A new COVID-19 variant, which is increasing in number while the BA.5 omicron subvariant begins to decline, is one of several variants currently being tracked by the Centers for Disease Control and Prevention as it heads into the fall and winter while experts are on the lookout for a mutation that could cause another surge in the pandemic.
While the Omicron subvariant BA.5 has been the dominant COVID strain in the United States for several months, there are at least four other subvariants gaining ground in recent weeks.
According to the latest estimates released Tuesday by the CDC, subvariant BA.5 still accounts for 84.8% of COVID cases in the United States. It’s slightly higher in the Midwest, accounting for 86.8% of cases.
This subvariant, which has been the dominant COVID strain in the US since early July, reached nearly 90% of cases at one point, but has been slowly declining as at least four other omicron types circulate in the population.
One of these strains, subvariant BA.4.6, 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 gaining 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 US and responsible for an estimated 1.8% of cases, but two other subvariants are now being followed by the CDC as they keep a close eye on the development of new strains ahead of 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.18.104.22.168, but scientists have instead abbreviated it to BF.7 in reporting documents.
Scientists continue to keep a close eye on this subvariant, responsible for 1.7% of cases, as it has now surpassed another Omicron sublineage, BA.2.75, in terms of cases at this time. In the Midwest, BF.7 accounts for an even larger percentage of cases, currently at 2%.
According to Fortune magazine, Belgium is currently seeing an increase in BF.7 cases, as are Denmark, Germany and France.
“This BF.7 is the first time we’ve declared this,” the Chicago Department of Health Commissioner said during a Facebook Live Tuesday, acknowledging the postponement of variant tracking. “It’s only 2% of the time… It’s an offshoot of BA.5, but it has a different mutation, you know, in the tip [protein].”
Scientists are monitoring whether the BF.7 subvariant behaves differently than BA.5, but all Omicron strains share similar characteristics, showing an increased ability to evade pre-existing immunity from previous infections and an increased ability to evade one Avoid vaccine-mediated immunity.
“BA.5 [is] still most cases. We usually see one come out and another come in. It’s a little unusual to see this BA.2.75 grow back after it shrunk and the BF.7 – we’re watching,” said Arwady.
It is currently unknown how effective the new bivalent COVID vaccines, 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 subsequent variants in the fall and winter.
“One of the reasons we’re really excited about this updated COVID vaccine is that unlike last year, we have a match again,” Arwady said Tuesday. “So this updated vaccine – just like in the beginning those first vaccines were very protective, we didn’t see much breakthrough… now again, although it’s a good match, I would expect there to be significantly more protection against infection as well.”
Until now, COVID-19 vaccines have targeted the original strain of coronavirus, even as entirely different mutants have emerged. The new US boosters are combo or “bivalent” shots. They contain half the original vaccine recipe and half protection against the latest Omicron versions called BA.4 and BA.5, believed to be the most contagious yet.
The combo aims to increase cross protection against multiple variants.
The FDA’s move streamlines the recipe of shots made by Pfizer and rival Moderna, which have already saved millions of lives. The hope is that the modified boosters will dampen another winter surge.
“We’re just back to 99 percent agreement between what we’re seeing in the spread and the protection that the vaccine can provide,” Arwady said. “And my concern is that we’re going to miss the window. People will not choose to get this updated booster and we will miss the opportunity on an individual level but more importantly on a societal level to be in the best shape into the winter. I don’t know if we’ll see a new variant pop up like omicron did last year. I certainly hope not, but the more people can compare to what’s out there now, the more protection it will be better.”
Here is a list of variants currently being tracked by the CDC and how common they are in the US or Midwest:
BA.5 – US: 84.8%, Midwest: 86.8%
BA.4 – US: 1.8%, Midwest: 1.7%
BA.4.6 – US: 10.3%, Midwest: 7.9%
BA.2.75 – US: 1.3%, Midwest: 1.6%
BF.7 – US: 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%