They called it a conspiracy theory. But Alina Chan tweeted life into the idea that the virus came from a lab.

Alina Chan started asking questions in March 2020. She was chatting with friends on Facebook about the virus then spreading out of China. She thought it was strange that people were saying it had come out of a food market. If that was so, why hadn’t anyone found any infected animals? She wondered why no one was admitting another possibility, which to her seemed very obvious: the outbreak might have been due to a lab accident.

Chan is a postdoc in a gene therapy lab at the Broad Institute, a prestigious research institute in Cambridge, Massachusetts, that’s affiliated with both Harvard and MIT. She had worked in a few labs and knew they were not perfect places. In fact, she had often been the one to speak up about what was wrong. She’d been involved in a whistleblowing complaint about working conditions in a lab at Harvard. (Both Chan and Harvard have declined to comment on the details.) Chan always seemed to be the one who took a stand, even if it didn’t bode well for her career. “I am stupid that way,” she says. “A born shit stirrer.”

The discussion on Facebook started when one of her friends posted a letter published by five senior virologists in the journal Nature Medicine, titled “The Proximal Origins of SARS-CoV-2,” which analyzed likely sources of the new virus. The authors of the letter had looked carefully at the genome of the covid-19 virus and said they couldn’t find any sign it had been purposely engineered. A friend told Chan the paper should “put to bed” all conspiracy theories. But when she read it, she could already see a problem. In debunking the possibility that the virus was the product of extensive genetic engineering, they’d ruled out other, simpler scenarios. For instance, a normal virus collected from bats in the wild, if brought to Wuhan, could have somehow slipped out.

“I was like, ‘They are very mistaken,’” says Chan. “They haven’t thought of all these other plausible ways for a lab leak to occur.”

Her view is now widely held. That’s due partly to her Twitter account. Throughout 2020, Chan relentlessly stoked scientific argument and doubts, sometimes adding a unicorn GIF to highlight research she found implausible. Many scientists quietly believed that a lab leak was possible—if only because the world center of research on bat viruses similar to SARS-CoV-2, the Wuhan Institute of Virology, happens to be eight miles from where the outbreak’s early cases were seen. But there wasn’t any real evidence, and it didn’t pay to “take on the big guys,” as one accomplished virologist told me.

Chan wasn’t afraid to pit her brain against the best virologists in the world and her persistence helped change some researchers’ minds. The reversal in thinking has been so sharp that media organizations are updating old articles having branded the lab-leak idea a conspiracy theory. One in Vox, for example, now explains that “the scientific consensus has shifted.” In May, President Biden ordered his intelligence agencies to carry out a new investigation into the origin of the virus. It’s due before the end of the summer.

“I think my goal has been achieved,” says Chan. “I just wanted people to investigate, take it seriously. My job is done, and I want to go back to a normal life.”

That’s not likely to happen soon.

Chan is in demand from television and radio programs and just signed a deal with HarperCollins to write a whodunit about the search for the origins of covid-19, working with the British science writer Matt Ridley. (Neither she nor Ridley would tell me how much the book had sold for.) She also has to bear the consequences of accusing China, in effect, of one of the biggest manslaughters in history. She told me that after the book is published, she plans to change her name and try to quietly continue her scientific career.

Chan has also attracted unwelcome and scary attention, like the messages she gets calling her a “race traitor.” Ethnically Chan is part Chinese, but she was born in Canada and grew up in Singapore, where her family is from. She says they are apolitical and her parents work in information technology. “Don’t get into trouble; don’t get into politics” was a motto around the house. Chan returned to Canada at 16 to attend the University of British Columbia for both her undergraduate degree and her PhD. Eventually she had to decide which nationality to keep, opting for her Canadian passport.

Before I met her recently at the Broad Institute, we arranged the meeting on the encrypted app Signal. She didn’t want to say what floor she worked on; we met outside the building. She’s told friends the Chinese government might be after her, saying: “My goal right now is to stay alive and not get hacked.”

“There are some safety concerns,” says her boss at the Broad, Ben Deverman. The Broad is the premier institute in the US for studying human genetics, with a budget of $500 million a year. Deverman’s lab investigates how to modify viruses that could be used in gene therapy. “I think she has probably done more than anyone in engaging the public and presenting things from a scientific and middle ground, which maybe didn’t seem like middle ground at the time,” he says of her commentary about the lab-leak theory. “Her view hasn’t changed, but other people’s have.” That includes people inside the institute, which has supported her freedom of speech but asked that she maintain some space between her work and her Twitter activities. “We see it as outside of what she gets paid for,” says Deverman. “As long as she didn’t speak for anyone but herself, it was her right to discuss and pursue this.”

“I am scared to even think of all the things that it implies, and what will happen if it’s found to be true,” says Deverman. “It is a little bit scary. I honestly don’t know how the world would handle that information, but it can’t all be good. ”

Like other journalists interested in the lab-leak idea, I have followed Chan since last May. She presented a unique figure among the online sleuths looking into the mystery. She worked at a real scientific institution and didn’t seem to be crazy or to have an obvious motive. She is smart and friendly and had countless references at her fingertips, which she always took time to share and explain. “There is no doubt that she has helped raise the lab-origin discussion to a level that more people are willing to talk about it, not just conspiracy theorists,” says Jonathan Eisen, who studies the evolution of microbes at the University of California, Davis, and is also active in social media discussions of covid origins.

The obvious problem with the lab-leak theory, though, is that there remains no concrete evidence for it. Chan has no particular view about how exactly an accident might have happened—whether a student got sick in a bat cave, say, or secret research to infect mice with a novel virus went awry. After reading Chan’s posts, I noticed that many of her claims don’t even relate to direct evidence at all; more often, they revolve around its absence. She tends to point out things that Chinese researchers didn’t do or say, important facts they did not quickly reveal, the infected market animal they never found, or a database that’s no longer online. She’s plainly suggesting there is a cover-up—and, therefore, a plot to conceal the truth.


Last February, when leading scientists convened to analyze the virus genome, they ended up publishing two letters. One, in The Lancet, dismissed the lab-accident possibility outright as a “conspiracy theory” (its authors included a scientist who funded research at the Wuhan lab). The other was the “Proximal Origins” letter in Nature Medicine, coauthored by Kristian Andersen, an evolutionary biologist at the Scripps Research Institute in La Jolla, California. Andersen and his coauthors looked at the genome of the virus and marshaled arguments for why it was very likely a natural occurrence—backed by evidence that it was similar to others found in nature.

The 30,000 genetic letters in that genome remain the most widely studied clue to the virus’s origin. Coronaviruses frequently swap parts—a phenomenon called recombination. Andersen found that all the components of the virus had been seen before in samples collected over the years from animals. Evolution could have produced it, he believed. The Wuhan Institute had been genetically engineering bat viruses for scientific experiments, but the SARS-CoV-2 genome did not match any of the favorite “chassis” viruses used in those experiments, and it did not contain any other obvious sign of engineering.                                                                                             

According to Clarivate, an analytics company, the Nature Medicine letter was the 55th most cited article of 2020, with over 1,300 citations in the journals tracked. Email records would later show that starting in January 2020, the letter had been the subject of urgent, high-level messages and conference calls between the letters’ authors, Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases; top virologists; and the head of the Wellcome Trust, a major pharmaceutical research funding organization in the United Kingdom. Early on, the authors had worried that the virus looked suspicious before quickly coming together around a scientific analysis supporting a natural cause. Initially one of their aims was to quash rumors that the virus was a bioweapon or a result of engineering gone wrong, but they ended up going further, writing: “We do not believe that any type of laboratory-based scenario is plausible.”

Working from her home in Massachusetts, Chan soon found a way to revive the lab-accident theory by looking for differences with SARS, a similar virus that broke out in 2002 but caused only about 8,000 illnesses. With Shing Zhan, a bioinformatics specialist at the University of British Columbia, Chan looked at the early human cases of covid and saw that the new virus hadn’t mutated as fast as SARS had. If it were an animal virus from a market, she thought, its genome would show signs of adjusting more quickly to fit its brand-new human host. She prepared an analysis arguing that the virus was “pre-adapted” to humans and offered some theories as to why. Maybe it had been spreading undetected in people elsewhere in China. Or maybe, she thought, it had been growing in a lab somewhere, perhaps multiplying in human cells or in transgenic mice that had had human genes spliced into them.

The chance that a non-engineered virus could have “adapted to humans while being studied in a laboratory,” she wrote, “should be considered, regardless of how likely or unlikely.”

On May 2, 2020, Chan posted a preprint paper, coauthored with Deverman and Zhan, to the website bioRxiv, an online venue for quickly communicating results that haven’t yet been reviewed by other scientists. “Our observations suggest that by the time SARS-CoV-2 was first detected in late 2019, it was already pre-adapted to human transmission,” they wrote. The Broad Institute communications department also pointed Chan to examples of how to compose a “tweetorial,” a daisy chain of posts, with pictures, that present a compact scientific argument to a wider public. She posted her first tweetorial the following day.

For journalists suspicious about China’s handling of the virus, the thread—and those that followed—were dynamite. Here was an actual scientist at America’s biggest gene center who was explaining why the official story might be wrong. “Coronavirus did NOT come from animals in Wuhan market,” screamed a Mail on Sunday headline, in what became Chan’s first breakout into the public conversation.

While her report was a media success, what the Daily Mail described as Chan’s “landmark paper” has still never been formally accepted by a scientific journal. Chan says that’s because of censorship due to her raising the lab-origin possibility. Eisen of UC Davis, however, thinks Chan’s expectations for how the covid-19 virus should have behaved remain conjecture. He doesn’t think we’ve traced enough outbreaks in enough molecular detail to really know what’s normal. And, he notes, covid-19 has continued to change and adapt.

“My colleagues said, This is a conspiracy—don’t bother. I said, No, I am going to treat this like any other paper,” says Eisen, who took time to study the manuscript. “I think it’s interesting what she tried to do, but I am not convinced by the conclusion, and I think the inferences were wrong. I do commend her for posting it. Many of the people pushing the lab-origin theory are not making claims based on logic, but she presented her evidence. I don’t agree with it, but that is science.”

Wrong or right, though, the word Chan used—“pre-adapted”—sent shivers up the spine of people like author Nicholson Baker. “We were dealing with a disease that was exceptionally good, right out of the gate, at chewing up human airways,” says Baker, who got in touch with Chan to learn more. Several months later, in January of this year, Baker would publish a lengthy report in New York magazine saying he’d become convinced a laboratory accident was to blame. He cited a variety of sources, including Chan.

Pangolin problem

Chan wasn’t done knocking holes in the natural-origins narrative. She next took on four papers that had been rapidly published early in 2020, two of them in Nature, describing viruses in pangolins—endangered scale-covered mammals sometimes eaten as delicacies in China—that shared similarities to SARS-CoV-2. If researchers could find all the components of the pandemic virus, especially in wild animals illegally trafficked as food, they could cinch the case for a spillover from nature, given the way coronaviruses swap parts. The pangolin papers, published in quick succession in early 2020, were a promising start. To the authors of “Proximal Origins,” these similar viruses offered “strong” and “parsimonious” evidence for natural emergence.

Chan and Zhan noticed that all the papers described the same batch of animals—even though some failed to acknowledge the overlap. One even relabeled the data, which made it appear novel. To Chan, that wasn’t just sloppy work or scientific misconduct. There could, she believed, have been “coordination” between the overlapping authors of all these papers, some of whom had published together before. She created the hashtag #pangolinpapers—calling to mind the Panama Papers, documents that exposed secret offshore financial dealings.

Maybe, she thought, researchers were now laundering data to make it seem that nature was swimming with similar viruses.

Chan started emailing authors and journals to get the raw data she needed to more fully analyze what they had done. Making such data available is usually a condition of publication, but it can still be hard to obtain. After what she calls months of stonewalling, Chan finally lost her cool and blasted an accusation out from her browser. “I need the scientists + editors who are directly or indirectly covering up severe research integrity issues surrounding some of the key SARS-2-like viruses to stop and think for a bit,” she posted to Twitter. “If your actions obscure SARS2 origins, you’re playing a hand in the death of millions of people.”

Eddie Holmes, a prominent Australian virologist and coauthor of one of those papers (as well as “Proximal Origins”), called the tweet “one of most despicable things I read on the origins issue.” He felt accused, but he wondered what he was being accused of, since his paper had correctly accounted for its pangolin data sources. Holmes then circulated an intricate time line prepared by Chan of the publication dates and past connections between the authors. The chart’s dense web of arrows and connections bore an unmistakable resemblance to an obsessive’s cork board covered with red string and thumbtacks.

Holmes did not respond to a request for comment. But after someone called the Broad Institute to complain of harassment, Chan took down the post. “I made the mistake of tweeting in anger,” she says. The Broad is an affiliate of MIT, which also publishes this magazine, and I found last year that Chan had angered key virologists so much that my roundabout institutional connection to her had become a problem. When I called Holmes last fall on a separate matter—to learn about the initial release to the public of the SARS-CoV-2 genome in January 2020, which he had facilitated—he replied that he would not discuss that with me because Chan is also affiliated with MIT and “has been directly challenging my research integrity.”

“Actions have consequences,” Holmes wrote me, declining the interview. “Sorry that you are collateral damage.”

Some of Chan’s followers on Twitter say the episode is telling. “I think she is more intellectually honest than many other strong lab-leak proponents, including some faculty. I like how she engages on the issues,” says Alex Crits-Christoph, who specializes in bioinformatic studies of genetic data, most recently at the University of California, Berkeley, and, like Chan, is a postdoc. “That being said, I think she has made some big mistakes here. I think her main mistake is in claiming malicious intent in situations where there are only the standard issues of big and messy sequencing projects.”

Viral genome

Crits-Christoph told me he also has spent countless hours crunching through gene databases on his computer looking for origin clues. He initially felt the odds of a lab leak were 20% but says that after studying the question, he has cut his estimate in half. The evidence of a natural origin just seems stronger. “There is an enormous bias toward the lab-leak hypothesis that nobody really admits to,” he says. “Which is that there’s a lot of us who would be ecstatic if bioinformatics could … lead to proving a crime straight out of a Michael Crichton novel.”

The SARS-CoV-2 genome clearly places the virus into a subfamily of pathogens seen in bats. It’s a piece of spare biological malware—not actually alive, but good at hijacking a cell and turning it into a factory for more virus. But despite assorted claims that it was constructed from HIV, or created with CRISPR, the genome carries no clear mark that it was born in a petri dish. In the opinion of many scientists, like Eisen, it’s instead just the sort of thing evolution could cook up—clever, compact, deadly effective, and a variation on themes seen before.

The lack of a smoking gun in the genome is one reason why, over the first half of 2020, the lab-accident theory mostly lived online, where it was pursued primarily by internet sleuths, some working under anonymous handles, who lacked credibility with mainstream scientists. “Overzealous activists, self-appointed detectives, unqualified writers, and politically motivated conspiracy theorists” is how the virologist and opinion writer Angela Rasmussen, of the University of Saskatchewan, would later describe the social circle that formed around theories about the virus’s origins.

These sleuths did have some success in one area. Using the Wuhan Institute of Virology’s own records, including a master’s thesis found on a Chinese website and annotations in gene databases, they documented the fact that the institute had not immediately disclosed a cache of viruses in the same family as SARS-CoV-2. It had also obscured where these other viruses had been found: in a mine where some men who’d been shoveling guano had died of a mysterious lung disease in 2012. Eventually, eight months later, the institute acknowledged the dead miners and tests that had been run on their stored blood. The tests, the institute said, ruled out SARS-Cov-2 as the cause of the 2012 deaths.

The failure of the institute to disclose such relevant information earlier is inexplicable to many scientists. “It’s hard to understand why they didn’t tell us before,” says David Relman, a Stanford University biologist. Anthony Fauci has also said he’d like to get a look at those miners’ blood samples.

Chan has sometimes acted as a clearinghouse for lab-leak clues, knocking down the loopiest ones but elevating others. Sometimes she has added scientific sinews and references. Other times, she has crystallized concerns with a pithy tweet. For instance, in its initial description of the virus, in February 2020, the Wuhan Institute failed to note an unusual component called a furin cleavage site, a bit of genetic sequence that is potentially suspicious because furin sites are sometimes intentionally added to viruses to make them more infectious.

The furin site, a string of four amino acids, helps the virus fuse to human cells. No such site is found in any of the other viruses that are most closely related to SARS-CoV-2. However, genetic engineers have a history of adding them in lab experiments. Speculation that the presence of the furin cleavage site is a signature of human genetic manipulation has made it one of the most scrutinized aspects of the genome. Chan sees the omission by the world’s top bat virus experts as damning. She has compared it to “describing a unicorn and not mentioning the horn.” She’s hammered at the point by posting dozens of GIFs of unicorns, adding sarcastic comments like “Looks totally natural to me.”

Put that way, the omission does sound very suspicious. Was it, though? Two other prominent papers that were among the first to describe the virus also failed to mention the furin cleavage site. But other researchers immediately found it in the genome, which was by then public anyway. To Stuart Neil, head of the department of infectious disease at King’s College London, the omission is definitely “odd,” but there are other, less sinister explanations. Maybe the researchers were just in a hurry, he says. “They didn’t hide anything; they just didn’t comment on it.”

Researchers have taken note of the one recurring implication of Chan’s commentary: that not only was there a lab accident, but China must be actively covering it up, with the unwitting help of foreign scientists too afraid to ask tough questions. “Any type of lab origin would have to involve a massive conspiracy of scientists, doctors, and public health responders,” Andersen, of the Scripps Institute, wrote in one of his many online criticisms of Chan, who would frequently spar with him on Twitter. Yet, Andersen noted, more than a year later, no credible whistleblower has emerged out of China.

Chan can come up with reasons for that. A lab accident doesn’t need to involve a lot of people. Plenty of research screwups get quietly cleaned up and never mentioned. Chinese police also tried to prevent doctors from discussing the virus; some citizen journalists have been packed off to prison for troublemaking. Anyone in China who accidentally released the virus, Chan says, would have ample reason to stay quiet, since “they could be killed.”

State department

By the end of 2020, Chan’s prominence was reaching an apex. As first reported in Vanity Fair, officials at the US State Department’s arms control division convened on Zoom on January 7, the day after the Capitol riot, to hear evidence on the odds the virus had come from a lab. Chan was one of two speakers chosen to address the group. The other was Steve Quay, a doctor and CEO of Atossa Therapeutics, a publicly traded biotechnology company that markets health books via a website. Quay has said he is “99% sure” the virus comes from a lab.

Chan told me she had initially resisted briefing the State Department and has been surprised by how little the US government actually knows. There don’t seem to be any secret wiretaps or defectors who are telling all. Instead, Trump-era investigators seemed to rely on tweeted evidence and sources who were not trained virologists. This resulted in an angry debate among officials about whether evidence was credible. Two leaked memos relate some of these debates. One of the memos defends Quay’s reliability on grounds that he is a “biotech entrepreneur with 78 patents to his name” and praises Chan for her “deep expertise of Chinese duplicity and lack of transparency.”

“I think that says more about them than me,” she says with a laugh. Chan has no particular expertise on China. Though she can read Chinese, which she studied in Singapore, her spoken Mandarin is poor enough that waiters will sometimes ask her to order in English. She also denies being motivated by any special animus against China. “I have never lived in China,” she says. “Neither of my parents even speak Chinese as mother tongue. I don’t even know anyone in China. I think my stance is as reasonable as it could be—I don’t like the Chinese Communist Party because of dictatorship and concentration camps. I could also criticize the US government for children in cages. But that doesn’t mean I want the US to burn either.”

Chan sent me a copy of her slide deck from the State Department briefing, with a listing of “Top 10 Points.” Of the 10, four are genetic or biological arguments, leading off with the missing period of virus adaptation in humans—even though this finding is not widely accepted. The other six relate to allegedly suspicious behavior on the part of Chinese scientists, including the failure to mention the miners who died in 2012 and the furin site on the virus genome. Any courtroom prosecutor would recognize these points as a circumstantial case for “consciousness of guilt,” the legal concept that covers actions like faking an alibi, destroying evidence, or threatening a witness. As Chan’s co-presenter, Quay, put it in his presentation, which covered similar ground, no “innocent” virologist would commit such oversights.

A terrible thing

By March 2021, China and the World Health Organization were ready to present the result of a joint, official origins investigation, which concluded that a bat virus caught from food animals was a likely cause and dismissed a lab accident as “extremely unlikely.” They reached that conclusion because of China’s claim that no one in the lab had contracted the virus or had ever worked with SARS-CoV-2 before. The investigation group said it would not pursue the theory any further, although that conclusion did not land well, even within the WHO, whose chief, Tedros Adhanom Ghebreyesus, responded to the announcement by saying all theories must remain open.

Chan by then had amassed a widening group of scientific allies who shared her suspicions or had their own. On April 1, she sent an email to Relman and Jesse Bloom, a virologist at the Fred Hutchinson Cancer Research Center, proposing that they organize a statement calling for a full investigation that would have access to open lab books in China and other raw data—just the kind she’d been denied with the pangolins. Now, with many scientists dismayed by the WHO report, 18 of them—including Relman, Bloom, and Ralph Baric, a top coronavirus expert at the University of North Carolina—agreed to sign on. With the weight of such senior names attached, in addition to Chan’s, the letter quickly appeared in the journal Science.

Since the letter’s publication, stances on the lab question have shifted even more rapidly. Numerous scientists have been publicly switching sides. One signatory of the 2020 Lancet letter denouncing the lab-leak hypothesis as a conspiracy theory has changed his mind entirely. He’s now sure the virus was released through a sloppy mistake somewhere in Wuhan. The letter also helped cleanse the lab theory of its link to Donald Trump, Fox News, and assorted Republican officials who had first enthusiastically aired it last year.

A few days after the letter’s publication, US President Joseph Biden ordered the intelligence report in view of the fact that intelligence agencies were split in their thinking. “I have now asked the intelligence community to redouble their efforts to collect and analyze information that could bring us closer to a definitive conclusion, and to report back to me in 90 days,” Biden said.

Now that the lab-origin theory is being investigated by powerful organizations and taken seriously by a critical mass of respected scientists, I asked Chan how she would feel if the virus did prove to have emerged naturally, which most scientists still seem to believe is more likely.

“I have days where I think this could be natural. And if it’s natural, then I’ve done a terrible thing because I’ve put a lot of scientists in a very dangerous spot by saying that they could be the source of an accident that resulted in millions of people dying,” she says. “I would feel terrible if it’s natural and I did all this.”

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