researchers know which animals had been being bought available in the market in late 2019, and which of them had been inclined to coronaviruses, however they don’t have the smoking gun. “They don’t have samples from animals that had the virus. That’s what they’d prefer to have, and so they’d like to have the ability to hint these animals again to the farms from which they got here and see whether or not folks in these farms had been uncovered to the virus or viruses,” says Jonathan Stoye, a virologist on the Francis Crick Institute within the UK, who was not concerned within the analysis.
That’s unlikely to be attainable. There are theories on how contaminated animals could have reached the market: Wuhan is in Hubei province, and to the west of the area there are caves which can be dwelling to horseshoe bats, near farms that after housed hundreds of thousands of raccoon canines and civets. The almost definitely course of occasions is one thing like: A bat contaminated with a novel coronavirus flies over a farm the place animals are being reared for meat. It poops, and viral particles infect one of many animals under, sparking an unseen wave of infections on the farm. Perhaps the virus crosses over to the farmworkers however fizzles out as a result of there’s not sufficient inhabitants density to maintain a human epidemic. Days or even weeks later, in November 2019, among the contaminated animals are shipped to the Huanan Seafood Wholesale Market, the place they’re bought at stalls within the southwestern nook. The virus crosses over to people no less than eight instances, possibly extra. The vast majority of these infections fizzle out with out spreading to anybody else, however two take maintain, begin to unfold. Not lengthy after that, dozens of individuals within the space begin to come down with a mysterious viral pneumonia.
However the animal or animals that carried coronavirus are nearly definitely lengthy lifeless: shipped off and bought for meat, or killed in one of many mass culls that befell in early 2020 because the Chinese language authorities clamped down on the dwell animal commerce. “It is extremely attainable that we are going to by no means have that pattern, that we could have missed our alternative,” says Worobey.
However there are nonetheless results in observe: tracing the availability chains for the stalls within the southwestern nook of Huanan market and discovering out which farms provided them; poring over the paperwork from the culls to seek out out the place the animals from that farm had been buried; exhuming the animals and sequencing their DNA to search for remnants of a coronavirus that appears nearly an identical to SARS-CoV-2.
It’ll want affected person work and worldwide cooperation in a troublesome setting—but it surely could possibly be the one solution to cease the subsequent pandemic. “These items should not inconceivable,” Worobey says. “So let’s have a look at all of the choices. Let’s join each single attainable dot that we will.”
Picture up to date on 8/4/22 at 11:17AM PST to incorporate the Wuhan Huanan Wholesale Seafood Market.