Intelligence agencies do not believe the case of three workers from a laboratory in Wuhan, China, who became ill in 2019 can help shed light on whether the Covid-19 pandemic originated from an accidental lab leak, according to a report made public Friday.

The Office of the Director of National Intelligence released a long-awaited declassified report, which included spy agencies’ findings on the so-called lab leak theory, but the material is unlikely to satisfy many people who have been wrestling with the unanswered questions on the origins of the Covid outbreak.

The 10-page report said scientists at the Wuhan Institute of Virology did conduct research on coronaviruses, in some cases had inadequate safety measures and had genetically engineered coronaviruses. But the intelligence agencies said they have found nothing that tells them that work at the laboratory caused the pandemic.

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“The I.C. has no information, however, indicating that any W.I.V. genetic engineering work has involved SARS-CoV-2, a close progenitor, or a backbone virus that is closely related enough to have been the source of the pandemic,” the report said, referring to the intelligence agencies’ findings.

The country’s intelligence community, which includes more than a dozen organizations across the government, has been divided over Covid’s origins: Two agencies believe a lab leak was more likely while five others favor natural transmission from an animal market as the most likely cause of the original Covid outbreak. The C.I.A. and another agency remain unable to determine the precise origin of the pandemic, given conflicting intelligence, the report said.

“All agencies continue to assess that both a natural and laboratory-associated origin remain plausible hypotheses to explain the first human infection,” the report said.

The illnesses of the three workers, first made public by the State Department at the end of the Trump administration, has been a focus of researchers, journalists and the intelligence agencies.

In August last year, intelligence agencies concluded that the case of the workers could not help analysts determine whether the lab leak or natural transmission was more likely.

Nevertheless, the case of the three workers has received additional attention in recent days. A Chinese scientist at the Wuhan Institute of Virology worked on coronavirus projects that were funded by the U.S. government and was one of three researchers who became sick in November 2019. However, U.S. intelligence agencies have not determined if the researchers had Covid or another illness with similar symptoms.

The report released on Friday reinforced the intelligence agencies’ views that the workers’ illness could not help shed light on the origins of the pandemic.

The workers fell mildly ill, but the report cast some doubt on Covid as the cause. The report cites findings from the World Health Organization that said investigators with China’s National Security Commission reported blood samples from the sick workers for Covid were negative. It is not clear from the report if intelligence agencies believe the work of the Chinese investigators, but the spy agencies do not believe the workers’ illness can help resolve questions of the pandemic’s origins.

“The I.C. continues to assess that this information neither supports nor refutes either hypothesis of the pandemic’s origins because the researchers’ symptoms could have been caused by a number of diseases and some of the symptoms were not consistent with Covid-19,” the report says.

Both the Trump and Biden administration ordered investigations of Covid’s origins, and intelligence agencies generated hundreds of pages of material. But

After three years of study, some senior U.S. officials have said that the spy agencies are unlikely to come to any satisfactory conclusion, in large measure because China has not cooperated with international inquiries and some officials in Beijing are not interested in digging deeper into the cause of the pandemic.

The new report is the result of a bipartisan law that ordered intelligence agencies to release a declassified version of what they know about whether Covid might have been created inside the Wuhan Institute of Virology and then accidentally escaped from the laboratory.

The report was released on a Friday evening, traditionally a time when administrations put out news they want buried or ignored. Conservatives had criticized the government for failing to meet a deadline of the beginning of the week, though few congressionally mandated reports are delivered precisely on time.

While Biden administration officials have said they have ordered investigations without favoring one theory over another, Republicans have harshly criticized how the White House and its intelligence agencies have investigated Covid’s origins.

“The lab leak is the only theory supported by science, intelligence and common sense,” John Ratcliffe, who served as the director of national intelligence in the Trump administration, said as the report was released Friday. “The Biden administration’s politicization of Covid origins is a disservice to the intelligence community.”