The BA.5 omicron subvariant, which has been the dominant strain of COVID-19 in the United States for more than three months, is still responsible for 4-in-5 cases of the virus, but its grip is beginning to loosen as two other variants gain steam.
Months after it sparked a nationwide surge, the omicron subvariant BA.5 continues to remain the most dominant COVID-19 strain in the U.S. Its hold, however, appears to be waning, based on recent data from the Centers for Disease Control and Prevention.
BA.5 accounted for 79.2% of all U.S. COVID cases for the week of Oct. 2-8, marking a more than 2% decrease from one week prior, when it was responsible for 81.5% of cases.
Both the BA.4.6 and BF.7 subvariants have gained traction in recent weeks, with BA.4.6 increasing from 9.2% of all COVID cases to 13.6% in just over one month's span. BF.7 appears to be following a similar route, as it rose from 0.8% of all U.S. cases on Sept. 3 to 4.6% by Oct. 8.
As was the case with other evolutions of the COVID virus, new spike proteins on both subvariants are helping the virus to better evade both natural immunity conferred from previous iterations of omicron and immunity gained by vaccination, even with the availability of new boosters.
It remains unclear whether those new bivalent boosters, which are specially-targeted to help fight back against severe illness from omicron, will protect against infection in general, with studies still underway even as Americans get the shots.
Dr. Michelle Barron, an infectious disease expert with the University of Colorado Health, says there's no need to worry about the latest subvariants - at least yet.
"“They’re like tropical storms," she said in an article dated Sept. 30. "They’re way out in the ocean right now. We’re aware of what they have the potential to do, but they may never gain enough strength to hit land or even become a named storm."
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New subvariants could potentially cause more challenges in the coming months, as the weather gets colder and people spend time indoors.
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Earlier this week, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and White House chief medical advisor, discussed the possibility of another COVID variant emerging in the winter, rendering existing immunity less effective.
Dr. Allison Arwady, commissioner of the Chicago Department of Public Health, shared similar concerns during a Facebook question-and-answer session earlier this week. With both influenza and COVID surges possible in the winter months, Arwady is encouraging people to get the bivalent booster as soon as possible.
A new variant, on top of both surges, if they occur, could lead to an increased strain on hospital resources.
"The hope is that it will not be a crazy new variant," the doctor explained. "If we can get people vaccinated right now with the updated COVID vaccine that protects against the omicron variants that...we're seeing, we will be in a much better place heading into the fall and winter."
Not much is known about the latest subvariants, but some have especially shared concerns about the BF.7 variant. According to early reports, it could be highly infectious, Barron said.
“It has some novel sequences that make it more transmissible," she explained. "The other concern is the potential for more severity. If it’s like the love child between delta and omicron (variants), that would be bad. But all of our information is still very premature."
Regardless of which subvariant becomes most dominant, health officials assert the same strategies recommended to prevent COVID-19 infections early on in the pandemic are still effective. They include wearing a mask, washing hands frequently and testing if you believe you've contracted COVID.
