Chicago’s top doctor pointed to what could be the start of a shift in COVID variants circulating in the United States and the Midwest this week.
“We’re starting to see a bit of a change here,” Chicago Department of Public Health Commissioner Dr. Allison Arwady said during a Facebook Live on Tuesday, specifically highlighting the changes in BA.2.75 and a new variant BF.7.
While the omicron BA.5 subvariant has been the dominant strain of COVID in the United States for several months, there are at least four other subvariants that are beginning to gain traction.
According to the latest estimates released by the CDC on Tuesday, the BA.5 subvariant is still responsible for 84.8% of COVID cases in the United States. In the Midwest, it is slightly higher, accounting for 86.8% of cases.
This subvariant, which has been the dominant strain of COVID in the United States since early July, peaked at nearly 90% of cases at one point, but slowly began to decline as at least four other types of omicron are beginning to circulate in the population.
One of these strains, the BA.4.6 subvariant, is now responsible for more than 10% of COVID cases in the United States for the first time. The subvariant, which has been circulating since at least early June, now accounts for 10.3% of cases and is slowly beginning to gain momentum as its parent strain BA.4 continues to decline. In the Midwest, BA.4.6 accounts for 7.9% of cases.
The BA.4 subvariant is still the third most common in the United States, responsible for about 1.8% of cases, but two other subvariants are currently being tracked by the CDC as they keep a cautious eye on development. new strains before the fall and winter months.
The BF.7 subvariant is actually a subline of BA.5, according to the CDC. Its official name is BA.188.8.131.52, but scientists have instead shortened it to BF.7 in reporting documents.
Scientists continue to closely monitor this subvariant, responsible for 1.7% of cases, as it has now overtaken another omicron subline, BA.2.75, in terms of cases at present. In the Midwest, BF.7 accounts for an even larger percentage of cases, currently standing at 2%.
According to Fortune magazine, Belgium is currently experiencing an increase in BF.7 cases, as are Denmark, Germany and France.
“This BF.7, this is the first time we’ve called this,” Arwady said. “It’s only 2% of cases… It’s an offshoot of BA.5, but there’s another mutation, you know, in the peak [protein].”
Scientists are monitoring whether the BF.7 subvariant behaves differently from BA.5, but all omicron strains share similar characteristics, showing an increased ability to circumvent pre-existing immunity from previous infections and an increased ability to avoid vaccine-mediated immunity.
“BA.5 [is] still most cases. Usually we see that one spell comes out of the competition and a new one comes in. It’s a bit unusual to see this BA.2.75 growing again after it’s shrunk and the BF.7 – we’re watching,” Arwady said.
It is not currently known how effective the new bivalent COVID vaccines, which have been specifically formulated to target omicron subvariants, will be against BF.7. Arwady said the new booster shots remain important to increase protection against the omicron variant and later variants as we approach fall and winter.
“One of the reasons we’re really excited about this updated COVID vaccine is that unlike about last year, we’re back to having a game,” Arwady said on Tuesday. “So this updated vaccine – kind of like in the beginning those early vaccines were highly protective, we weren’t seeing a lot of breakthrough…even now even though it’s a good game, I would expect that there is much more protection against infection as well.”
Until now, COVID-19 vaccines have targeted the original coronavirus strain, although wildly different mutants have emerged. The new American boosters are combined or “bivalent” shots. They contain half the original vaccine recipe and half the protection against the latest versions of omicron, called BA.4 and BA.5, which are considered the most contagious to date.
The combination aims to increase cross-protection against multiple variants.
The FDA decision changes the recipe for injections made by Pfizer and rival Moderna that have already saved millions of lives. The hope is that the modified boosters will mitigate yet another winter surge.
“We’re back right now to a 99% match between what we see spreading and the protection the vaccine can provide,” Arwady said. “And I’m afraid we’re missing the window. People won’t choose to get this updated booster and we’ll miss the opportunity on an individual level, but more importantly on a societal level to be in the best possible shape. as winter approaches I don’t know if we’re going to see a new variant emerge like omicron did last year I certainly hope not but the more people there will be that can be matched to what is circulating now, the better the protection will be.”
Here is a list of variants currently tracked by the CDC and their prevalence in the United States or the Midwest:
BA.5 – United States: 84.8%, Midwest: 86.8%
BA.4 – United States: 1.8%, Midwest: 1.7%
BA.4.6- United States: 10.3%, Midwest: 7.9%
BA.2.75 – United States: 1.3%, Midwest: 1.6%
BF.7 – United States: 1.7%, Midwest: 2%
BA.2.12.1 – 0%
BA.2 – 0%
BA.1.1.529 – 0%
BA.1.1 – 0%
BA.1.617.12 – 0%