Since the pandemic's onset more than two years ago, sudden increases in COVID-19 cases have been driven by the emergence of new variants, including delta and omicron. Currently, a more contagious omicron subvariant, called BA.5, accounts for most new U.S. cases, however a separate, newer subvariant is garnering attention.
Known as BA.2.75, the subvariant may be able to evade immunity from vaccines and prior infection, scientists assert. The strain includes multiple mutations in the gene encoding for the spike protein of the virus, which allow the virus to bind to the host cell receptor more efficiently, Dr. Matthew Binnicker, director of the Clinical Virology Laboratory at Mayo Clinic, explained in an article.
Detected in India in May, the strain appears to be spreading quicker than other subvariants there and is under monitoring by both the World Health Organization as well as the Centers for Disease Control and Prevention. Cases have surfaced in at least a dozen countries, including the U.S., where numbers remain extremely low.
A total of 13 cases have been confirmed in the U.S., with three of those in Illinois, said Dr. Allison Arwady, commissioner of the Chicago Department of Public Health.
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At this point, it doesn't appear the strain will lead to another major COVID wave in the U.S., but the possibility remains.
"...We are keeping our eye on it," Arwady said. "We do a good job of testing and looking forward here, which is one of the reasons why we may find it [BA.2.75]."
BA.2.75 is more effectively spread from person to person, according to Binnicker, who explained there's no solid data to show it causes more severe disease compared to other subvariants. However, as more people are infected, the chances that the virus infects someone who is more susceptible rises.
"...Those who have an immunocompromised condition could still end up with severe disease and be hospitalized," he explained ."It is a concern whenever a virus can infect people at a higher rate because the chances that the virus will infect an individual who is highly susceptible to worse outcomes then increases."
The threat of the BA.2.75 variant in India underscores the importance of global vaccination, Dr. Sabrina Assoumou, a doctor at Boston Medical Center, told NBC Boston.
"We're not going to be able to get over this pandemic if we don't make sure that everyone, everywhere, is safe," she stated.
India's population has a different immunity than the U.S., multiple Boston doctors said, because different vaccines were given at various times and different variants circulated at various times. Those variables result in fluctuating levels of infection-induced immunity.
"We cannot assume that what's happening there will happen here, and yet we do have to prepare for surges. We are always now preparing for surges," Dr. Shira Doron, of Tufts Medical Center, said. "Variants will emerge that evade immunity from the vaccine and prior infection, and we can't ever quite know exactly what they're going to do to our case rates until we get there."
As the school year approaches and new variants, including BA.2.75, lead to additional cases, monitoring the number of infections will be crucial.
"There definitely is concern that as we move into the fall and winter months of 2022, and then into 2023, that the new strains of the virus, including BA.27.5, will increase as kids go back to school," stated Binnicker. "They're going to be interacting, and there's going to be increased rate of transmission of viruses, including COVID 19."