Meet XBB.1.5, the new COVID subvariant that defies immunity, infects more efficiently

INQUIRER FILE PHOTOS/JEROME CRISTOBAL

MANILA, Philippines—New year, new COVID-19 variant? Scientists and health experts have recently expressed concern over the new variant of SARS-CoV-2, the virus that causes COVID-19, which is quickly spreading across the United States.

On December 16 last year, amid increasing hospitalizations in New York, scientist JP Weiland noted a “new variant to watch.” According to him, the XBB.1.5 variant has started taking off in the state where it appears to have evolved.

By December 31, the US Centers for Disease Control and Prevention (CDC) announced that cases of the XBB.1.5 variant had doubled, accounting for 40.5 percent of total COVID-19 infections across the US.

Dr. Eric Topol, a genomics expert and director of the Scripps Research Translational Institute in La Jolla, California, also noted that the new variant has already outcompeted all variants—including previously dominant BQ.1.1 and BQ.1 variants.

Wow. XBB.1.5 more than doubled across the United States in 1 week, now ~40%, out-competing all variants pic.twitter.com/PeE8P7eAeH

— Eric Topol (@EricTopol) December 30, 2022

In this article, INQUIRER.net will detail what scientists and health experts know so far about the new XBB.1.5 variant, which is believed to be responsible for increasing infections and hospitalizations across the US.

XBB.1.5: What we know so far

The XBB.1.5, according to Canadian evolutionary and genome biologist T. Ryan Gregory, is the fifth descendant of the Omicron XBB.1 variant, which stemmed from the XBB variant—a recombinant variant between two BA.2 lineages (BA.2.10.11 and BA.2.75.3.1.1.1).

The US CDC and Gregory said that it is not yet known whether the XBB.1.5 can cause more severe illness. It is also not yet sure if the new Omicron variant can invade different tissues or if it is more likely to lead to long COVID.

However, the US CDC and several scientists and health experts noted the new variant’s immune evasiveness.

“We do know that XBB.1.5 has a concerning combination of both very high immune escape (it can infect despite vaccination or prior infection) and high ACE2 binding (it is good at attaching to and entering host cells),” Gregory said in a Twitter post on January 3.

The XBB.1.5’s very high immune evasion and high ACE2 binding properties, according to Gregory, is a problematic combination.

The US CDC had already added the new XBB.1.5 variant on its list of Variants of Concern (VOC). However, the World Health Organization (WHO) has yet to add it to its VOCs and Omicron sub-variants under monitoring.

Where did it emerge, where is it now?

In a series of Twitter posts, Topol, Weiland, and Gregory pointed out that the new XBB.1.5 variant evolved from the Omicron XBB or XBB.1 variant in the US, specifically in New York, where hospitalizations have been rising.

So far, outside the US, the new variant has reached South Korea, India, and the United Kingdom.

READ: New Omicron subvariant XBB.1.5 detected in South Korea

New ‘super variant’?

Epidemiologist and health economist Dr. Eric Feigl-Ding called the XBB.1.5 a “super variant” and the “next big one,” citing the following reasons:

• the XBB.1.5 is among the most immunity-evasive “escape variants” to date
• it is one of the “best variants” for invading human cells via ACE2
• it spreads faster than previous XBB or BQ COVDI-19 variants
• it causes the rise of hospitalizations wherever it is dominant

Feigl-Ding explained that across four US states where XBB.1.5 is the dominant variant—New York, Connecticut, Massachusetts, and New Jersey—hospitalizations had been steadily increasing.

📝Recap why #XBB15 (storming 🇺🇸&🇬🇧) is a super variant:

📍among most immunity-evasive ‘escape variants’ to date

📍one of the best variants for invading human cells via ACE2.

📍Spreads much faster than old XBB or BQ

📍Causes ⬆️hospitalizations wherever dominant (NY CT MA NJ)🧵 pic.twitter.com/n655wzvEHw

— Eric Feigl-Ding (@DrEricDing) December 31, 2022

However, Gregory noted that hospitalizations due to the new Omicron variant would not be as bad as the worst wave early in the pandemic.

GRAPHIC: Ed Lustan

“Hospital capacity is nowhere near what it was due to burnout and illness,” he said in a separate Twitter post.

PH still XBB.1.5 free, but…

The Department of Health (DOH) on January 3 said that there had been no reported case of XBB.1.5 in the Philippines yet.

“The DOH assures the public that the government continues to implement COVID-19 surveillance and monitoring activities and is confident in detecting potential variants that may enter the country,” DOH said in a statement.

However, the DOH reminded the public to continue observing minimum public health standards—which include physical distancing, hand hygiene, cough etiquette, and wearing of masks—as new COVID-19 variants continue to emerge and re-emerge.

“What’s important is we continue to employ our layers of protection, such as sanitation, masking, distancing, vaccination, and boosters, as well as good ventilation, to keep cases manageable and prevent virus transmission,” the health department said.

READ: PH still free of XBB 1.5 COVID-19 subvariants – DOH

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