The Covid-19 virus most likely leaked from a laboratory in Wuhan, China, according to the US Department of Energy.
A report seen by the Wall Street Journal said the agency had updated its position in light of “new intelligence” and the latest science on the virus.
He previously said he was “undecided” about how the pandemic started, adding that his new stance scientifically speaking stands with “low confidence.”
The FBI previously came to the same conclusion with “moderate confidence,” while four other US agencies believe the pandemic was likely caused by natural transmission and two others remain undecided.
The report, which is said to have been delivered to the White House and senior members of Congress, also indicated that the virus was likely not designed as part of a weapons program.
Researchers have widely dismissed conspiracy theories that the virus was deliberately created at the Wuhan Institute of Virology, a laboratory known for conducting classified research in the city where the first cases were identified.
But a series of independent studies published in leading academic journals have said samples of the virus or its ancestors could plausibly have been collected elsewhere in China for further study in Wuhan.
Jake Sullivan, the White House national security adviser, said there was still a “variety of views” on the issue among US officials.
But the latest findings further undermine the World Health Organization’s insistence that the laboratory leak theory is “extremely unlikely.”
However, the head of the WHO, Tedros Adhanom Ghebreyesus, has said that all theories about the origin of the virus are still on the table and has asked Beijing to allow further investigation.
According to reports, the classified findings of the energy department said in 2021 that three researchers from the Wuhan institute involved in coronavirus research were hospitalized due to illness in November 2019.
In the absence of evidence from Chinese laboratories, a clear answer to the origin of the virus may never be found.
One major hurdle often cited by scientists is that tracing the ancestry of coronaviruses is extremely difficult, and it gets more difficult as time goes on.
Several close relatives of the Covid-19 virus have been found in bats and pangolins in China and Southeast Asia, but they have been found to frequently mutate while hopping from one animal to another.
Virologists at the University of Sydney said last year that the chances of finding a direct ancestor are “almost nil”, adding: “That ship has sailed.”
The primary responsibilities of the Department of Energy are energy production, national security, and sponsorship of scientific research.
While not directly involved in viral disease research, he oversees a network of 17 laboratories, including some that deal with advanced biology.
Mr. Sullivan added: “President Biden specifically requested that the national laboratories, which are part of the Department of Energy, be included in this assessment because he wants to use all the tools to be able to find out what happened here.”
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