Faye Flam

The Search for Covid's Origins Is as Important as Ever

The possibility that the Covid pandemic started with a lab accident isn’t a conspiracy theory. Nor has science conclusively proven that it started in a Wuhan wet market. We simply don’t know — because China has set up numerous roadblocks to impede scientists’ ability to understand the origin of a pandemic that’s killed millions and shows no sign of ending.

Americans, however, have been channeling our outrage not at China’s evasiveness, but at each other for disagreeing on what conclusions to draw from the sparse and indirect data that China has made available. Even if there isn’t enough evidence to paint a definitive picture of Covid’s origin, though, there’s something to be learned by stepping away from the fray and looking at whatever clues we have.

A new report by Senate Republican staffers declares a lab leak the most likely origin of the pandemic, based on allegations of porous protection mechanisms in labs handling dangerous bat coronaviruses at the Wuhan Institute of Virology. The Senate staffers also cited gaps in the evidence for the competing theory — that SARS-CoV-2 jumped to humans from live animals being sold at the Wuhan seafood market, where early cases were concentrated. Meanwhile, an investigation by Vanity Fair and ProPublica relied on a translator to infer that cryptic internal communications pointed to some sort of safety breach at that lab in late 2019. Others jumped in to dispute his translation, but something important could still come out of studying what was said inside that lab.

Identifying Covid’s origin didn’t have to become so fraught. After two previous coronavirus outbreaks — SARS1 and MERS — definitive data on their origins were available to scientists, said Laura Kahn, a physician who had studied biological threats at Princeton’s program on science and global security before co-founding the One Health initiative, aimed at pandemic prevention. China stalled for four months after the SARS outbreak, she said, but scientists there collected critical data and eventually allowed international teams in to investigate. The Middle Eastern countries where MERS was spreading allowed similar data collection.

The MERS and SARS1 origins were found by testing animals for these viruses as well as testing humans for antibodies to them, she said. All evidence pointed to civets for SARS1 and camels for MERS. Antibodies to those viruses concentrated in people who worked with or around these creatures.

That’s very different from China’s behavior when SARS-CoV-2 broke out. Officials quickly cleared out the Wuhan market where early cases were found, before any suspect animals could be tested. Taking blood samples from lab workers and market workers early on could have led to antibody tests that would have given hard evidence one way or another. (If such samples were taken in Wuhan, they were never disclosed to the outside world.)

The reason the Wuhan Institute of Virology has come under scrutiny is that the closest catalogued relatives of SARS-CoV-2 came from bats, and the lab houses the world’s largest collection of bat viruses. Some researchers in the Wuhan lab alter these viruses in experiments — leading to novel pathogens, though scientists there insist they never collected or created SARS-CoV-2.

Outside teams did not get to tour the lab until 2021 and never obtained enough evidence to verify or disprove those claims. Nor did they get the complete inventory of viruses or the lab notebooks that would have detailed all the experiments done there.
So scientists have been working with more indirect data — samples of the virus Chinese scientists say they took from the Wuhan seafood market around Jan. 1, 2020, as well as social media data showing where people were experiencing symptoms early in the outbreak. An investigation piecing together that data led to two different papers published in the journal Science last summer.

I talked to one of the authors of both papers, virology professor Robert Garry of Tulane University. He told me that the social media data showed the market as an epicenter of symptoms likely tied to early cases. And even more important, samples taken from the Wuhan market found SARS-CoV-2 around stalls known to have harbored live animals.

He also said that scientists who studied the genetic codes of these early viral samples found that the virus split into two distinct lineages, A and B, in host animals — followed by at least two separate jumps into people. Garry says it’s extremely unlikely that two separate jumps to humans would have happened in a lab; but if groups of infected animals were being handled in the market, the two strains of Covid could have infected humans there.

Critics have contended that the samples taken from the market might have come from humans, not animals, and that the initial infection could still have happened in a lab accident. The two lineages might have split off from each other while the virus was circulating in people — and eventually both ended up in the market. The mildness of many cases could have allowed it to simmer undetected for weeks. But Garry said that isn’t likely from the data they got from China on banked blood, which was all negative for antibodies to the virus in the months leading up to the discovery of the outbreak.

These studies have convinced some virologists that the virus probably started in the Wuhan market. Others are still skeptical. Some question the integrity of the data — and indeed, the data would be a lot more convincing if the researchers had been able to gather it themselves rather than having to rely on what Chinese government scientists sent them.

Another big problem: China never revealed what kinds of animals were in the stalls and cages where their data showed virus was concentrated. That would have been a critical clue, as investigators could have looked for infection in those species.

In short, whether the lab leak is the more likely scenario depends on which lines of evidence you choose to believe or emphasize. Accepting the Wuhan market theory of the virus’s origins requires putting a lot of trust in the limited data China has supplied. And remember, the Chinese government’s official version of events is that SARS-CoV-2 arrived in their country on frozen food imported from elsewhere — without blaming any specific country.

Debate should focus on the science — the quality of data and inferences drawn from it. There’s no conspiracy needed for the virus to have come from a lab leak or a market. China’s destruction and withholding of evidence has kept the answer hidden. But we shouldn’t give up trying to find it.