Two subvariants of omicron continued to gain ground this week, while the BA.5 subvariant remains the dominant strain of COVID-19 in the U.S. even as case numbers start to dip.
According to the latest estimates from the Centers for Disease Control and Prevention, the BA.5 subvariant is now responsible for 79.2% of cases in the U.S., down from 81.3% a week ago.
BA.5 has been the dominant strain of COVID in the U.S. since July 2, and at its peak was responsible for an estimated 90% of cases across the country.
As BA.5 cases have continued to dip downward, two other strains have seen their case numbers continue to rise. The BA.4.6 subvariant, a descendant of the BA.4 strain that rose to prominence along with BA.5 earlier this summer, is now responsible for 13.6% of cases, making it the second-most prevalent in the United States.
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The BF.7 subvariant, a descendant of BA.5, is now at 4.6% of cases in the U.S., up from 3.4% just a week ago.
The BF.7 subvariant is responsible for an estimated 5% of cases in the Midwest, and 5.6% cases in New York, according to CDC data.
While both BA.4.6 and BF.7 have specific mutations in their spike proteins that make it more easily transmissible than previous strains, it is not known at this time whether the subvariants are able to more easily move around immunity conveyed by previous COVID infection or COVID vaccination, according to the CDC.
New bivalent COVID vaccines, specifically formulated to offer protection against omicron strains of the virus, are now in wide circulation across the U.S., but studies are still being conducted to determine their efficacy against newer-strains of COVID.
These new vaccines come as the state of Illinois sees COVID cases continuing to dip, with most of the state currently at a “low transmission” level of the virus, per the CDC.
On average, just over 1,500 new COVID cases per day are being reported by the Illinois Department of Public Health, the lowest rate of transmission the state has seen since earlier this spring.