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At least half a dozen versions of the virus are competing to become the next dominant strain in the United States, but they are part of the same family tree. “They are all offspring of omicron,” said Dr. Albert Ko, a physician and public health researcher at the Yale School of Public Health. Though each subvariant has slightly different mutations, none of them seem to be creating significant waves just yet, the way the delta and omicron variants did when they first appeared, Ko said.
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According to the Centers for Disease Control and Prevention, the BA.5 subvariant, which powered the summertime COVID-19 surge, still causes just under half of infections across the country. But two other subvariants are growing rapidly and are expected to outcompete BA.5 very soon: BQ.1 and BQ.1.1.
As of last Friday, BQ.1 accounted for 14% of COVID-19 infections in the United States, while BQ.1.1 accounted for 13.1%. Another variant, called BA.4.6, has also gained some ground since August. It now accounts for 9.6% of cases.
BF.7, BA.5.2.6, BA.2.75 and a number of other variants are also jockeying for position in the United States, while another variant called XBB has made headlines for its role in a COVID-19 case surge in Singapore. Some reports have gone so far as to call XBB the “nightmare variant,” even though the number of cases and hospital admissions associated with it was already significantly down by Oct. 29.
The case counts and locations of each subvariant are important mainly for close observers of the pandemic, who are trying to track how well the subvariants evade immune protections, how much they will circulate in a community and how severe they can be for those infected.
How worried should I be about these new subvariants?
The evolution of new coronavirus variants is nothing new. “We’ve dealt with this before, with influenza, for example,” Ko said. “Viruses and pathogens are constantly trying to adapt and escape the immune pressure that we pose to them.”
With new, more immune-evasive subvariants, healthy adults are more likely to be infected even after vaccination or after a previous infection with a different variant. Indeed, a few preprint studies indicate that prior infection or vaccination might not produce antibodies that protect strongly against the new subvariants in lab experiments.
But other parts of the immune system can come to our defense, said Dr. Otto Yang, an infectious disease physician and immunology researcher at the University of California, Los Angeles David Geffen School of Medicine.
The mutations defining these new variants are clustered in and around a key area for antibody interactions, but the overall spike sequence is not really changed enough to affect T cells that recognize any part of the sequence, and they are what prevent severe illness,” Yang said. “People who are up to date on their vaccines and who get treatment early with Paxlovid or with remdesivir are going to do fine for the most part.” (Paxlovid is an oral antiviral medication, and remdesivir is an injectable antiviral.)
Most experts are not concerned with the possibility of new subvariants causing mild illness. “If we see that deaths are reduced and if serious illness and hospitalizations are reduced, even if people do get infected, that’s still a big success,” said Michael Osterholm, a public health researcher and the director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
Immune evasion is a bigger concern for people who are immunocompromised or who don’t mount a strong immune response to vaccines. That includes people who have had stem cell or solid organ transplants, people receiving cancer treatments, people with autoimmune diseases and people who need immune-suppressive medication for various medical conditions, said Dr. Alpana Waghmare, an infectious disease expert at Fred Hutchinson Cancer Center.
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