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A medical worker administers tests at a COVID-19 testing site in Brooklyn on April 18, 2022, in New York City. Spencer Platt/Getty Images
  • The BA.2.12.1 is spreading rapidly and overtaking the BA.2 Omicron subvariant.
  • Little is known about the new subvariant, however, it appears to be highly transmissible, much like its ancestors.
  • Medical News Today spoke to 5 experts to understand more about the subvariant.

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BA.2.12.1, a new descendant of the BA.2 subvariant of Omicron, is spreading quickly. Between April 16 and 23, 2022, the percentage of COVID-19 cases caused by the subvariant increased from 19.6% to 28.7% in the U.S.

The new subvariant has notably increased in New York, where it accounted for 58.1% of cases on April 23, up from 0.2% in late February.

To understand more about this emerging subvariant, MNT spoke to five experts on topics ranging from what we know so far about the variant itself to vaccine efficacy.

“BA.2.12.1 is a descendant of the BA.2 virus,” Dr. Angela Branche, the co-principle investigator of the University of Rochester Medical Center Vaccine Treatment and Evaluation Unit, told MNT.

“BA.2 was the primary strain associated with the most recent wave of Omicron infections this past winter peaking in in January 2022,” she said.

Dr. Branche also elaborated on the new subvariant’s transmissibility in relation to its ancestor BA.2, also referred to as “stealth Omicron.”

“BA.2 was known to have 53 mutations compared to the original virus, 29 of which were in the spike protein. This led to an increased ability of the virus to transmit from person to person. The BA.2.12.1 subvariant also has this increased ability to replicate and transmit from person to person and […] seems poised to become the dominant strain in the U.S. over the next few weeks,” she explained.

Why exactly BA.2.12.1 may be more transmissible remains unknown. Dr. David Cutler, family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA told MNT there were too many factors that could be contributing to its spread at the moment.

“It is unclear exactly why cases are rising. Is it because of BA.2.12.1? Is it because people are not wearing masks? Is it because immunity from prior vaccines is waning? These are just some of the unknowns raised by any new variant,” he said.

Dr. Fady Youssef, a board certified pulmonologist, internist, and critical care specialist at MemorialCare Long Beach Medical Center in Long Beach, CA, said information regarding BA2.12.1 was still very premature.

“Thus far, it does not seem to cause more severe disease than Omicron. However, we need further data before we can definitively say,” he told MNT.

Dr. Cutler agreed that BA.2.12.1 might not cause more severe disease as there has not been a rise in hospitalizations alongside increasing cases of the subvariant.

When asked how the new BA.2.12.1 subvariant may compare to other variants of Omicron, Prof. Elizabeta Mukaetova-Ladinska, professor in psychiatry of old age at the University of Leicester, the U.K., said its clinical symptoms may be similar to Omicron subvariant BA.2.

In most people, she said, this would mean flu-like symptoms that affect the upper respiratory tract symptoms but not the lungs. She added that these mild effects might arise from a hybrid immunity from vaccination and prior infection.

Dr. Dana Hawkinson, medical director of the Infection Control and Prevention program at The University of Kansas Medical Center, told MNT that the BA2.12.1 subvariant might, nevertheless, be more infectious and transmissible than the original BA.1 Omicron variant.

“Early data also suggests BA.2.12.1 has increased ability to infect the lower respiratory tract (lungs) compared to BA.1 Omicron, which could be one factor in its overall risk of severe disease,” he added.

In a recent study, researchers found that even after three mRNA vaccine doses, effectiveness against Omicron-related hospitalization dropped from 85% to 55% after three months.

The researchers concluded that additional booster vaccines might thus be necessary to remain protected against infections with Omicron subvariants.

While it is unclear how many vaccines one may need—and how often—to remain significantly protected from COVID-19, all five of the experts MNT spoke to agreed that getting vaccinated is still better than being unvaccinated to be protected against SARS-CoV-2 infections.

Dr. Hawkinson pointed out that there was “good evidence” to suggest that those who have had at least three doses of the mRNA COVID-19 vaccines ( two primary doses and a booster) still produce antibodies against BA.2.12.1.

He highlighted that the spike protein mutations that allow the virus to evade antibody responses occur less frequently. Thus, he said, T cell responses from vaccines should still offer protection.

Prof. Mukaetova-Ladinska agreed that experience with past mutations suggests that COVID-19 vaccines should still offer protection against severe disease.

“Currently, SARS-COV-2 should be a cause for concern, particularly if you are unvaccinated,” said Dr. Hawkinson.

If you have been vaccinated and remain up-to-date with the recommended vaccine doses, or have been vaccinated and infected or vice versa, you should be fairly well protected and have significantly less risk of hospitalization, severe disease, and death than those who have not been vaccinated,” he explained.

Dr. Cutler added that we should not be complacent about COVID-19 and should continue to observe public health safety measures. He said this was crucial as the more the virus mutates, the more likely it is to develop resistance to current vaccines and treatments.

“Omicron BA.1 was susceptible to the sotrovimab monoclonal antibody, while BA.2 was not. And while BA.2.12.1 seems to be responding to the new bebtelovimab monoclonal antibody, there is no guarantee that future subvariants will remain so,” he added.

“While the new subvariants will perpetuate the pandemic-causing infection in susceptible people, there is great hope for preventing serious impact using proven strategies,” Dr. Cutler told MNT.

“High-quality masks prevent infection. Maintaining distancing and improving ventilation reduce infection risk. And vaccines still are the best-proven strategy for preventing serious illness or death from any new COVID-19 variants.”
— Dr. David Cutler