What a difference a year makes. In 2020, discussing the hypothesis that Covid-19 originated in a Chinese lab could get your video yanked from YouTube. Many journalists dismissed such talk as a conspiracy theory, and many scientists insisted it was fake science. Now these assurances are falling apart. The latest domino fell on Wednesday, when President Joe Biden shared the results of an intelligence community inquiry into the origins of Covid, which found that most intelligence agencies “do not believe there is sufficient information to assess” whether the virus came from a lab leak or from human contact with an infected animal. Biden announced he has given his spies 90 days to come up with a definitive answer. This new assessment undercuts a statement that the Office of the Director of National Intelligence issued on April 30, 2020. It said the intelligence community “concurs with the wide scientific consensus that the Covid-19 virus was not manmade or genetically modified.” And while the statement said that analysts will continue to study emerging evidence to determine whether Covid-19 came from a lab or occurred in nature, the political effect of the intelligence community’s intervention was to discredit former President Donald Trump, who had promoted the theory. So it’s worth asking how the lab-leak theory went from Trumpian misinformation to hypothesis that demands further study. There are a few factors. To start, some academic researchers who had kept out of this political debate began to speak up. On May 14, for example, the journal Science published a letter from 18 prominent scientists calling for a transparent investigation into the origins of the virus, explicitly saying that “we must take hypotheses about both natural and laboratory spillovers seriously.” In January, just before Trump left office, the State Department released a fact sheet confirming that in autumn 2019, several researchers at the Wuhan Institute for Virology became sick with symptoms similar to Covid-19 or seasonal illness. That fact undercuts claims from a senior researcher at the institute, Shi Zengli, who told Science magazine in July 2020 that there was “zero infection” among those studying coronaviruses in her lab. It also undercuts China’s claim that the first cases of Covid did not emerge until late December. As David Feith, who served as deputy assistant secretary of state under Trump, told me this week: “The main thing that motivated us to put out the January statement was the fact of the sick researchers.” And then there is the behavior of the Chinese government, whose resistance to the World Health Organization’s inquiry into the virus’s origins was such that even the China-friendly director-general of the WHO found his organization’s report lacking. For now, the Biden administration intends to press the WHO to perform a second, more serious study to account for the lab-leak hypothesis and prod the intelligence community to dig deeper. That’s all well and good. But neither approach will yield much clarity on the origins of the virus because the main obstacle is and has always been China, which as of this writing has yet to issue an official response to Biden’s announcement. It’s China’s government that has failed to grant researchers and scientists unfettered access to the Wuhan Institute of Virology and the blood samples of those who were first infected. It’s China’s government that first targeted the doctors, nurses and journalists who tried to warn their own country and the world about the outbreak. And it was China that initially denied in January 2020 that the virus could be transmitted between people. With that in mind, Biden should make an offer to Chinese President Xi Jinping: If you want to put an end to all this talk about Covid-19 originating in a government lab, then hand over the data the world’s scientific community has been demanding for nearly a year. If you continue to stonewall, then we will have to assume you have something to hide. It’s really that simple. China’s government can complain all it wants about the lab-leak theory. But it has the power to quiet its critics. All it has to do is open its lab and share its data. Bloomberg