Throughout much of the COVID-19 pandemic, health experts widely assumed the new coronavirus that has killed at least 3.7 million people worldwide got passed from an infected animal to humans, either in the animal’s natural environment or at a wildlife market.
Now they’re revisiting whether the virus known as SARS-CoV-2 that emerged in the Chinese city of Wuhan might have leaked instead from a lab where researchers were studying such viruses, and potentially altering them in ways that could make them more contagious. China and many leading U.S. health experts have long dismissed that possibility — which was pushed early on by then-President Donald Trump — but there has been a shift among some researchers. Just last week the White House called for an independent investigation.
Rasmus Nielsen, a professor of integrative biology at the UC Berkeley, was among 18 researchers from respected universities around the world who in a May 14 article in Science called for the scientific community to explore the lab-leak theory. We asked him why this is suddenly gaining interest. His responses, which have been edited for length and clarity, reflect his personal opinions.
Q: A year ago, everyone said the virus surely came from wildlife, perhaps through a Chinese “wet market” selling fresh produce, seafood and meat near where the first cases originated. What has changed since?
A: In some sense, not much has changed. I don’t think you’ll find many people who will say it’s impossible that it could have come from a lab. That was always on the radar screen. We don’t really know.
Q: After former President Donald Trump said as early as April 2020 that he believed the virus leaked from a Chinese lab, why did so many scientists argue otherwise?
A: When Trump came out and said it came from a lab and there was no publicly available evidence, that politicized it. It became much more difficult for scientists to come out and talk about it.
Q: After a World Health Organization research team put out a report in March deeming a lab leak unlikely but not ruling it out, why were scientists unsatisfied?
A: The WHO report did not include an investigation of the lab leak hypothesis — it was not part of the mandate and the report dismissed this hypothesis without any real data. Also, it did not do many of the standard analyses you would do to find the source of a new epidemic, including detailed contact tracing of the first individuals infected.
Q: Has anything new been learned this year that raises the possibility of a laboratory accident?
A: We know much more about what was going on at the Wuhan Institute of Virology. They were growing viruses on human cells, adding in elements of another virus, training viruses on human cells to see which ones are most infectious. When you’re doing that, you risk making viruses that are more infectious.
Q: Is there evidence the COVID-19 virus was manipulated in a laboratory rather than simply a naturally evolved pathogen?
A: There’s not the scientific evidence one way or another. There’s nothing in the DNA sequence that’s a smoking gun. The sequence of SARS-CoV-2 is consistent with evolution in the natural world.
Q: What about conflicting reports of the Wuhan lab manipulating coronaviruses with “gain-of-function” methods, in essence intentionally making the viruses more virulent, which they deny?
A: In some sense, it’s a matter of semantics. Technically there’s no evidence of gain-of-function research, but there is evidence of genetic manipulation of coronaviruses in labs. They have published papers that showed they are working on chimeric (man-made) viruses.
Creating a chimeric virus may not be a gain-of-function experiment. You don’t necessarily purposefully insert something into virus that you know will make it more efficient or infectious. You might simply mimic the natural way natural viruses recombine with each other.
Q Would it be hard to tell from the virus’s genetic sequence whether it was a chimera?
A Yes, that is right. Some ways of doing this work would leave no clear traces in the DNA (RNA) sequence.
Q: Why do that kind of work?
A: The reason you do this kind of research is you want to know what viruses are out there that can cause an epidemic. To answer that, you need to grow them on human cells. So when this research is being done, it’s not just by crazy scientists doing mad experiments. It’s to be prepared for the next epidemic. That’s going on all over the place. But it should be done under conditions that are safe.
Q: Was the Wuhan Institute of Virology laboratory, a biosecurity level 2 out of 4, safe for that work?
A: I personally think that safety level is too low for that kind of research. It should be done in a BSL-3 or BSL-4 lab. The fact that it was being done in a BSL-2 is a worry.
Q: The COVID-19 virus hasn’t been found in animals. Does that suggest a lab leak?
A: We haven’t found such a thing for SARS-CoV-2, that’s right. But that in itself doesn’t prove anything. There are viruses we still don’t know where they came from. We never figured out where Ebola came from. There have been many lab leaks through time. SARS-1 escaped from a lab five times. But what’s never happened before is a new virus from a lab leaking.
Q: Does the speed at which COVID-19 vaccines were developed change the view of the benefit of this virus research?
A: The wonderful, fantastic thing is we have RNA vaccines. All you need is the genome of the virus. That’s also an argument that you don’t need research on these viruses. You can make a vaccine really, really fast without having that research in advance.
Q: Would the world and the scientific community have handled the virus differently if we knew from the start that it was manipulated and leaked out of a laboratory?
A: I think that would all be the same.
Q: Why is it important to find the answer to its origins?
A: The reason we need to know is to prevent COVID-23 and COVID-26 and COVID-29. In order to do that, we need to know how does it start. We want to know exactly how this transmission happened.