COVID-19 Omicron Variant XBB.1.5 More Dominant, Makes Up 40 Percent of New Cases in US: CDC

Nothing currently suggests it is more severe, CDC official says

Pedestrians cross the street on Chicago's Michigan Avenue as they brave the freezing weather ahead of the Christmas holiday on Dec. 23, 2022. Kamil Krzaczynski/AFP via Getty Images

The COVID-19 Omicron XBB.1.5 subvariant nearly doubled in prevalence over the past week, data from the U.S. Centers for Disease Control and Prevention (CDC) showed on Friday, with it now comprising over 40 percent of new cases in the United States.

Specifically, for the week ending Dec. 31, CDC data puts the Omicron XBB.1.5 subvariant as making up 40.5 percent of the total new COVID-19 cases in the country. That figure was 21.7 percent in the week ending Dec. 24.

Meanwhile, subvariants BQ.1 and BQ.1.1 are now at 26.9 percent and 18.3 percent of total new U.S. cases, respectively. Last week, BQ.1.1 was 33.2 percent and BQ.1 was at 24.1 percent of new cases.

The XBB.1.5 subvariant appeared in the United States around late November and has roughly doubled in prevalence every week since, according to CDC data. It accounts for the majority of current COVID-19 cases in the U.S. northeast, at around 75 percent of cases in the New York tri-state area and New England.

Dr. Barbara Mahon, the director of the CDC’s proposed Coronavirus and Other Respiratory Viruses Division, told CBS News that it is projected to be the dominant variant in the U.S. northeast and will increase in prevalence in other regions of the country. However, she said there is “no suggestion at this point that XBB.1.5 is more severe.”

Meanwhile, the BQ.1.1 Omicron subvariant still makes up most cases in the country’s south and west.

XBB ‘Highly Transmissible’: Japanese Researchers

XBB.1.5 descended from the XBB subvariant. The latter was first identified in India in August and quickly became dominant in the country. XBB has also been responsible for the increase in COVID-19 cases in parts of Asia, including Singapore.

In a recent interview with Reuters, Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota, said that “probably the worst variant that the world is facing right now is actually XBB.” He added that seven of the 10 U.S. states where cases and hospitalizations are rising are in the northeast, concurrent with an increase of XBB cases there.

XBB is a recombinant of two subvariants that descended from the Omicron BA.2 subvariant. This means that genetic data from two versions of the virus that descended from BA.2 that had infected a person at the same time, combined during the viral replication process to form the new XBB subvariant.

Japanese researchers said in a paper posted to the preprint server bioRxiv on Dec. 27 that their findings suggest XBB is the “first documented SARS-CoV-2 variant increasing its fitness through recombination rather than single mutations.” The researchers also said their results suggest that XBB is “highly transmissible” and highly resistant to the immunity that was induced by people having had breakthrough infections of the previous Omicron subvariants.

XBB.1.5 Spreading Faster

Yunlong Richard Cao, a Chinese scientist and assistant professor at Peking University, noted that XBB.1.5 has an additional change compared to XBB called the S486P mutation, which gives it a “greatly enhanced” ability to bind to cells through a key receptor called ACE2, or angiotensin-converting enzyme 2.

“The fact that XBB.1.5 showed a much superior growth advantage than XBB.1 suggests that hACE2 [human ACE2] binding affinity does play a heavy role in SARS-CoV-2 spreading. XBB.1 truly suffered from low-hACE2 binding, despite XBB.1’s highest immune evasion capability,” he wrote on Twitter.

Researchers from Columbia University, in a paper published Dec. 13 in the journal Cell, noted that the newly emerged subvariants raise concerns that they may “further compromise the efficacy of current COVID-19 vaccines and monoclonal antibody (mAb) therapeutics.”

“We now report findings that indicate that such concerns are, sadly, justified, especially so for the XBB and XBB.1 subvariants,” they wrote. Part of their findings showed that the new subvariants—Omicron BQ.1, BQ.1.1, XBB, and XBB.1—were able to evade being neutralized by antibodies “from vaccinated individuals with or without prior infection, including persons recently boosted with the new bivalent [booster vaccine].”

“[I]t is alarming that these newly emerged subvariants could further compromise the efficacy of current COVID-19 vaccines and result in a surge of breakthrough infections as well as re-infections,” the scientists wrote. “However, it is important to emphasize that although infections may now be more likely, COVID-19 vaccines have been shown to remain effective at preventing hospitalization and severe disease even against Omicron as well as possibly reducing the risk of [long COVID].”

In the United States, vaccine manufacturers are immune from liability for any adverse reactions unless there’s “willful misconduct” involved.

Health care providers who administer COVID-19 vaccines are required by law to report any serious adverse effects or vaccination administration errors to the Vaccine Adverse Event Reporting System (VAERS), hosted by the U.S. Department of Health and Human Services.

The federal government has a countermeasures program that can compensate eligible persons who suffer serious injury from approved vaccines. But the burden of proof has proven a challenging process.

Other than COVID-19 vaccines, people have taken preventative measures to help boost their immune system and prepared home-based early treatment protocols. A number of protocols have been recommended by various doctors and groups, including the Front Line COVID-19 Critical Care Alliance (FLCCC) and the World Council for Health.

Update: This article has been updated with added information.