A new report from a World Health Organization team Tuesday identified substantial gaps in the story of how the coronavirus spread to humans, yet concluded that one possible scenario — a laboratory accident in China — was “extremely unlikely.”

Not so fast, says Richard Ebright.

A longtime microbiologist at Rutgers University, Ebright joined 25 other scientists earlier this month in calling for a thorough, independent investigation of where the virus came from.

The WHO team collaborated with Chinese officials, as negotiated in advance due to the politically sensitive nature of the inquiry, and had limited access to lab records and other raw data. As a result, it remains impossible to determine whether a lab or some “natural” source was the starting point of the COVID-19 pandemic, said Ebright, a professor of chemistry and chemical biology at the university’s Piscataway campus.

“There is no way to rule in or rule out either scenario,” he said.

More than a year after the first cases of a mysterious pneumonia-like illness were identified in Wuhan, few would dispute that the question of its origin suffers from a lack of clear answers. Even WHO Director-General Tedros Adhanom Ghebreyesus called the report from his agency’s handpicked team “an important beginning,” but said its members were hampered by limited information.

“In my discussions with the team, they expressed the difficulties they encountered in accessing raw data,” he said Tuesday in an address to member nations. “I expect future collaborative studies to include more timely and comprehensive data sharing.

Ebright is among a small group of infectious-disease experts who have publicly questioned the official narrative since the beginning.

In January 2020, Chinese authorities said the virus appeared to have jumped to humans at a live-animal market in Wuhan, in the province of Hubei. But Ebright immediately wondered if a different source was possible: the nearby Wuhan Institute of Virology, where the topics of study included other coronaviruses.

Evidence soon emerged that the market probably was not the source after all. Several of the first people to become ill had not been to the market before developing symptoms, nor did they have any apparent connection to the location, epidemiologists found. Weeks after Ebright and others voiced skepticism, Chinese authorities agreed the market theory was wrong.

Many scientists still think that some sort of natural origin is to blame. If not the Wuhan market, then another one, or perhaps a wildlife farm that supplied such markets with animals. In the new report, the team of scientists assembled by WHO proposed that the most likely scenario was that the virus was transmitted from a horseshoe bat to some intermediate animal and then to humans.

Maybe, said Ebright, who was editor of the Journal of Molecular Biology for 16 years. But without sufficient evidence, he said, it is premature to discount any possibility.

What’s clear is that the genetic code for the coronavirus is very similar to those of other coronaviruses found in bats. But just how this virus got from bats to humans is an open question.

Lab accidents are rare, but not unheard of, Ebright said. He noted that a different coronavirus, which causes a similar illness called SARS, originated in animals in 2002 but later infected Chinese scientists who were studying it in a lab. Why couldn’t that have happened this time?

“The only way that one can distinguish between these hypotheses, short of a confession, is to have access to lab facilities and lab records and lab samples and medical records and serological samples and personnel to interview privately,” Ebright said.

The authors of the WHO report were able to visit the virology lab in Wuhan, but only for a few hours, team members told the Washington Post. In addition to judging that a lab accident was unlikely, they dismissed out of hand another lab-related possibility: that scientists had deliberately engineered the coronavirus. Ebright does not think that scenario is likely, but said it was premature to reject it without a thorough investigation.

Asked why many U.S. scientists were so quick to discount the lab-origin theory, he said one reason might be that it had been espoused by Trump administration officials. But in other countries, the topic is not “politicized,” he said. In their March 4 letter calling for an independent investigation, most of the scientists joining Ebright were from abroad.

An important note: Though bats are eaten by some people in Asian countries, it is inappropriate to blame that food choice for COVID or any other infectious disease, Ebright said. Other viruses that infect humans come from animals commonly eaten worldwide. The flu originated in birds, for instance, and measles is thought to have descended from a cow virus.

And anyway, it’s not the eating of animals that tends to pose a threat, but the handling of them when they are live.

“It’s not the eating habits of a people,” he said.

Nailing down the origin story of the coronavirus would not help in curbing the pandemic, and it is not about assigning blame, he said. The reason for investigating the topic is to learn how the world can prevent it from happening again.

But unless investigators get unfettered access to study records, collect samples, and ask questions, he doubts much progress will be made.

“We’re at a stopping point,” the microbiologist said, “where this may end up being something that is unsolved for a very long time.”