On Oct. 28, ProPublica and Vanity Fair published a story about an interim report on the origins of COVID-19 released by the Republican oversight staff of a Senate committee. The interim report was the product of a far-reaching investigation into the question of how the pandemic began, and we wanted to give readers an inside view of the team’s work and share independent experts’ views of its findings.

The debate over COVID-19’s origins has been contentious from the start, and the report’s conclusion that the pandemic was “more likely than not, the result of a research-related incident” triggered criticism. Scientists, China observers and others questioned the Senate team’s findings and our reporting about them.

Over the past several weeks, reporters and editors at both publications have taken a hard look at those criticisms.

Our examination affirms that the story, and the totality of reporting it marshals, is sound.

We re-interviewed some of our original sources and reached out to other specialists to address questions that were raised about the work we did to put in context the evidence cited by the interim report. In particular, we took a close look at how Toy Reid, a State Department political officer on loan to the committee, translated a Chinese Communist Party branch dispatch that was cited in both the interim report and in our story as evidence that staff at the Wuhan Institute of Virology (WIV) may have been responding to a biosafety hazard or breach.

We commissioned three Chinese language experts with impeccable credentials who were not involved in the original story to review Reid’s translation. They all agreed that his version was a plausible way to represent the passage, though two also said they would have translated the words to refer to the dangers of day-to-day lab operations. The third produced a translation that was in line with Reid’s. All agreed the passage was ambiguous. We have updated the story to underscore the complexity of interpreting that dispatch.

We have added additional context to the story. We have also identified two factual errors inconsequential to the premise of the story. They have been corrected.

It remains clear that in 2019, the WIV was addressing serious safety issues while scientists there faced pressure to perform. Risky coronavirus research took place in laboratories that lacked the maximum biocontainment safeguards, according to the interim report.

A series of WIV patents and procurement notices “suggest that the WIV experienced persistent biosafety problems relevant to the containment of an aerosolized respiratory virus like SARS-CoV-2,” the interim report says. On Nov. 19, 2019, the same day a senior government safety official arrived at the WIV to discuss what a meeting summary described as a “complex and grave situation currently facing [bio]security work,” the WIV sought to procure a costly air incinerator. One expert told us such equipment could be used as a “quick fix” if the HEPA air filtration system had failed in some way. A few weeks after that procurement notice, the WIV filed a patent application for an improved device to contain hazardous gases inside a biological chamber, like ones used to transport infected animals.

The interim report described the WIV’s struggles to find disinfectants that were effective enough to kill dangerous pathogens without corroding metal. In November 2020, with the pandemic well under way, the WIV filed a patent application for a new disinfectant. The patent said existing disinfectants corrode metals in ways that could allow pathogens to escape, “resulting in loss of life and property and serious social problems.”

The director of the WIV’s highest-level biosecurity lab acknowledged in September 2019 that some Chinese facilities researching dangerous viruses had “insufficient operational funds for routine yet vital processes.” Dr. Gerald Parker, a biosecurity health expert and adviser to the interim report, said he found such revelations “a recipe for disaster.” He added: “You further couple that with an authoritarian regime where you could be penalized for reporting safety issues. You are in a doom loop of pressure to produce, and if something goes wrong you may not be incentivized to report.”

We continue to see our story as a measured exploration of the array of questions raised about the WIV’s laboratories. The possibility that a biosecurity breach at the WIV occurred, and sparked the pandemic, remains plausible.

We plan to keep reporting on this issue and expect new evidence to emerge. It is our view that both the natural-spillover and laboratory-accident hypotheses for the origin of the COVID-19 pandemic merit continued investigation. Given the human toll, which continues to mount, it is imperative that we continue this work.

For those who want to know more details about our exploration of issues raised, our reporting methodologies and conclusions, we are providing more information below on:

More on the Translations and Interpretations

After the Vanity Fair-ProPublica story appeared online, questions began to emerge on social media about Reid’s translation of a key passage of a Chinese Communist Party branch dispatch dated Nov. 12, 2019, on the WIV website. According to Reid’s translation, it begins by pointing out that the lab works with dangerous pathogens and that once the test tubes are opened, “it is just as if having opened Pandora’s Box.” While the lab had “various preventive and protective measures,” it was nonetheless important to “avoid operational errors that give rise to dangers.”

The next phrase was the focus of the criticism. It appeared in bold letters in the interim report:

“Every time this has happened, the members of the Zhengdian Lab [BSL4] Party Branch have always run to the frontline, and they have taken real action to mobilize and motivate other research personnel.”

Our story shared Reid’s thought process. We wrote:

“Reid studied the words intently. Was this a reference to past accidents? An admission of an ongoing crisis? A general recognition of hazardous practices? Or all of the above?”

Reid recognized that there was an ambiguity in the phrase he translated as “Every time this has happened.” Did the word “this” refer to the daily dangers of doing experiments in a lab that handles deadly pathogens? Or did it point to the “operational errors that give rise to dangers”?

Before we published our story, Reid told us he found the passage to have a defensive tone. In the story, we quote Reid as concluding, “They are almost saying they know Beijing is about to come down and scream at them.”

Seven days later, on Nov. 19, a senior Chinese official arrived from Beijing to the WIV for a small, high-level safety training. A meeting summary said that the official had come bearing important oral remarks and written instructions from China’s senior leaders, including General Secretary Xi Jinping, related to “the complex and grave situation currently facing [bio]security work.”

To Reid, the mention of instructions from party leaders and reference to a “complex and grave situation” reinforced that the Nov. 12 dispatch was an attempt by the party branch to deflect criticism for something that had gone awry, as he explained.

We interviewed three experts on Chinese Communist Party communications before publication and shared with them the dispatches as they appeared in Chinese on the WIV website. We conducted the interviews on background to get their candid input. They expressed concerns regarding personal safety, given the sensitivity of the subject matter. All agreed with Reid’s interpretation that the safety training on Nov. 19, 2019, as described in the meeting summary, appeared to be urgent, nonroutine and related to some sort of biosafety emergency.

To assess the criticisms of Reid’s work that were raised after the story was published, we commissioned three Chinese translators, each with more than a decade of experience. One has translated for officials at the highest levels of the American and Chinese governments. We wanted their objective view of what the passage said, so we asked them to translate it and did not mention the interim report. After they had done that, we went back and asked them to review Reid’s translation from the report.

All three of their translations were different from one another’s and different from Reid’s. Yet, each agreed that Reid’s translation was one plausible way to translate the passage into English. Our translators looked at the Chinese characters that Reid had translated to read “Every time this has happened” and instead said they read them to mean “on such occasions” or “at every such an occasion.”

Before one of the translators was told what Reid had written, she said she thought the word “occasions” referred to when lab workers make mistakes that lead to hazards — an interpretation that mirrored Reid’s. The two others said they thought “occasions” referred to something more routine: opening test tubes for experiments. The language in Chinese, all three agreed, was ambiguous and could be read either way.

Some readers noted that the Nov. 12, 2019, passage actually appeared in August 2019 in a party publication. The existence of the earlier reference, they argued, proved that its repetition in November meant that it could not refer to a biosecurity emergency at that time.

We took a close look at the August 2019 post and asked our translators and the experts we consulted to do so as well. While the posts were very similar, the version uploaded on the WIV website in November 2019 was slightly different. It included additional language after the sentence that compared opening test tubes of viruses in the lab to opening Pandora’s box. The translator we commissioned who had the most experience rendered the additional language as follows: “These viruses are untraceable both coming and going, and although there are various protective measures, it is still necessary for lab workers to operate very carefully in order to avoid creating dangers through mishandling.” The translator was puzzled by the August post because without the language added in November, “it sounds as if they are leading the charge to open Pandora’s box,” she said. “If I were reading it, I’d be scratching my head.” That additional sentence, she said, “means that they go to the front lines to show everybody to be careful and not to cause errors that would be dangerous.”

One of the experts we consulted before and after publication, a former senior U.S. intelligence official, said the language added in November 2019 gave the post a defensive posture and was consistent with Reid’s analysis that party members were responding to some type of incident. The Chinese idiom that Reid translated as “come without a shadow and leave without a trace,” he said, “is a nice phrase to describe something that sneaked up on you and there was no way to defend against it. They’re basically saying to whoever this is being delivered to: ‘We didn’t see it coming. We did the best that we could to deal with the problem.’”

More on the Corrections and Added Context

There are two sentences in the story that have been corrected.

We reported that a Chinese military vaccinologist who had in the past collaborated with the WIV, Zhou Yusen, was the first to apply for a patent for a vaccine against COVID-19. The interim report stated that Zhou “was the first to patent a COVID-19 vaccine on February 24, 2020.” In fact, other researchers around the world sought patents before Zhou’s Feb. 24, 2020, filing.

However, it was the timing and nature of Zhou’s patent application and subsequent research papers that raised questions for interim report researchers.

In our review of early SARS-CoV-2 vaccine patent filings, the U.S. patent applications we found that predated Zhou’s were provisional applications, a number of which forecast experiments they planned to do in the future. Many of these applications were for vaccine candidates proposing to use a technology like mRNA. Such applications could be filed with the SARS-CoV-2 genetic sequence in hand and minimal experiment data.

By contrast, Zhou filed a full patent application for a different kind of vaccine that required more upfront work before its submission. Our story says, “In his patent application and in subsequently published papers, Zhou documented a robust research and development process that included both adapting the virus to wild-type mice and infecting genetically modified ones with humanized lungs.” We have updated the story to make clear why Zhou’s work stood out to the interim report researchers.

In our article, we quoted two independent experts and one adviser to the interim report about when they thought Zhou’s research was likely to have begun. After reviewing the patent and the papers, two said that they thought Zhou would have had to have started this work no later than November 2019. Jesse Bloom, a virologist at the Fred Hutchinson Cancer Center, said he believed Zhou’s timetable was feasible since his team had substantial expertise and ongoing work developing similar SARS-related coronavirus vaccines, but only if “everything went right.”

We have also corrected the sentence stating that Gabriel Gras was the last French expert at the WIV. We have learned that at least one other French scientist came to the WIV after Gras left.

Elsewhere, we’ve clarified language. Our story said that party officials at the WIV’s top biosafety lab “repeatedly lamented” the problem of “the three ‘nos’: no equipment and technology standards, no design and construction teams, and no experience operating or maintaining [a lab of this caliber].” We found two references to this concept in party branch dispatches on the WIV website in 2019. These Chinese Communist Party dispatches, we reported, “are often couched in a narrative of heroism — a focus on problems overcome and challenges met, against daunting odds.” We have updated the story to clarify that authors of those posts referred to the “three ‘nos’” as a recounting of problems from early in the lab’s construction that they said had been overcome, rather than a reference to ongoing struggles.

However, one of the experts on party communications we consulted saw the inclusion of the “three ‘nos’” in WIV dispatches as a telling sign that these serious problems from the beginning were “part of the DNA of this lab.”

On Whether the Lab Leak Is a Question Worthy of Exploration

Our story and the interim report pointed to a pair of oft-cited scientific analyses of COVID-19’s origins, one of which concludes that the pandemic was likely the result of multiple zoonotic events in which “two distinct viral lineages” of SARS-CoV-2 that had been circulating among animals at a Wuhan market infected people there.

Michael Worobey, an author on both papers, undoubtedly speaks for many when he says that natural spillover is “the only plausible scenario for the origin of the pandemic.” We repeatedly heard the perspective that the scientific case on the origins of COVID-19 is closed and that exploring the possibility that the coronavirus could have leaked from a Chinese laboratory is something no news organization or government official should take seriously.

We believe the opposite, that it remains an essential avenue for exploration to prevent future pandemics. And as interviews with other scientists before and after publication have made clear, the question is far from resolved. In their view, there is not enough evidence to establish how the virus first reached the now-infamous Wuhan market or to assert that zoonotic spillover is the sole possible explanation for the pandemic’s origin.

Bloom, the virologist at the Fred Hutchinson Cancer Center, is among those scientists. “I’ve never seen anything as controversial as this in my field,” he said. “The amount of toxicity is out of control. Each side feels uniquely wronged. To me, it remains an open question.”

The story noted that the interim report also left this question open: “The authors of the interim report do not claim to have definitively solved the mystery of COVID-19’s origin.” And the story also said the interim report is “no likelier” than studies of a zoonotic origin to “close the book on the origins debate, nor does it attempt to.”

Bloom believes the findings of the interim report and the story reinforce a need to continue to explore all possible causes of the pandemic. At the same time, he recognizes that the reactions to these investigations underscore the difficulty of having a dispassionate conversation about these questions. “Right now, this whole topic is so politically fraught, it’s hard for people to give objective assessments,” he said. “We may need an independent commission to get to the bottom of this.”