While it may be a new year, the same problem remains: COVID-19. This time, though, it is a subvariant of the COVID-19 Omicron variant, known as XBB.1.5, that is the dominant strain in parts of the United States.
The rise of the COVID-19 Omicron subvariant XBB.1.5 is the product of a potent mix of mutations that make it easier to spread broadly, including among those who have been previously infected or vaccinated. That means there are higher chances for reinfection or breakthrough infections.
Here are some questions patients might have about the XBB.1.5 COVID-19 subvariant, along with the answers that physicians should be ready to share.
What is the XBB.1.5 subvariant?
Since the COVID-19 Omicron variant became the world’s dominant strain, it has mutated into different subvariants. First it was BA.1, then it was the BA.5 Omicron subvariant. It eventually mutated into BQ.1 and BQ.1.1.
Now there is XBB.1.5—nicknamed the Kraken—which derived from the BA.2 Omicron subvariant. It is part of the XBB family of variants that emerged a few months ago and caught virologists’ attention because it contains more mutations to evade immunity than other variants seen so far. The XBB.1.5 subvariant has a mutation that is believed to help the virus bind to cells, becoming more transmissible.
Why is XBB.1.5 nicknamed the Kraken?
“It is definitely an unusual name. ‘Kraken’ is the name of a mythological sea monster and XBB was given this name by a Canadian biology professor who has been trying to demystify COVID variants by giving them mythological names,” Sandra Adamson Fryhofer, MD, an Atlanta general internist and chair of the AMA Board of Trustees, said on an episode of “AMA Update.”
“Now, it is a little easier to say than the XBB.1.5. But the name sounds scary,” Dr. Fryhofer said. “But just because it's been given the nickname of a sea monster doesn't necessarily mean it's more dangerous. Of course, we need hard data to make that determination.”
Is XBB.1.5 more transmissible?
COVID-19 cases in the U.S. caused by XBB.1.5 have gone from 1% to more than 40% rather quickly. In fact, scientists are reporting that this subvariant “appears to bind more tightly to cells in the human body than the predecessors,” said Andrea Garcia, vice president of science, medicine and public health at the AMA.
“It also seems to be more resistant than earlier variants to immune system antibodies,” Garcia said, noting that “we’re likely going to continue to see that increase in cases.”
Where is XBB.1.5 spreading?
In December, the XBB.1.5 subvariant caused less than 10% of COVID-19 cases in the U.S. During the first week of January, though, it was reported that XBB.1.5 accounted for about 40% of cases. But because of the holidays, there were delays in reporting the data from states, so it was just an estimate.
Now the Centers for Disease Control and Prevention (CDC) has a clearer picture of impact of the XBB.1.5 subvariant. As of Jan. 13, the CDC now estimates that XBB.1.5 accounts for about 43% of cases, making it the most dominant strain in the country. BQ.1.1 is now the second most dominant strain at about 29% of COVID-19 cases. But that could change quickly.
At the moment, XBB.1.5 is the most dominant strain of COVID-19 in the Northeast, making up more than 80% of cases in New York and New Jersey. It has also been detected in at least 28 other countries but is not a dominant strain.
What are the symptoms of XBB.1.5?
Symptoms with XBB.1.5 appear to be similar to the earlier Omicron subvariants. Those can range from typical cold symptoms such as cough and congestion to shortness of breath and low oxygen levels that require emergency medical attention.
But as XBB.1.5 continues to spread, the signs and symptoms of COVID-19 may seem different than what was seen earlier in the pandemic with Alpha or Delta variants. Symptoms such as the temporary loss of taste and smell can still happen in some instances, but it has become less common with the Omicron variant and subvariants.
Other symptoms may include fever, chills, fatigue, muscle or body aches, sore throat, nausea or vomiting and diarrhea. Symptoms can last between five to seven days but vary from person to person.
Is XBB.1.5 infection more severe than other COVID-19 variants?
“The experts generally believe that the symptoms of COVID have become less severe over time,” Garcia explained. “That could be because they tend to remain in the upper respiratory tract and don't affect the lungs as much as earlier variants.”
“But it could also be because people in the U.S. have some level of immunity from vaccines or prior infection,” she said, noting that “many people who are infected now are reporting those mild symptoms like cough, congestion and a headache that could be confused with symptoms of the cold or flu.”
“Although XBB.1.5 is one of the most antibody-resistant variants, it doesn't seem to carry any mutation known to be associated with a potential change in severity. However, studies of disease severity are now ongoing,” said Dr. Fryhofer who also serves as the AMA’s liaison to the CDC’s Advisory Committee on Immunization Practices (ACIP) and is a member of ACIP’s COVID-19 Vaccine Work Group.
Should I still be testing for COVID-19?
Many people who are infected with SARS-CoV-2 have been reporting mild symptoms such as cough, congestion and headaches. These symptoms can often be confused with the cold or flu. But if you notice any of these symptoms, it is important to test for COVID-19. This can differentiate between COVID-19, the cold and flu as well as help discern what treatments to follow.
Does XBB.1.5 evade immunity from vaccination or previous infection?
While researchers are still compiling data, it appears that if you have been infected with an earlier Omicron variant, you may still be susceptible to reinfection with XBB.1.5. This is because the XBB.1.5 subvariant is more immune-evasive.
On top of that, a person’s immune response naturally decreases over time following infection. The same can be said for vaccination. While it offers some protection, over time that immune response begins to wane.
Subscribe to AMA Update
Get videos with expert opinions from the AMA on the most important health care topics affecting physicians, residents, medical students and patients—delivered to your inbox.
Am I still at risk for long COVID with the XBB.1.5 subvariant?
The short answer is yes. With each COVID-19 variant, the risk of long COVID or post-COVID conditions remains. This can include a wide range of ongoing health problems that can last for weeks, months or longer.
While long COVID has been reported more often in people who have had severe illness, it can impact anyone who has been infected with SARS-CoV-2, even people who had mild illness or no symptoms. Although, new research has shown that for those with mild illness, long COVID symptoms clear after a year.
Will the COVID-19 bivalent vaccine still offer protection from XBB.1.5?
Getting vaccinated and staying up to date on COVID-19 boosters remains the best form of protection from serious illness, hospitalization and death. The updated COVID-19 bivalent booster offers added protection against the variants that are currently circulating because it is half original strain, half Omicron BA. 4 and BA.5 subvariants.
While there is still confusion surrounding the need for bivalent boosters, a new study out of Israel—that is preprint and not yet peer-reviewed—examined the effectiveness in preventing severe outcomes in those 65 or older. The study showed an 81% reduction in hospitalizations in people 65 or older who had received the bivalent booster compared to those who had received two doses of a COVID-19 vaccine, but not the updated dose.
“The bottom line is that if you haven’t gotten your bivalent booster, there’s time, but you’ve got to get it soon or you’re at risk for hospitalization,” AMA member Peter Hotez, MD, PhD, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children’s Hospital Center for Vaccine Development in Houston, said in a Houston Chronicle interview. “With the new XBB1.5 subvariant, the goalposts have moved. That’s the reality of it.”
“Early data from November, pre-XBB.1.5, from the CDC shows that people who get the bivalent booster have 18.6 times reduction of risk of being hospitalized,” Dr. Hotez said. “It’s not quite as good as that for XBB.1.5, but it should have benefits there too.”
Are COVID-19 treatments still effective for infections caused by XBB.1.5?
Yes, treatments are still expected to be effective at treating COVID-19 infections caused by XBB.1.5. These treatments can help reduce the severity of illness. Oral antivirals such as Paxlovid and molnupiravir are expected to be effective against XBB.1.5 because they don’t function by boosting antibodies, which this strain appears to be able to evade. Instead, these oral antivirals work by hindering the virus’ ability to replicate itself.
However, the Food and Drug Administration (FDA) has indicated that they do not anticipate that Evusheld will neutralize XBB.1.5. This means it may not provide protection against developing COVID-19 in individuals who have received the drug for pre-exposure prophylaxis. The FDA is currently awaiting additional data to verify that Evusheld is not active against XBB.1.5.
How can I protect myself from the XBB.1.5 subvariant?
This advice may sound like a broken record, but the best way to protect yourself from XBB.1.5 subvariant of Omicron is to get vaccinated and stay up to date on COVID-19 vaccines. Beyond vaccination, it is important to assess your risk level and keep that top of mind. If you will be around others in an indoor setting, consider wearing a mask. But not just any mask will do. It is important to wear an N95 or KN95 mask for the best protection.
XBB.1.5 is “probably also spreading faster because most people are no longer wearing masks,” said Dr. Fryhofer, noting “this might be a good time to start wearing a mask again if you're not already. … I will say I've seen a lot more people wearing masks in the airport.”
On top of vaccination and wearing a mask, avoid poorly ventilated spaces and maintain physical distancing from others. And if you feel sick, stay home and get tested to determine the best course of action.
Table of Contents
- What is the XBB.1.5 subvariant?
- Why is XBB.1.5 nicknamed the Kraken?
- Is XBB.1.5 more transmissible?
- Where is XBB.1.5 spreading?
- What are the symptoms of XBB.1.5?
- Is XBB.1.5 infection more severe than other COVID-19 variants?
- Should I still be testing for COVID-19?
- Does XBB.1.5 evade immunity from vaccination or previous infection?
- Am I still at risk for long COVID with the XBB.1.5 subvariant?
- Will the COVID-19 bivalent vaccine still offer protection from XBB.1.5?
- Are COVID-19 treatments still effective for infections caused by XBB.1.5?
- How can I protect myself from the XBB.1.5 subvariant?
