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.
According to the latest figures from the Centers for Disease Control and Prevention, BA.5 is responsible for an estimated 81.3% of COVID cases in the United States, down from 83.2% a week ago.
The variant has been the dominant strain of COVID in the U.S. since July 2, according to CDC data, but its stranglehold on that top spot may soon be challenged by two other omicron sublineages.
The BA.5 subvariant rose to prominence at the same time as the BA.4 subvariant, but it’s a descendant of BA.4 that is growing most quickly in the U.S. According to CDC estimates, BA.4.6 is responsible for 12.8% of cases this week, up from just under 12% a week ago.
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The BF.7 subvariant, a descendant of BA.5, is responsible for 3.4%, according to CDC estimates.
Like other evolutions of the COVID virus, new spike proteins on both BA.4.6 and BF.7 are helping the virus to better evade both natural immunity conferred from previous iterations of omicron and immunity gained by vaccination, even with new boosters on the market.
It remains unclear whether those new bivalent boosters, which are specially-formulated to help fight back against severe illness from omicron, will protect against infection in general, with studies still underway even as Americans begin to get the shots.
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Overall, cases are still on the way down in the U.S., as are deaths and hospitalizations. According to the CDC, no Illinois county is currently at a “high” transmission rate of the virus, with most falling in the “low” or “medium” categories.
