Early last year, New York Times science writer Donald G. McNeil Jr. reported on a controversial theory about the coronavirus that had begun to sweep around the planet — that it may have started in a laboratory in Wuhan, China, not as a random and naturally occurring pathogen.

The “lab leak” theory — disputed then as now — challenged the semiofficial thesis that the virus had jumped from an infected animal to a human in a food market in Wuhan. Allies of President Donald Trump had pushed the theory, casting doubt on statements by officials of China’s ruling Communist Party.

Yet the Times never ended up publishing McNeil’s 4,000-word story, after what he called “a good-faith disagreement” over scientific concerns, the complicated nature of the evidence and questions about the political motives of the mostly anonymous sources who were promoting it at the time, he later wrote.

In hindsight, the decision looks fortuitous. McNeil, while open to the possibilities and following many leads, ultimately came down on the skeptical side. “New Coronavirus Is ‘Clearly Not a Lab Leak,’ Scientists Say,” as he tentatively headlined it — a conclusion that now appears to be not very clear at all.

In the absence of crucial evidence of how the new coronavirus began comes many theories — one is that the virus accidentally escaped from a lab in Wuhan, China. (Sarah Cahlan, Meg Kelly/The Washington Post)

Since last year, the lab-origin story has gained new converts and respectability, despite China’s denials — in part thanks to journalists such as McNeil (who later left the Times amid an unrelated controversy) who have taken a fresh look at the limited evidence that has dribbled out over the past year.

The journalistic reconsideration of the lab story has been told not just in probing new stories — The Washington Post has published five stories about it on its front page in the past 2 1/2 weeks, some prompted by President Biden’s order of a 90-day review of the theory by intelligence agencies — but in corrected headlines and in editors’ notes affixed to last year’s stories. New information often casts out old, but it is unusual for news outlets to acknowledge so publicly that they have changed their understanding of events.

The retroactive takes seem to raise a theoretical question: Were news reports diminishing or disregarding the lab-leak theory actually “wrong” at the time, or did they in fact accurately reflect the limited knowledge and expert opinion about it?

To some pundits, the early dismissals of the lab thesis now look like media malpractice. “The media’s credibility is taking yet another hit,” Dan Kennedy, a veteran media critic and college professor, wrote earlier this month. He suggested the alleged mishandling of the story last year “may make it that much harder to persuade Trump supporters to get over their skepticism about vaccinations.”

But that analysis has the great advantage of hindsight. Many scientific experts were dismissive of the leak theory at first, thus validating the early skeptical reporting. As with any story that is new, complex and evolving, conventional wisdom undergoes a metamorphosis as new information arrives.

The first news reports about a potential lab accident in Wuhan as the cause of the outbreak were speculative at best. The Daily Mail appears to have been the first major Western publication to suggest the virus had a human origin. In an online story published Jan. 23 of last year, just a few weeks after Chinese officials disclosed the existence of a mysterious illness, the Mail wrote that “scientists warned in 2017 that a SARS-like virus could escape a lab set up that year in Wuhan, China, to study some of the most dangerous pathogens in the world.” It presented no evidence of a new “escape.”

The story was followed three days later by one in the Washington Times, which added a new wrinkle — that the facility, the Wuhan National Biosafety Laboratory, may have conducted bioweapons research in conjunction with the Chinese military. Its story hinged on a quote from Dany Shoham, an Israeli bioweapons expert, who hinted vaguely that “certain laboratories” in the institute “have probably been engaged” in covert bioweapons research.

The stories energized widespread discussion of the lab-leak theory on social media, which quickly became meshed with theories about bioweapons research — a strain of speculation that scientists still strongly discount. Within days, Facebook began warning users about spreading “false or misleading” information about the virus’s origins.

Nevertheless, the lab theory soon found an influential and mediagenic champion: Sen. Tom Cotton (R-Ark.), who suggested at a Senate hearing that the virus may have originated in a Wuhan “superlaboratory” and then appeared on Fox News programs hosted by Laura Ingraham and Maria Bartiromo to repeat his suspicions.

But other mainstream media outlets tended at the time to side with the doubters — of whom there were many, including the World Health Organization and 27 scientists who wrote in the Lancet medical journal strongly condemning “conspiracy theories” about human involvement in the virus’s creation. (One of the organizers of the statement was later revealed to be the head of an American organization that has funded the Wuhan lab.)

NPR reported in April 2020 that there was “virtually no chance” that the coronavirus was released from a laboratory in China “or anywhere else.” Such an accidental release, it said, “would have required a remarkable series of coincidences and deviations from well-established experimental protocols.”

Other articles and headlines characterized the theory as “false” or “debunked.”

But many of those news organizations have begun to amend their approach in light of a shifting consensus.

The Post originally described Cotton’s remarks as “debunked” and a “conspiracy theory” in a February 2020 article. But last week, The Post rewrote the article’s headline, softening “conspiracy theory” to “fringe theory” and noting that scientists have “disputed” it rather than “debunked” it. A correction said the article had “inaccurately characterized” Cotton’s comments “because, then as now, there was no determination about the origins of the virus.” Post managing editor Cameron Barr said “questions from readers and others” prompted a reexamination of the story.

Vox, the explanatory news site, acknowledged last month that it amended without notification an article it published in March of last year that came out strongly against the lab theory. The changes softened the original article’s assertions. Vox said in an editor’s note that it changed the story “to clarify the current scientific thinking” about the theory, “which has continued to evolve.”

Some of these corrections and clarifications have been seized upon by critics as evidence of a major misfire by the mainstream media. Yet a review of last year’s stories finds a largely cautious approach, relying on what expert sources had to say at the time, and the corrections have been few. And the media coverage was hardly monolithic, with a number of columnists (including Josh Rogin, a foreign-policy writer for The Post’s Opinions section) and other writers keeping the alternative theory alive by examining supportive evidence and noting what was not known.

Some of the reluctance to embrace the lab theory more fully may have been driven by the suspicion that Trump had promoted it to shift the blame to China from his administration’s chaotic response to the pandemic. Trump had suggested the pandemic was a Chinese plot to derail his reelection, and there were racist overtones in his repeated characterization of covid-19 as the “China virus” and “kung flu.” The administration’s credibility was further undercut when then-Secretary of State Mike Pompeo alleged there was “enormous evidence” of a lab origin but then declined to release any, even after Chinese officials challenged him to do so.

Peter Hotez, a global health expert and dean at Baylor College of Medicine, argues that journalists, rather than actively suppressing lab-leak theories, merely reacted warily to Trump’s “outrageous statements” by shying away from any reporting that might promulgate his “disinformation campaign.”

The story largely faded from the mainstream media’s radar as the pandemic’s toll grew and the presidential campaign amped up over the second half of 2020. Despite the occasional piece soberly examining its merits — including a probing January report in New York magazine and a September report in Boston magazine — the topic was largely the province of polarizing figures such as Fox News host Tucker Carlson.

A kind of tidal change began early last month, seemingly set in motion by two events.

The first was a lengthy review of the known scientific evidence about the lab theory by Nicholas Wade, a veteran science correspondent formerly with the New York Times. Writing in the Bulletin of the Atomic Scientists, Wade deemed the theory plausible and worthy of further investigation. He also excoriated Chinese officials, Western scientists and the news media, accusing them of muddying or suppressing information or merely being uninterested in looking further.

In short order, Science magazine published a letter from 18 scientists who called for an independent investigation. “We must take hypotheses about both natural and laboratory spillovers seriously until we have sufficient data,” they wrote. “A proper investigation should be transparent, objective, data-driven, inclusive of broad expertise, subject to independent oversight, and responsibly managed to minimize the impact of conflicts of interest.”

There was even a tentative bit of new information to chew on: The Wall Street Journal, citing U.S. intelligence information, reported on May 23 that three researchers at the Wuhan virology lab had sought medical care in November 2019, a few weeks before officials disclosed the outbreak at the market. (Some of the details in the Journal’s story had been noted in a State Department fact sheet that drew little attention when it was declassified in January.)

Matt Murray, editor in chief of the Journal, said that story was “carefully written to not make any bigger claim than what the evidence was,” though it was widely seized on as a sort of smoking-gun piece of evidence that the virus originated from the lab.

“We didn’t ignore the story, but we also didn’t dismiss it out of hand early amidst a big political debate around it. We were always open-minded in trying to follow the thread on the origins of the virus,” Murray said, describing a renewed effort by Journal reporters to probe the origin theory once the virus seemed to get under control in the United States, by the end of 2020 and the first few months of this year.

By then, McNeil, the former New York Times science writer, had grown more receptive to the lab-origin theory, if not entirely persuaded by it.

“The maddening aspect of this story is that — despite the big fuss being made right now — the facts on both sides are still incredibly thin,” he said in an email.

He added: “I don’t think anyone has yet gotten it right or wrong. I think it’s been an over-politicized year-long shouting match with very little hard evidence on either side. And it still is. This debate isn’t over, and it won’t be until more facts are unearthed — if they ever are.”

Murray said the Journal’s reporting has advanced the story and uncovered new information and clues. But, he said, “we’re not really closer to the answer of where the disease came from. The big question of what caused it is still out there.”