Editor’s note, May 25, 2021: An editor’s note was originally added to this piece in April 2020 to acknowledge the ongoing discussion of the “lab leak” theory, but updates to the piece were not mentioned at the time. A new editor’s note was added on May 24, 2021, to acknowledge language changes that were made last April and to clarify the current scientific thinking around the lab leak theory, which has continued to evolve.
Editor’s note, May 24, 2021: Since this piece was originally published in March 2020, scientific consensus has shifted. Now some experts say the “lab leak” theory warrants an investigation, along with the natural origin theory. Some language in this article was updated in April 2020 to reflect scientific thinking, but it has not been updated since then. For our most up-to-date coverage, visit Vox’s coronavirus hub.
There are more and more signs that the coronavirus outbreak in the United States is spiraling into a large-scale crisis. The decisions federal and local public health officials and individuals make right now — to test more people with symptoms, inform the public about the risk, isolate the sick, and institute social distancing measures like canceling events — are crucial. So will the speed at which they execute them.
Meanwhile, in some right-wing news outlets and on social media, a dangerous conspiracy theory about the origin of the health crisis won’t die.
There are two main versions of the rumor, and they have one common thread: that the coronavirus, SARS-CoV-2, originated in a level 4 (the highest biosafety level) research laboratory in Wuhan.
In one version of the rumor, the virus was engineered in the lab by humans as a bioweapon. In another version, the virus was being studied in the lab (after being isolated from animals) and then “escaped” or “leaked” because of poor safety protocol.
The Wuhan Institute of Virology is a real place, and the exact origin of the novel coronavirus is still a mystery, with researchers racing since the outbreak began to figure it out. But already, virologists who’ve parsed the genome and infectious disease experts who study coronaviruses say they have enough evidence the virus is brand new and came from nature. A large group of them, citing genome analyses from multiple countries, recently affirmed in The Lancet that the virus originated in wildlife.
The emergence of the virus in the same city as China’s only level 4 biosafety lab, it turns out, appears to be pure coincidence.
Conspiratorial claims about the Wuhan lab are circulating on cable news and social media
Before we get to debunking, let’s note who is spreading rumors about the origins of the virus.
First, several prominent US conservative pundits and politicians — known to regularly spew nonsense (and bash China) — have been politicizing the bioweapon rumor for weeks.
“It probably is a ChiCom laboratory experiment that is in the process of being weaponized,” right-wing radio host and Presidential Medal of Freedom recipient Rush Limbaugh said of the virus on February 24. “All superpower nations weaponize bioweapons.”
The Arkansas senator furthered “infodemic” by pushing debunked claim that the novel coronavirus may have been created in a Wuhan laboratory. https://t.co/oJvVzjOyxw— Atlantic Council (@AtlanticCouncil) March 1, 2020
Former White House strategist Steve Bannon went on Fox News to defend Cotton and imply that the Chinese Communist Party was still hiding something about the origin of Covid-19. “The mainstream media and far left [are] saying, ‘Oh, he’s a conspiracy theorist,”’ Bannon said. ”All he’s saying: It’s incumbent upon the Chinese Communist Party and President Xi [Jinping] to come out and give all information ... this is all Cotton’s saying.”
In the New York Post, Steven Mosher, a regular critic of China’s population control measures, has stoked the leakage rumor, using an array of circumstantial clues that Chinese labs’ handling of deadly pathogens can’t be trusted.
Similar rumors have also been running rampant in online forums in China. The South China Morning Post on February 20 debunked yet another rumor of the virus escaping from the lab in China:
More rumours swirled online over the weekend, this time that [Wuhan Institute of Virology] researcher Chen Quanjiao had reported the head of the institute, Wang Yanyi, claiming she had “sold experimental animals” to the live animal and seafood market and “leaked the virus” from the lab.
But Chen denied the claim, saying she was angry that her name had been used to fabricate information. “The recent rumours about the institute have affected the researchers as they try to tackle key problems,” Chen said in a statement.
The scientific evidence disproving these rumors matters because the conspiracy theory could persist and undermine trust in public health authorities at this critical moment. As the Washington Post reported, the rumor that the virus came from a Chinese lab is one reason residents of one Alabama county are currently unnerved and distrustful of the response to Covid-19 in their state.
“Conspiracy theories about manmade viruses are not new. We saw this with HIV — the rumor that the US made it and introduced it into Africa. But they are really dangerous kinds of things to get spread around,” Gerald Keusch, a professor of medicine and international health and associate director of Boston University’s National Emerging Infectious Diseases Laboratories, told Vox.
So let’s walk through what we know about the virus, and why it’s time to put the lab rumor to rest.
The virus originated in bats and then jumped to humans, perhaps through other animals
Soon after the Chinese government acknowledged there was an outbreak of a mysterious new virus in late December in Wuhan, scientists raced to sequence its genome. By mid-January, they had it and shared it with the World Health Organization.
Soon after that, scientists saw that the virus closely resembled viruses that circulate in bats. “If you look at the genetic sequence of the virus, it’s closely related to a bat virus, about 96 percent the same,” Jim LeDuc, head of the Galveston National Laboratory, a level 4 biosafety lab in Texas, told Vox. “There’s been talk about a pangolin intermediate host; that’s probably not true.”
Chinese officials also reported that several of the first cluster of cases had ties to a live animal market where both seafood and other wildlife were sold as food. (The market has since been closed.) The market soon became the leading hypothesis for how the virus made the leap into humans, where it’s been able to spread efficiently ever since.
The genetic evidence and epidemiological information, according to three esteemed infectious disease researchers writing in the New England Journal of Medicine, “implicates a bat-origin virus infecting unidentified animal species sold in China’s live-animal markets.”
According to a genome analysis by Tanja Stadler from the Department of Biosystems Science and Engineering at ETH Zurich in Basel, the virus first began transmitting in humans in China as early as the first half of November 2019.
“The widespread hypothesis that the first person was infected at an animal market in November is still plausible,” Stadler said in a statement. “Our data effectively rule out the scenario that the virus circulated in humans for a long time before that.”
LeDuc agrees with the hypothesis that the animal market played a role in the virus jumping to humans. “The linkage back to the market is pretty realistic, and consistent with what we saw with SARS,” said LeDuc. “It’s a perfectly plausible and logical explanation: The virus exists in nature and, jumping hosts, finds that it likes humans just fine, thank you.“
Unfortunately, there’s a long history of these “spillover” events, where an emerging disease jumps from wildlife to humans, turning into a pandemic. And scientists say we should expect them with more travel, trade, connectivity, urbanization, climate change, and ecological destruction, if we don’t stop the drivers.
What researchers have to figure out now is how exactly the coronavirus jumped to humans: perhaps through a human eating an infected animal, or through humans being exposed to infected feces or urine. “All we know [is] its likely distant source was bats, but we don’t know who was between bats and people,” said Vincent Racaniello, a professor of microbiology and immunology at Columbia and host of the This Week in Virology podcast. “It could be a direct infection [between bats and humans] as well.”
A scientific paper in a major journal shows this is a genuinely new virus, and there’s no way it could have been engineered by humans
In a recent podcast episode, Racaniello discussed with two other researchers a fascinating paper about the virus origin. The key finding: that SARS-CoV-2 is “not a laboratory construct nor a purposefully manipulated virus.”
The paper, published in Nature Medicine on March 17, is written by several leading microbiologists who closely examined the SARS-CoV-2 genome.
Specifically, they found the unusual biochemical features of the virus could only have come about two ways after the virus jumped from animal to humans, or what’s called zoonotic transfer. The ways, they write, are: “1) natural selection in a non-human animal host prior to zoonotic transfer, and 2) natural selection in humans following zoonotic transfer.”
In other words, nature came up with these weird characteristics in the genome, either in an intermediary animal between bats and people or in humans after the virus infected one. As Racaniello put it on his podcast: “Humans could never have dreamed this up.”
What’s more, he noted, no known lab anywhere in the world was working on a coronavirus like this one, and its closest relative is a bat virus found in a cave in 2013 in Yunnan, China, 1,000 miles from Wuhan.“Presumably there’s a common ancestor, most likely from a bat or an intermediary animal that was contaminated by that bat,” Racaniello says.
The coronavirus would be a bad bioweapon
Several experts told me the theory that the virus was meant to be a bioweapon doesn’t make sense, either. One big reason: Covid-19 isn’t all that deadly or transmissible, compared to other potential pathogens out there.
“To make it as a bioweapon, if that’s what you wanted to do, there are scarier and more virulent pathogens to work with,” said Keusch of Boston University.
For instance, Ebola and the West African Lassa virus are deadly threats that can only be studied in biosafety level 4 labs, like Wuhan. Crimean-Congo hemorrhagic fever is a tick-borne disease that has a death rate of 30 to 50 percent. The global death rate for Covid-19, meanwhile, is around 3 percent at the moment, but it’s expected to come down dramatically as more cases are discovered in the coming weeks. And even now, it varies widely by country and region.
Simply put, if you wanted to release a bioweapon to kill a lot of people, there are much deadlier pathogens you could use.
The Wuhan lab has the same safety protocols as top biosafety labs in the US and Europe
In his article in the New York Post, Mosher suggests that we shouldn’t trust the officials who ran the Wuhan lab. “It sure sounds like China has a problem keeping dangerous pathogens in test tubes where they belong, doesn’t it?” he says.
I asked LeDuc, who runs the Galveston biocontainment lab, if he has any experience with the Wuhan lab. Turns out he has a lot. He and his colleagues have worked for six years with the Chinese team there, both in advising them on building their lab and keeping it safe, and on scientific collaboration. “I can tell you that lab in Wuhan is equivalent to any lab here in the US and Europe,” he said.
For instance, many labs now use radio waves to track and inventory vials containing dangerous pathogens.
Keusch agrees. “I don’t think there’s any likelihood that the lab is less prepared in terms of protocol and capability than any lab in the US. It’s really good, though nothing is perfect,” he said.
The rumors have also reportedly hurt the lab’s ability to do its work.
“The rumours … have caused severe damage to our researchers who have been dedicated to working on the front line, and seriously interrupted the emergency research we are doing during the epidemic,” the lab said in a statement, according to the South China Morning Post.
Why we need to figure out all the details of where the virus came from
According to Bruce Aylward, an epidemiologist who led the World Health Organization’s recent mission to China to assess its Covid-19 response, the investigation into where and how the virus jumped to people is ongoing. The focus remains on the (now closed) Huanan Wholesale Seafood Market, the wildlife market inside it, and other area markets.
“Ever since SARS, the market authorities now have to record which animals are sold by whom and where they come from in these markets. So now there’s a list of 10 vendors from seven provinces,” he told my colleague Julia Belluz in a recent interview. “Then China’s CDC can do a case control study based on where in the market these animals were.”
The focus in the past month has been on saving lives, he said, but as new cases and deaths decline, the investigators will eventually be able to turn back to getting animal info from the market vendors and testing the animals.
Racaniello says it’s critical that the source is identified to eliminate the chance that the virus is introduced into people again.
For LeDuc, China’s experience with the coronavirus should be a clear message of the great public health threat live animal markets post.
“The reason we’re seeing [coronaviruses like SARS and SARS-CoV-2 emerge] in China is they have these live animal markets, where they bring in animals alive and co-house them, one cage on top of another, where there’s an opportunity for transmission between atypical hosts,” says LeDuc.
We’ll need to be patient for Chinese investigators to get to the bottom of how the virus made the jump from animals to humans. In the meantime, remember that in a public health crisis, conspiracy theories are a distraction. Rather, it’s our collective responsibility to stay focused on keeping each other safe.
Correction: An earlier version of this story misidentified Tom Cotton’s position in Congress. He is a US senator.