Over the past few months, most COVID-19 cases in the U.S. have been Omicron subvariants BA.4 and BA.5.

But now, a group of new COVID subvariants is becoming more common, and one of them is getting a lot of attention. It is called XBB or Gryphon, and there is a chance that it could take over everything else.

William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine, says that XBB is getting a lot of attention because it spreads quickly and seems to be able to get around the immunity that people have built up from having COVID-19 before or getting the vaccine. Still, Dr. Schaffner says that “it’s early days and we have a lot to learn.”

What we know about XBB and why doctors are monitoring it.

What is the XBB COVID Variant?

Thomas Russo, M.D., professor and head of infectious disease at the University at Buffalo in New York, says that XBB is one of the “new class” of Omicron variants that are spreading quickly right now. He says that’s true for BQ.1.1, BQ.1, BQ.1.3, BA.2.3.20, and XBB.

Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security, notes that “XBB is a hybrid version of two strains of the BA.2 form of Omicron.” He continues, “It’s spreading effectively in Singapore right now.”

According to Singapore’s Ministry of Health, the variant was discovered for the first time in India in August 2022 and has since been found in more than 17 nations, including Australia, Bangladesh, Denmark, India, Japan, and the United States.

According to a pre-print study by researchers in China, XBB is expected to have the strongest capacity to evade antibody defenses of these recently revealed COVID variants. According to this study, the new Omicron strains, specifically XBB, “are the most antibody-evasive strain tested, far exceeding BA.5 and approaching SARS-CoV-1 level.” If you’re not aware with it, SARS-CoV-1 is the coronavirus strain that causes SARS, a respiratory virus that can result in serious disease.

Meaning that, in contrast to earlier strains of COVID-19, the vaccine and having previously had COVID-19 are not believed to provide as much protection against XBB. According to the pre-print study, anti-XBB medications like Evusheld and bebtelovimab may also not be particularly effective.

“These variants are evolving to evade protection,” claims Dr. Russo. Despite being “imperfect against preventing infection,” the bivalent booster is “likely going to be protective against severe disease” in XBB patients, according to Dr. Russo.

But don’t freak out. It’s crucial to understand that vaccine protection is not all or nothing when it comes to evasion, according to Dr. Adalja. “Vaccine protection against what matters most—severe disease—remains intact even with immune-evasive variants.”

XBB Variant Symptoms

So far, the symptoms of XBB seem to be the same as the general signs of COVID-19. The Centers for Disease Control and Prevention (CDC) lists the following as examples:

  •  Fever or chills
  • · Cough
  • · Shortness of breath or difficulty breathing
  • · Fatigue
  • · Muscle or body aches
  • · Headache
  • · New loss of taste or smell
  • · Sore throat
  • · Congestion or runny nose
  • · Nausea or vomiting
  • · Diarrhea

How Contagious is the XBB Subvariant?

People think that XBB is very infectious, just like other strains of Omicron. The Ministry of Health in Singapore says that 54% of COVID-19 cases in the country now involve the version, which is up from 22% the week before.

The Ministry of Health in Singapore says that XBB is “at least as contagious as currently circulating variants,” but that there is no evidence that XBB makes sickness worse.

When will the XBB Subvariant Peak?

Right now, there is a lot we don’t know about XBB. Even though it has been found in the U.S., CDC data shows that BA.5 and BA.4.6 are still the most common types.

Dr. Adalja says that other types are also spreading at the same time, and it’s not clear which will replace BA.4.6 and BA.5 in the U.S., if they do. He says, “It’s likely to spread a little bit in the U.S., but it’s not clear if it or a related variant like BQ.1.1 will take over.”

Dr. Schaffner says that there is “some concern” about the rise of XBB and other similar variants. “It’s important to keep an eye on the next few weeks,” he says.


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