This transmission electron microscope image shows SARS-CoV-2—also known as 2019-nCoV, the virus that causes Covid-19.
CNN  — 

A Republican-led investigation into the origins of Covid-19 has unearthed additional, though circumstantial, evidence supporting the theory that the virus likely escaped from a lab in Wuhan, China, but it did not find any “smoking gun” evidence to prove the theory, according to a new report released on Wednesday.

Sen. Marco Rubio, the top Republican on the Senate Intelligence Committee, initiated a probe into the origins of Covid-19 nearly two years ago and the report released Wednesday by his office argues that new information discovered by congressional investigators adds to the credibility of what is known as the “lab leak theory.”

At the same time, the report acknowledges that Rubio’s probe did not unearth “smoking gun” evidence proving the virus emerged from a laboratory accident rather than emerging naturally in the wild – echoing what top US intelligence officials told lawmakers earlier this year about how there are still conflicting views about the true origins of the pandemic.

“What we present below is a substantial body of circumstantial evidence that supports the plausibility of such a scenario,” the executive summary of Rubio’s report states about the lab leak theory, making clear the findings do not offer a definitive answer to the origins question.

Specifically, Rubio’s new report highlights evidence that Chinese government officials and relevant figures in the scientific community “possessed some level of awareness of an outbreak of infectious disease” well before that information was disclosed publicly on December 31, 2019.

It also notes that the congressional investigation unearthed information that further suggests there was some kind of serious biocontainment failure or accident at the state-run Wuhan Institute of Virology during the second half of 2019.

This would have occurred “approximately during the same period of time in which the available epidemiological evidence indicates that SARS-CoV-2 was introduced to the human population in Wuhan,” the report says. SARS-CoV-2 is the name of the virus that causes Covid-19.

“In addition, indirect evidence suggests that the most senior leadership of the CCP (Chinese Communist Party) likely had at least limited knowledge of this laboratory incident by no later than the middle of November 2019,” the report adds.

Together, Rubio argues those findings provide an “aggregate picture” that strongly supports the lab leak theory.

In a statement Wednesday, the Chinese Ministry of Foreign Affairs called the report “a fabrication led by anti-China senators, which has no scientific credibility and is purely a deliberate smear and political manipulation.”

The ministry pointed to a 2021 report by the World Health Organization report, compiled by a team of international experts and their Chinese counterparts, that said the lab leak theory was “extremely unlikely.” However, the investigation drew criticism from governments around the world over accusations it was incomplete and lacked transparency.

“Instead of politicizing the issue of the origin of the new coronavirus,” the ministry said, “the U.S. senator should have worked with the World Health Organization to invite international experts to conduct research on the source and share the research results with the international community in a timely, open and transparent manner.”

US intel agencies split on origins of virus

While the FBI and Department of Energy have said in recent months they assess – with moderate and low confidence – that SARS-CoV-2 likely leaked from a lab, the majority of the intelligence community still believes that Covid either emerged naturally in the wild, or that there is still too little evidence to make a determination one way or another.

The various intelligence agencies have been split on the matter for years.

In 2021, the intelligence community declassified a report that showed four agencies in the intelligence community had assessed with low confidence that the virus likely jumped from animals to humans naturally in the wild, while one assessed with moderate confidence that the pandemic was the result of a laboratory accident.

Three other intelligence community agencies were unable to coalesce around either of the explanations without additional information, the report said.

The intelligence community provided an update to that report to lawmakers in February and the only significant shift compared to the 2021 findings was a new, low-confidence assessment from the Department of Energy in favor of the lab leak.

China’s Ministry of Foreign Affairs pushed back when asked about the reported assessment at the time. “The parties concerned should stop stirring up arguments about laboratory leaks, stop smearing China and stop politicizing the issue of the virus origin,” spokesperson Mao Ning said.

What the intelligence community and Rubio appear to agree on, however, is that the Chinese government is standing in the way of efforts to identify the true origins of Covid-19.

“Beijing’s efforts to render imperceptible the exact timing and original cause of the initial outbreak of SARS-CoV-2 are what necessitated this study,” Rubio’s report states.

“As its refusal to cooperate fully with the World Health Organization (WHO) has shown, Beijing’s efforts to keep these facts well beyond the world’s reach continue unabated,” it adds. “Scientists have not yet succeeded at tracing the origin because they have been denied access to the data that would facilitate a retrospective study of its genomic epidemiology.”

This story has been updated with additional information.