The National Institutes of Health is now examining whether experiments performed at Boston University should have triggered a federal review, the agency says, after scientists at the school tested strains they created of the virus combining the ancestral and Omicron variants.

Federal health authorities say they are looking into whether the scientists should have sought their permission before undertaking research that could lead to a “gain of function” in the virus gaining new or enhanced abilities, which can be “inherently risky.”

However, Boston University says its research followed “all required regulatory obligations and protocols” to safely experiment with the viruses.

“Before anything is done in the [National Emerging Infectious Diseases Laboratories], it goes through multiple layers of careful safety review and this is done through committees that are part of Boston University and also committees that are outside of, independent of, BU,” Robert Davey, a professor at Boston University’s National Emerging Infectious Diseases Laboratories, said in a statement.

The scientists were studying what role the Omicron variant’s highly-mutated spike protein might play in its generally milder severity compared to previous waves. 

Mice were exposed to “chimeric recombinant” versions created by the scientists, which carried the Omicron variant’s spike protein combined with the “backbone” of the original strain. Similar kinds of recombinant variants have evolved in the wild.

Their findings were released Friday as a preprint that has yet to be peer-reviewed. The NIH’s scrutiny was first reported by Stat News.

Though NIH money was not directly sought for the experiments, the agency is probing whether it may have still been subject to their grants policy

The experiments may have also required clearance first by the federal government’s rules governing experiments that could lead to a “gain of function” in the virus, the NIH said. This kind of research is supposed to be vetted by a group of experts convened by the federal government before it can be funded.

However, Boston University says it “did not have an obligation to disclose this research” to the NIH.

While funding from the NIH’s National Institute of Allergy and Infectious Diseases was acknowledged by the scientists in their paper, Boston University said the grants were only for “tools and platforms” used by the scientists .

“NIAID funding was acknowledged because it was used to help develop the tools and platforms that were used in this research; they did not fund this research directly. NIH funding was also acknowledged for a shared instrumentation grant that helped support the pathology studies,” Rachel Lapal Cavallario, a spokesperson for the university, said in a statement.

News of the NIH’s probe follows coverage of the Boston University research first in the Daily Mail. The university had denounced the tabloid for sensationalizing their research, with “false and inaccurate” reporting that took their findings out of context.

For example, those early reports on the findings highlighted that 80% of infected mice died after scientists infected the animals with the recombinant strain, while none died after being exposed to the Omicron variant.

The university points out that the original variant led to 100% of the mice dying, meaning that their recombinant virus was made effectively “less dangerous.”

If there were any signs the viruses they created for their experiments were “gaining function,” the scientists would have “immediately” stopped and reported their research, Lapal Cavallario said.

The research was also conducted in the university’s “BSL-3” lab. That is the second-highest tier of precautions scientists can take when studying viruses, short of those taken for studying the most dangerous pathogens “for which no vaccine or therapy is available.”

“We take our safety and security of how we handle pathogens seriously, and the virus does not leave the laboratory in which it’s being studied,” Ronald Corley, director of Boston University’s NEIDL, said in a statement.

The study’s lead author, Mohsan Saeed, and other experts have cited other research that have performed similar kinds of experiments without controversy. 

One study co-authored by Food and Drug Administration researchers over the summer also generated “chimeric viruses” with the Omicron and ancestral strains to test on mice.

That study’s authors and an FDA spokesperson did not return requests for comment.

The preprint comes amid scrutiny of the federal government’s policies governing research with enhanced potential pandemic pathogen (ePPP) research, which are in the midst of a review by an NIH working group.

“It is concerning that this research – like the research in Wuhan that may have caused the pandemic – was not identified by the funding agency as possible ePPP research,” Rutgers University Professor Richard Ebright wrote on Twitter.