The omicron subvariants BQ, XBB pose a serious threat to boosters

The injection of Evusheld, a new COVID treatment that people can take before they become symptomatic, in Chicago on Friday, February 2. 4, 2022.

Chris Sweda | Tribune News Service | Getty Images

Omicron subvariants that have become dominant in recent months pose a serious threat to the effectiveness of new boosters, make antibody treatments ineffective and could lead to increased infections, according to a new study innovative

The omicron subvariants BQ.1, BQ.1.1, XBB and XBB.1 are the most immune evasive variants of Covid-19 to date, according to scientists affiliated with Columbia University and the University of Michigan. These variants, together, are currently causing 72% of new infections in the US, according to data from the Centers for Disease Control and Prevention.

The scientists, in a study published online Tuesday in the peer-reviewed journal Cell, found that these subvariants are “barely susceptible to neutralization” by vaccines, including the new omicron boosters. The immune response of vaccinated individuals who had breakthrough infections with previous omicron variants was also weaker against the subvariants.

“Together, our findings indicate that the BQ and XBB subvariants pose serious threats to current COVID-19 vaccines, inactivate all licensed antibodies, and may have gained dominance in the population due to their advantage in evading antibodies,” the scientists wrote.

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Although these subvariants are more likely to cause breakthrough infections, the vaccines have been shown to remain effective in preventing hospitalization and severe disease from omicron, the scientists wrote.

The study looked at blood samples from people who received three or four injections of the original vaccines, from those who received the new omicron boosters after three injections of the original vaccines, and from individuals vaccinated with the vaccines originals that also had breakthrough BA.2 or BA.5 subvariant infections.

For people who received the omicron boosters, infection-blocking antibodies were 24-fold lower against BQ.1, 41-fold lower against BQ.1.1, 66-fold lower against XBB, and 85-fold lower against XBB.1 compared to its performance against the ancestral strain. . which emerged in Wuhan, China in 2019.

However, people who received the omicron boosters had slightly higher levels of antibodies against all of these subvariants compared with people who received three or four shots of the original vaccines, the study found.

People who were vaccinated and had breakthrough infections had the highest antibody levels of any group in the study, although neutralization was also much lower against the subvariants than the ancestral strain.

Subvariants have evolved from previous versions of omicron dramatically. According to the study, BQ.1.1, for example, is as different from omicron BA.5 as the latter subvariant is from the ancestral strain of Covid.

“Therefore, it is alarming that these newly emerged subvariants may further compromise the efficacy of current COVID-19 vaccines and lead to an increase in breakthrough infections as well as reinfections,” the scientists wrote.

XBB.1, however, presents the biggest challenge. According to the study, it is about 49 times more resistant to antibody neutralization than the BA.5 subvariant. XBB.1, fortunately, currently causes no more than 1% of infections in the US, according to CDC data.

BQ.1.1 and BQ.1 account for 37% and 31% of new infections respectively, while XBB is causing 4.7% of new infections, according to CDC data.

Ineffective antibodies

The key antibody drugs, Evusheld and bebtelovimab, were “completely inactive” against the new subvariants, according to the study. These antibodies are mainly used by people with weak immune systems.

Evusheld is an antibody cocktail used to prevent Covid in people with weak immune systems who do not respond strongly to vaccines. Bebtelovimab is used to prevent Covid from progressing to severe disease in organ transplant patients and others who cannot take other treatments.

“This poses a serious problem for millions of immunocompromised individuals who do not respond robustly to COVID-19 vaccines,” the scientists wrote. “The urgent need to develop active monoclonal antibodies for clinical use is obvious.”

The Food and Drug Administration has already withdrawn its authorization of bebtelovimab nationwide because it is no longer effective against the dominant omicron variants in the US. Evusheld remains authorized as the only option for pre-exposure prophylaxis.

New Covid infections rose by about 50% to 459,000 in the week ending December. 7, according to CDC data. Deaths from Covid rose by 61% to almost 3,000 in the same week. According to the data, hospital admissions have stabilized at an average of 4,700 a day after rising in November.

The White House Chief Medical Advisor, Dr. Anthony Fauci, at a news conference last month, said that US health officials hope there is enough immunity in the population against vaccination, infection or both to prevent the massive increase in infections and hospitalizations that the united states suffered last winter when omicron arrived.

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