There are two main theories about the origins of the COVID-19 pandemic. The first and the one most widely held by scientists is that a virus jumped unaided from animals to humans. The other is that it first emerged from a laboratory in Wuhan china where the pandemic started. Conspiracies have swirled around the chinese state backed lab is thought to have conducted research into diseases in bats. Multiple sources say this may be the costliest government cover up of all time by China. The lab leak theory has long been viewed as lacking credibility, one for the conspiracists or the cranks, but with some crucial questions still unanswered, the idea has been gaining traction. Yesterday, President Joe Biden asked his intelligence teams to look deeper into the pandemics origins, giving them 90 days to report back. In a statement, he suggested there was no clear view among those teams about which of the two scenarios was more likely. It's a muddy picture. When the World Health Organization visited Wuhan in february, it seemed to come down strongly in favor of zoonotic spillover that unaided jump. Yet the circumstantial evidence seems to be piling up like reports this week, the three researchers at Wuhan lab became ill a month before the outbreak and the seeming reluctance of chinese officials to help in getting to the truth. The theory of the lab origin keeps popping up for the simplest reason that the outbreak of COVID-19 started in the city of Wuhan, which also happens to house the world's center for bat coronavirus research. Natasha loader is our health policy editor. The first known site that SARS COv two emerged was efficient animal market in the city and it's no more than about 26 kilometers away from the Wuhan Institute of virology as the bat flies. It's also close to another center. The Wuhan Centers for Disease Control and both of these places worked with bat coronavirus is but we've spoken to a couple of times before about the origins of the virus and the lab leak theory has not been the one favored by the science that we've had. Yeah, that's right. And I say that that's still the case. What's changed really is that people are giving the lab leak hypothesis more credibility for what it's worth. My opinion has always been that a lab leak hypothesis was entirely possible and that sort of seems to be what the world is coming around to thinking as well. When we first covered this story, I co wrote it with Shashank, who is our defence correspondent and it was very clear from the biosecurity experts that we spoke to at the time that they felt a laboratory leak was not only possible, but something that was quite feasible given the number of lab leagues that had happened in the past of dangerous pathogens. So what's really changing is that by and large, I would say last year, mostly this hypothesis was treated as a sort of crank theory possibly because it was connected with the trump administration who are keen to push it, but also because it was tied to people who said that this was something that had been deliberately engineered by the chinese and that still remains quite a crank hypothesis. The idea that it was a bioweapon. What we're saying now is that, well, we know that at least two places in the city were working with back coronavirus is one actually was tinkering with them. And we know that lab leaks happen all the time. And so this needs to be given serious consideration. But when last we spoke to you about this, it was at the time of the World Health Organization's visit to Wuhan and a lot of questions then we're left unanswered. It was not clear that they had even come to firm conclusions themselves. That's right. When the scientists visited in february, they haven't made any firm conclusions. They certainly felt that a natural origin, some kind of spillover from wild animals was much more likely. But after they left china, in fact, just before they left china, they gave a press conference and they were really pressed on this lab leak hypothesis. And when they were in china, my impression was they felt obliged to say that they didn't think it was very likely. We also looked, for example, at the Wuhan Institute of Virology and the states of that laboratory and it was very unlikely that anything could escape from such a place. The media took the press conference and ran with a story that was the lab like hypothesis had been effectively ruled out that wasn't what they had said. And what was really interesting was that after the team had left china, the head of the rather unusually said that all hypotheses remained on the table and that was widely seen as meaning that he felt that the lively hypothesis needed to be considered as a possibility. And in fact, later he went on to the best way that he didn't think that it had been investigated well enough. And that was really the beginning, a moment when people kind of thought, okay, maybe this is something we do need to take more seriously. And since then we've seen a series of shifts with scientists kind of saying, ha ha maybe we should look into this a bit more. And one thing that's been fanning the flames this week anyway, apart from President Biden's statement is the claim that three workers from that Wuhan Lab fell in the month before the outbreak. These claims were first aired by the State Department in the dying days of the trump administration. And it's still not clear that these reports are actually accurate at all. And it's also probably no accident that these claims are surfacing again now because what's happening is that countries are gathering for the World Health Assembly. And this is where countries all get together to set the priorities for the World Health Organization in the coming year. And America wants another investigation. It wants to be seen to act firmly with china because politically, that's what it has to do. So it's useful for the biden administration to be seen as acting tough on china and pressing it over the lab leagues and pushing for another investigation. So how much of this question is now? Epidemiological, and how much of it political then? Yes, china, as you would expect, is very defensive on the issue and feels that it's politically driven. The Ministry of Foreign Affairs has even suggested that there are questions over the US's own bio labs and the reality is that if as far as had leaked from a laboratory, the Chinese government doesn't want this to be known and will have covered this up. So the idea that they're suddenly going to throw open their doors to a forensic investigation by outsiders is ludicrous, it's not going to happen. And then that leaves us in the position of wondering well, by pursuing this, that we're losing the opportunity to actually nail down a natural spillover event that happened. So it's a really curious position to be in. But this lab leak idea is getting more traction. You have always said it's at least entirely possible. What would it mean though? If it did prove to be true, what would change? What would change is that it would put an entirely new light on the whole scientific endeavor? And I think perhaps that's been the reason why scientists have been slow to accept this as a real possibility is that it's kind of too horrible really to think about. Very hard. And that is the idea that in actually trying to understand these viruses for good intentions to find out more about the next pathogen that could cause a pandemic in order to avoid it. The horrible reality might be that in the pursuit of a noble goal, you've ended up causing this terrible devastation. Now, let's just remember, it may be that this has had a natural origin, but if it didn't, then that's really got to kind of raise questions about how we pursue particular bits of work and how we justify it as well. Thanks very much for joining us, Natasha thank you so much, Jason.