COVID-19 Data Dispatch

Tag: BA.2.75

  • The Omicron subvariants start coming and they don’t stop coming

    The Omicron subvariants start coming and they don’t stop coming

    A veritable alphabet soup of subvariants. Chart from the CDC, data as of October 15.

    When the CDC updated its variant prevalence estimates this week, the agency added new versions of Omicron to the dashboard. In the U.S., COVID-19 cases are now driven by: BA.5, BA.4.6, BQ.1, BQ.1.1, BF.7, BA.2.75, and BA.2.75.2. And possibly more subvariants that we aren’t tracking yet.

    As evolutionary biology expert T. Ryan Gregory pointed out on Twitter recently, Omicron’s evolution is “off the chart.” 

    Or, to parody Smash Mouth: the Omicron variants start coming and they don’t stop coming and they don’t stop coming and they don’t stop coming…

    Let’s go over the veritable alphabet soup of variants we’re dealing with right now, as well as one newer variant identified in east Asia that experts are closely watching.

    BA.5, BA.4, BA.4.6

    BA.5 is currently the dominant Omicron lineage in the U.S., causing about two-thirds of new COVID-19 cases in the week ending October 15. Along with BA.4, BA.5 split off from the original Omicron lineage and was first identified by South African scientists over the summer.

    As these two subvariants spread around the world, it quickly became clear that they could spread faster than other versions of Omicron and reinfect people who’d previously gotten sick with those prior lineages. For more details, see this post from June. BA.5 later pulled out from BA.4 as the most competitive lineage.

    BA.4.6 evolved out of BA.4. It appears to have a small advantage over BA.5, but can’t really compete with the newer subvariants we’re seeing now; according to the CDC’s estimates, it’s been causing around 10% to 12% of new cases nationwide for the last few weeks (without much growth).

    BQ.1 and BQ.1.1

    BQ.1 and its descendant BQ.1.1 are the two newest subvariants to show up in the CDC’s prevalence estimates, both causing about 5.7% of new cases nationwide in the last week. They actually evolved out of BA.5: BQ.1 is shorthand for a much longer, more unwieldy variant name that nobody wants to type out on Twitter.

    In the U.S., BQ.1 and BQ.1.1 are starting to outcompete their parent lineage, BA.5. They’ve grown from causing less than 1% of new cases to over 10% of new cases in the last month. These subvariants are also now outcompeting other strains in the U.K. and other European countries.

    As CBS News’s Alexander Tin explains, health experts are concerned that COVID-19 treatments like monoclonal antibodies might work less well against BQ.1 and BQ.1.1. We don’t have clear data on this yet, but pharmaceutical companies will test out the newer variants in the weeks to come. The Omicron bivalent boosters, at least, are expected to continue working against this lineage.

    BF.7

    BF.7 is another offshoot of BA.5 (again, this is shorthand for a longer name). I dedicated a post to it in late September, and the subvariant’s position hasn’t changed significantly since then: it seems to be a bit more transmissible than BA.5, but not so much that it is quickly outcompeting the parent lineage. BF.7 caused about 5% of new cases nationwide in the last week.

    Similarly to BQ.1 and BQ.1.1, there are some concerns that COVID-19 treatments will be less effective against BF.7 than other versions of Omicron based on the subvariant’s spike protein mutations, but we do not have clinical data at this point.

    BA.2.75 and BA.2.75.2

    BA.2.75, as you might guess from the notation, evolved out of BA.2—the same original Omicron lineage that produced BA.2.12.1 and drove surges in places like New York City over the summer. It has also remained present at fairly low levels across the U.S. recently, causing just 1.3% of new cases in the last week, according to the CDC’s estimates.

    But BA.2.75 now has its own offshoot, called BA.2.75.2, that appears to be a bit more competitive. The CDC recently started splitting BA.2.75.2 out of its parent lineage in its prevalence estimates, showing that it’s growing a bit faster (from 0.4% to 1.4% in the last month). Of course, this growth rate pales in comparison to what we’re seeing from the BA.5 sublineages described above.

    XBB

    XBB is the latest international subvariant of concern, identified this week in several east Asian countries. It has spread particularly quickly in Singapore, as described in this article by David Axe at the Daily Beast.

    Like BA.2.75, XBB descended from Omicron BA.2—though it’s gone through more rounds of spike protein mutation; this is why experts are calling it XBB, rather than a long string attached to BA.2. Data so far indicate its growth advantage over BA.5 is similar to what we’re seeing from BQ.1.1. XBB has also raised concerns about treatment and vaccine efficacy, since the bivalent boosters were developed from BA.4 and BA.5. 

    The CDC and other health agencies have yet to identify XBB in the U.S.; experts are closely watching how this new subvariant might be able to compete with our current variations on BA.5.

    Overall takeaways

    Overall, both in the U.S. and around the world, we’re seeing a lot of competition between these subvariants. All of them have small growth advantages over BA.5—which is currently dominant in the U.S.—but none are so different that they’re completely pulling ahead.

    As I wrote last weekend, many experts are anticipating a surge this fall and winter, driven by both new subvariants and less-cautious beavior. We likely won’t see a huge spike at the level of last winter’s massive Omicron surge, but this season will still have plenty of infections (and reinfections).

    We will need more data on how all these newer variants respond to vaccines and treatments, especially the antiviral Paxlovid. But it’s at least promising that many of the circulating variants right now evolved from BA.5, against which our bivalent boosters were specifically designed. It’s a great time to get that booster!

    More variant data

  • National numbers, September 18

    National numbers, September 18

    Wastewater trends in the past couple of weeks are looking a bit messy, with a potential new surge in the Northeast and plateaus in other regions. Chart via Biobot, retrieved on September 18.

    In the past week (September 10 through 16), the U.S. reported about 420,000 new COVID-19 cases, according to the CDC. This amounts to:

    • An average of 60,000 new cases each day
    • 128 total new cases for every 100,000 Americans
    • 16% fewer new cases than last week (September 3-9)

    In the past week, the U.S. also reported about 31,000 new COVID-19 patients admitted to hospitals. This amounts to:

    • An average of 4,400 new admissions each day
    • 9.3 total admissions for every 100,000 Americans
    • 6% fewer new admissions than last week

    Additionally, the U.S. reported:

    • 2,500 new COVID-19 deaths (0.8 for every 100,000 people)
    • 85% of new cases are caused by Omicron BA.5; 10% by BA.4.6; 1% by BA.2.75 (as of September 17)
    • An average of 25,000 vaccinations per day (per Bloomberg)

    Officially-reported COVID-19 cases are still on the decline nationwide this week, as are newly hospitalized patients (a more reliable metric). About 4,400 people with COVID-19 were admitted to hospitals across the country, compared to over 6,000 a day in late July.

    These declines may be short-lived, as reopened schools and increased indoor gatherings contribute to new outbreaks this fall. Last week, I warned that Biobot’s wastewater data showed a slight uptick in coronavirus levels across the country; this week’s update shows a continued increase in the Northeast while other regions are in plateaus.

    Will the Northeast be the first region to experience a new surge again? It seems feasible, based on data from both Biobot and the CDC—though this region also has better wastewater surveillance coverage than other parts of the country, ABC News reporter Arielle Mitropoulos points out. Boston, one long-running wastewater surveillance location, is reporting high coronavirus concentrations at a level not observed since earlier in the summer.

    Nationwide, BA.5 continues to be the dominant variant, causing about 85% of new cases in the week ending September 17 per CDC estimates. But it’s facing competition from newer Omicron subvariants, including BA.4.6 (10% of new cases this week), BA.2.75 (1.3% of cases), and BF.7 (1.7% of cases). As of this week, the CDC is now reporting BA.2.75 and BF.7 separately rather than combining them with other lineages.

    BA.2.75, also called Centaurus, is a subvariant from BA.2 that evolved some additional mutations. BF.7 actually evolved from BA.5; its longer name is BA.5.2.1.X. There hasn’t been much reporting yet on BF.7, but it appears to be present in the Northeast—particularly in New England—at higher levels than in other regions. (Possibly another driver of a new surge in this area.)

    Overall, while COVID-19 spread in the U.S. is occurring less right now than it did earlier in the summer, the risk of encountering this virus is still pretty high across the country. According to the CDC’s “Community Transmission Level” guidance (pre-February), more than 90% of U.S. counties should require masks indoors.

    Instead, we have no masking requirements, increasingly-limited testing, and a booster shot campaign that many Americans do not even know is happening. Between 300 and 400 Americans still die of COVID-19 every day—a number that should be unacceptable—and I fear this number will only go up as we head into winter.

    more national numbers
  • BA.2.75 (Centaurus) is still a subvariant worth watching

    BA.2.75 (Centaurus) is still a subvariant worth watching

    The CDC’s variant prevalence estimates suggest that BA.2.75 has started to spread more in the U.S. in recent weeks.

    BA.2.75, a newer subvariant that evolved from BA.2, has been driving increased coronavirus transmission in some other countries recently. You might also see it referred to as “Centaurus” on social media. This lineage has yet to be identified in large numbers in the U.S., but I was inspired by a recent reader question to share what we’ve learned about it since my previous post in July.

    Scientists are concerned about BA.2.75 because it has several new mutations that are distinct from BA.2, most of those in the spike protein (where the virus binds to human cells). And some preliminary research, including recent studies in the Lancet Infectious Diseases and in the New England Journal of Medicine, have found that BA.2.75 is less susceptible to neutralizing antibodies from prior infections or treatments than past variants.

    This could mean people who previously caught BA.2 or other versions of Omicron could be susceptible to BA.2.75, reports Hannah Flynn in Medical News Today. Of course, more research and data are needed on the new variant. But BA.2.75 has been driving new surges in India, Nepal, and other countries—another signal that it’s worth watching.

    As I noted in today’s National Numbers post, the CDC is not yet reporting BA.2.75 prevalence estimates separately from other versions of BA.2. But it has reported an increase in BA.2 overall in recent weeks, from 0.6% of new cases in the week ending August 27 to 1% in the week ending September 10. This is probably BA.2.75, given that older versions of BA.2 haven’t been competitive in the U.S. for a few months.

    Helix, a COVID-19 testing company that works with the CDC and other agencies on variant surveillance, is tracking BA.2.75 separately from BA.2 on its dashboard. According to Helix’s data, original BA.2 has stayed at very low prevalence in recent weeks while BA.2.75 has risen to 1% of cases sequenced.

    It’s currently unclear—as it was in July—to what extent BA.2.75 might be able to compete with BA.5 or BA.4.6, which are the main subvariants of concern spreading across the U.S. right now. But if BA.2.75 does become dominant, it will be helpful that the newly-authorized booster shots include genetic material from the original, Wuhan variant, not just BA.4 and BA.5.

    More variant reporting

  • BA.2.75 is the latest Omicron subvariant of concern

    BA.2.75 is the latest Omicron subvariant of concern

    BA.2.75 has further mutations which could allow the variant to bypass past immunity. Figure via scientist Ulrich Elling on Twitter.

    As if BA.4 and BA.5 aren’t already enough to worry about: some COVID-19 experts are sounding the alarm about BA.2.75, a new version of Omicron that evolved out of BA.2.

    This subvariant was first identified in India in late May, and has now been reported in the U.K., Germany, and several other countries, according to the World Health Organization. Scientists are concerned because it has new spike protein mutations that could heighten its ability to bypass immunity from past infections or vaccinations—including, potentially, from BA.4 or BA.5.

    At least three BA.2.75 cases have been reported in the U.S. so far, according to a Friday press release from the surveillance company Helix. Two of these cases were on the West Coast, in Washington and California. These cases are currently lumped in with other versions of BA.2 on the CDC dashboard.

    The information on BA.2.75 is fairly preliminary at this point; the WHO is monitoring it as an additional lineage of Omicron, not a separate variant of concern, and watching for new data. It’s unclear how competitive it might be with BA.5, now dominant in the U.S., but is worth keeping an eye on. As Dr. Katelyn Jetelina points out in a recent issue of Your Local Epidemiologist, the spread of BA.2.75 could further complicate fall booster shot plans. 

    More variant reporting