(CNN) The US intelligence community reached an inconclusive assessment about the origin of the Covid-19 virus following a 90-day investigation ordered by President Joe Biden, according to an unclassified summary of the probe released publicly on Friday.
The intelligence community is still divided about which of the two theories -- that the virus came from a lab leak or that it jumped from animal to human naturally -- is likely to be correct, the intelligence community said. There is consensus among the intelligence agencies that the two prevailing theories are plausible, according to the summary released by the Office of the Director of National Intelligence.
"All agencies assess that two hypotheses are plausible: natural exposure to an infected animal and laboratory-associated incident," the intelligence community wrote.
The unclassified report, two-page report, was released Friday by the intelligence community after Biden had asked intelligence agencies to "redouble" their efforts to determine how the Covid-19 pandemic began. Biden, who tasked them with declassifying as much of the report as possible, was briefed on the investigation earlier this week.
"While this review has concluded, our efforts to understand the origins of this pandemic will not rest," Biden said in a statement after the summary was released Friday. "We will do everything we can to trace the roots of this outbreak that has caused so much pain and death around the world, so that we can take every necessary precaution to prevent it from happening again."
In the statement, Biden criticized China for not being more transparent in helping the investigation, and the intelligence community said China's cooperation would likely be needed to reach a more definitive conclusion.
"Critical information about the origins of this pandemic exists in the People's Republic of China, yet from the beginning, government officials in China have worked to prevent international investigators and members of the global public health community from accessing it," Biden said.
While the investigation did not reach a conclusive assessment on the origin of the virus, it did knock down some theories. The intelligence community judged, for instance, that Covid-19 was not developed as a biological weapon, as some Republicans had suggested last year. The report says most agencies assessed with low confidence that it's unlikely Covid-19 was genetically engineered, either.
Four intelligence community agencies and the National Intelligence Council assessed, with low confidence, that Covid was likely caused by natural exposure to an animal, the summary says. One agency assessed with moderate confidence, however, that the first human infection most likely was the result of a lab-associated incident that "probably involving experimentation, animal handling, or sampling by the Wuhan Institute."
And three agencies said they were unable to coalesce around either explanation without additional information.
One of the agencies that did not take a firm position one way or the other was the CIA, according to a source who was briefed on the contents of the classified report.
The intelligence report says the virus probably emerged and infected humans through an initial small-scale exposure that occurred no later than November 2019.
But the summary says that the intelligence community would need more information from the early days of the pandemic to provide "a more definitive explanation for the origin of Covid-19."
"The IC -- and the global scientific community -- lacks clinical samples or a complete understanding of epidemiological data from the earliest Covid-19 cases," the intelligence community wrote.
China's unwillingness to cooperate hampered the intelligence community's ability to get answers on the origins of the virus. "China's cooperation most likely would be needed to reach a conclusive assessment of the origins of Covid-19," the intelligence community said. "Beijing, however, continues to hinder the global investigation, resist sharing information and blame(s) other countries, including the United States."
While the report does lay blame on China, it says Chinese officials "did not have foreknowledge of the virus before the initial outbreak."
Earlier this month, CNN reported intelligence agencies were poring through a trove of genetic data drawn from virus samples at the lab in Wuhan that some officials believe could have been the source of the outbreak.
Officials told CNN this week that the intelligence agencies were switching sides on which theory was more likely as recently as last week.
Biden launched the review into the origins of Covid-19 earlier this year amid growing calls for a deep dive after a US intelligence report found several researchers at China's Wuhan Institute of Virology fell ill in November 2019 and had to be hospitalized.
Last month, a bipartisan group of lawmakers said they want Biden to continue investigating the virus' origins even after the 90-day review is completed.
The window to find an answer to the pandemic's origins could be fading, however. A team of experts commissioned by the World Health Organization said Wednesday that the opportunity to find out where the pandemic began is disappearing as people's immune responses fade away and any evidence in the bodies of animals vanishes.
This story has been updated with additional reporting.