So, Exactly How Worried Should We Be About the XBB.1.5 Variant? An Infectious Disease Expert Explains
Plus, how protected you are if you're vaccinated.
Last month, the XBB.1.5 variant was responsible for less than 10% of COVID infections in the U.S. Today, those numbers have spiked and this new variant has caused 27.6% of cases.
With the emergence of this new variant and COVID numbers on the rise, we’re all wondering more about how it's spreading, if vaccination will protect us and how to stay safe. Here's everything we know so far.
What Is the XBB.1.5 Variant?
XBB.1.5 variant is the next dominant strain of COVID-19. It is rising at a rapid rate in the United States and is replacing the previous dominant variants from the BA.5 lineage.
The XBB variants are derived from the recombination of two strains of the BA.2 lineage of omicron (an earlier dominant strain), Dr. Vineet Menachery, MD, assistant professor in the department of microbiology and immunology at the University of Texas Medical Branch, explains.
Get ready for some scientific jargon: XBB.1.5 has many of the same spike mutations and immune evasion as other omicron strains, according to Dr. Menachery. However, a mutation at position 486 in XBB.1.5 spike is predicted to improve binding to the human ACE2 receptor and is thought to be driving XBB.1.5 emergence through increased transmission.
“XBB.1.5, nicknamed ‘Kraken’ is thought to have arisen in India and spread to the U.S. in late 2022,” says Dr. William Li, MD, doctor, researcher, Angiogenesis Foundation President/Founder and author of Eat To Beat Disease. “In early December it represented only 2% of infection but by early January it had increased by 10-fold to 28%. In the Northeast, XBB.1.5 accounts for almost 80% of cases of COVID.”
What Do We Know About the XBB.1.5 Variant So Far?
The rapid increase in XBB.1.5 in patients suggests that the F486S mutation is increasing transmission and is very contagious. This mutation is unusual and was not observed previously because it requires two adjacent mutations in the spike, Dr. Menachery states.
While likely increasing transmission capacity, XBB.1.5 has not shown any increase in disease or severity. It is also predicted to have similar immune evasion of vaccine and infection-produced immunity as other omicron strains.
However, the increase in transmissibility will increase total case numbers and a new wave should be expected in the coming months, Dr. Menachery adds. With a higher number of cases, we will also see increases in total hospitalizations and deaths. In fact, the XBB.1.5 variant may be the highest peak in cases since the emergence of the original omicron variant.
Related: If You Haven’t Gotten COVID Yet, This Might Be Why
Should You Worry About the XBB.1.5 Variant If You're Vaccinated?
With increased transmissibility of XBB.1.5, exposure to COVID-19 infection will increase across the entire population. For those vaccinated and recently boosted with the bivalent vaccines, the risk is reduced as antibody levels will be at a high level and the boosters have improved efficacy against the newer omicron strains than the original vaccine, Dr. Menachery states.
A moderate risk exists for those vaccinated without subsequent boosters as the original vaccines are less effective against all the omicron strains. Additionally, vaccine immunity wanes over time and may only provide partial protection, mostly from severe disease.
For the unvaccinated and immune-compromised, XBB.1.5 represents a significant risk for hospitalization and death, Dr. Menachery adds. Importantly, while treatment with drugs like paxlovid will still be effective, many of the monoclonal antibodies will not be effective against XBB.1.5. This highlights the importance of getting up to date with vaccine and booster doses.
“Being vaccinated is the most important first move to defend yourself against COVID, including XBB.1.5,” says Dr. Li. “So far, the Pfizer and Moderna vaccines appear to be effective against it. That said, many people who are 'vaccinated' received their full vaccinations a year or more ago and are still more vulnerable since vaccine protection wanes with time.”
So, someone who received their vaccine a year ago will not be well-protected. The best defense against XBB.1.5, or Kraken, is to be fully vaccinated and boosted. The bivalent booster is the update that adds an important layer of protection against XBB.1.5. And don't forget that one of the best ways to protect yourself against COVID is simply to wear a properly fitting N95 or KN95 mask when in public, Dr. Li adds, especially when you're indoors.
Next up: 8 Sneaky Symptoms That You Might Not Realize Are Signs of Long COVID
Sources
Dr. Vineet Menachery, assistant professor in the department of microbiology and immunology at the University of Texas Medical Branch
Dr. William Li, MD, doctor, researcher, Angiogenesis Foundation President/Founder and author of New York Times bestseller, Eat To Beat Disease
