Experts Keeping Close Eye on BA.2.86 Variant

With more than 30 mutations, BA.2.86 is capturing the attention of public health experts around the world, including the CDC, which issued a risk assessment on the new COVID variant on Wednesday.

Though just nine BA.2.86 sequences — including 2 in the U.S. — have been reported to date, its differences have been enough to set it apart for further study.

CDC’s assessment noted that this new variant “may be more capable of causing infection” in those who have previously had COVID or who have received COVID vaccines.

“This one does have a large number of mutations that are obviously a concern,” Aubree Gordon, PhD, MPH, associate professor of epidemiology at the University of Michigan School of Public Health,” told MedPage Today. “It may be better at evading prior immunity, both from vaccination and infection. And so that’s really the big concern.”

However, “Just because it has more mutations … that doesn’t mean it will actually take off,” Gordon cautioned.

Indeed, one of the cases of BA.2.86 in the U.S. was detected by a University of Michigan lab “as part of routine sequencing to identify new variants,” the university said in an announcement.

The affected patient was not hospitalized and is an older adult who experienced mild symptoms, the university added, citing a statement from leadership at the Michigan Department of Health and Human Services.

Public health experts will be looking at whether there are more severe cases and more hospitalizations, and whether BA.2.86 is beating out other variants, Gordon said.

And there will be laboratory-based work, such as neutralization testing using serum from individuals who have been vaccinated, infected, or a combination of both to determine how well the new variant evades immunity, she added.

BA.2.86 has yet to appear on CDC’s weekly variant tracking update; however, the agency is monitoring it. CDC noted that “one analysis of mutations suggests the difference may be as large as or greater than that between BA.2 and XBB.1.5, which circulated nearly a year apart.”

“However, virus samples are not yet broadly available for more reliable laboratory testing of antibodies, and it is too soon to know the real-world impacts on immunity,” the agency added. “Nearly all the U.S. population has antibodies to SARS-CoV-2 from vaccination, previous infection, or both, and it is likely that these antibodies will continue to provide some protection against severe disease from this variant.”

Initially, there were less than a handful of sequenced cases, but now a few more “trickled in,” and there is “reason to continue to monitor it,” Shishi Luo, PhD, head of infectious diseases at the population genomics company Helix, told MedPage Today.

Beyond tracking the number of cases, determining the clinical characteristics in patients will be extremely important, Luo said.

“The key to the public health response in the U.S. is being able to connect sequencing data with clinical patient data,” Luo said.

Though the WHO has yet to name BA.2.86 a variant of concern (VOC), or even variant of interest (VOI), it has designated it a variant under monitoring (VUM).

Gordon acknowledged that having a new variant with so many mutations start appearing as the U.S. heads into fall “can be a little bit more of a concerning time.”

Though Gordon expects a fall or winter surge of COVID, she said it remains to be seen whether it will be as a result of BA.2.86 or another variant or variants.

At the same time, “We’re also in a very different stage than we were a few years ago for encountering new variants,” Gordon said. “Because if you look back to 2021 or 2020, population-level immunity was very different.”