Is XBB.1.5 the Most Transmissible Variant?

Omicron XBB.1.5, also called the “Kraken” variant, is currently responsible for nearly 50 percent of new cases this month, the U.S. Centers for Disease Control and Prevention (CDC) estimates. The World Health Organization (WHO) recently warned that XBB.1.5 could start a worldwide escalation in COVID-19 infections.

However, it also noted that growth advantage estimates are only from the United States, so the organization rated its confidence in their escalation assessment as “low,” while warning the variant could more easily evade protective measures.

“Along with BQ.1 variants, XBB variants are the most antibody-resistant variants to date,” the WHO said in a statement (pdf).

Steep Rise in Cases

By end of December 2022, XBB.1.5 accounted for just under 12 percent of infections, but by the first week of January, that number has risen to 43 percent, according to CDC data.

In a Jan. 4, Twitter post, White House COVID-19 coordinator Ashish Jha called this a “stunning increase.”

Jha said that while XBB.1.5 could be more contagious, but it’s still unclear whether it causes more severe disease.

A new, not yet peer-reviewed study reveals a likely reason why this variant is spreading so fast.

The researchers found XBB.1.5 binds more tightly to human ACE receptors compared to other circulating variants. This may be due to a rarely seen amino-acid change, called F486P, in the spike protein.

“Over time, the SARS-Cov-2 ancestral strain has been replaced by variants which are more easily transmissible and immune-evasive,” Dr. Miriam Smith, chief of infectious disease at Long Island Jewish Forest Hills in Queens, told The Epoch Times.

“Most recently, the XBB.1.5 subvariant arose through genetic recombination between other Omicron variants,” she continued.

The prefix “X” in the variant’s name is how virologists label a pathogen that evolved through genetic recombination between two or more subvariants.

Most Transmissible COVID-19 Variant Yet

Last week, the New York City Department of Health announced that Omicron XBB.1.5 accounted for 73 percent of all sequenced COVID-19 cases in the nation’s most populated city.

“It may be more likely to infect people who have been vaccinated or previously had COVID-19 compared to prior variants,” the agency cautioned.

According to the most current CDC data, the Northeastern United States is most affected by XBB.1.5, with around 80 percent of cases in the region being caused by the variant.

Dr. Eric Cioè-Peña, director of Global Health for Northwell Health, explained that XBB.1.5 is different in similar ways that previous variants differed from what was circulating when they emerged.

This means it has many mutations that help it dodge existing immunity and is very infectious.

“It takes less time with someone who’s sick, and less quantity of viral exposure to get infected,” said Cioè-Peña.

But does this mean it’s an entirely new variant—something novel that COVID-19 vaccines may not work against? Cioè-Peña said it is, and it isn’t.

“COVID vaccines are less effective in preventing infection,” he said. “Until now, it seems like they are still effective in protecting you once you are infected, from needing oxygen, hospitalization, or [from dying].”

However, it’s still too early to tell if the vaccine will continue to provide protection from XBB.1.5.

Cioè-Peña thinks the most recent booster that targets Omicron subvariants is more effective than the original vaccine.

The New Bivalent Vaccine

In December 2022, the CDC reported that the bivalent vaccines had demonstrated protection against hospitalization and mortality versus the unvaccinated population or recipients who have been vaccinated and boosted—especially for those 65 years of age or older.

“This protection has been shown to hold for the XBB.1.5 subvariant as well,” said Smith.

The elderly population, patients with major underlying co-morbid conditions that put them at risk for severe disease, and patients with underlying immunosuppressive disorders should receive the bivalent vaccine, advised Smith.

However, she emphasized that while not yet clearly known, “the durability of the protective effect from these vaccines will likely decrease after six months.”

But the shots are controversial.

Some studies indicate the bivalent shot might not be more effective at preventing COVID-19 infections than the original shots. One study was co-authored by Dr. David Ho, a professor of microbiology and immunology at Columbia University, and another by Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center.

As the virus mutates over time, is it possible that available vaccines won’t offer any protection against a new variant? Could we, at some point, be facing a new and deadlier phase of the pandemic?

“That’s always a risk,” said Cioè-Peña, “but the more we get ‘used’ to COVID, immunity-wise, the less chance [there is] of that occurring.”

He added that there’s always a risk that there could be a major shift, “almost so it’s a completely new coronavirus,” and that could be a game changer for the pandemic.

Views expressed in this article are the opinions of the author and do not necessarily reflect the views of The Epoch Times. Epoch Health welcomes professional discussion and friendly debate. To submit an opinion piece, please follow these guidelines and submit through our form here.

George Citroner reports on health and medicine, covering topics that include cancer, infectious diseases, and neurodegenerative conditions. He was awarded the Media Orthopaedic Reporting Excellence (MORE) award in 2020 for a story on osteoporosis risk in men.
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