Key points to remember
- The XBB variant of COVID-19, which originates from the BA.2 subline of the SARS-CoV-2 virus, is slowly gaining traction around the world and increasing COVID-19 cases in some countries.
- In the US, New York could be an emerging hotspot for XBB streaming.
- More data is needed to understand XBB, but early evidence suggests the risk of reinfection may be higher and it may not respond to some COVID treatments.
Worldwide, the Omicron variant of COVID-19 is still the dominant circulating variant of the SARS-CoV-2 virus. However, the virus still evolves into different subvariants, each with its own specific mutations.
One subvariant of Omicron that is beginning to gain global attention is XBB, which comes from the BA.2 sublineage of the COVID virus.
How was XBB born? Andy Pekosz, PhD, a virologist and vice chair of the Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health, told Verywell that since XBB is a combination of the BA.2.10.1 and BA .2.75, this means that the subvariant contains parts of two different viruses that infected the same host and swapped some of their genes in the process.
But there is no need to panic. According to the World Health Organization (WHO) Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE), XBB is considered part of the Omicron variant. The group concluded that XBB and its sublines do not need a new label or be designated as a New Variant of Concern because they are not significantly different from other Omicron sublines.
Where XBB Spread
As of October 2022, XBB has been detected in 35 countries, including the United States. The subvariant has recently led to an increase in COVID cases in Singapore and has also been responsible for numerous cases in India, Australia and South Korea.
Spread in the United States
It is too early to tell if XBB will cause a surge in the United States. However, Raj Rajnarayanan, PhD, assistant dean of research and associate professor at the Arkansas State University campus of the New York Institute of Technology, told Verywell that New York is an emerging hotspot. for the propagation of XBB and its sub-lines.
Pekosz said we don’t know how well XBB will compete with current Omicron variants in the US. But we know that other subvariants like BQ.1.1, BF.7, and BA.2.75.2 have similar mutations, and they increase in size. Therefore, he said XBB is worth watching carefully.
Whether XBB will cause an increase in infections might depend somewhat on a region’s immune landscape, which includes factors such as COVID vaccine coverage and the size and timing of previous Omicron waves.
Why do viruses mutate?
Mutating viruses sounds scary, but it’s a normal thing for them. When a virus mutates, it means that parts have changed in appearance or action, which sometimes results in an improved ability to infect a host (such as a person or animal). This may include a better ability to avoid efforts to stop them, such as vaccines and treatments. Different things cause viruses to mutate, such as people’s behaviors (which may be hosts the virus wants to infect) and environmental fluctuations (such as changing seasons).
For example, mutations have altered the spike protein of the COVID virus. As a result, vaccines and treatments have also had to adapt.
Is XBB more contagious or more serious?
Pekosz pointed out that COVID cases were increasing in a highly vaccinated population in Singapore, suggesting that XBB might be more transmissible.
Risk of reinfection
Diana Finkel, DO, assistant professor in the Department of Medicine and director of the infectious disease fellowship program at Rutgers New Jersey Medical School, told Verywell that compared to other Omicron sublines in circulation, early evidence suggests that there might be a higher risk of re-infection with XBB. In other words, even if you’ve had COVID before, there’s a chance you’ll be re-infected with the XBB variant.
People who were re-infected with XBB initially contracted COVID before the Omicron period. However, we need more data to know for sure whether or not XBB escapes Omicron immunity.
Finkel said that while there is no evidence yet that XBB will pose a higher risk than other Omicron subvariants, we should always be on the lookout and keep an eye on the news rate. infections.
Is XBB tougher?
Currently, there is no evidence that XBB causes more severe COVID disease. However, people should keep in mind that there are many factors that influence how sick someone will be if they get COVID, not just which variant they get.
Will vaccines and treatments work against XBB?
Pekosz said that although Singapore has seen a large number of COVID cases, there has not been a sharp increase in hospitalizations. This could suggest that COVID vaccines may still offer protection against serious illnesses – around 92% of Singapore’s population is fully vaccinated and 80% have received their boosters.
Yet, it appears that recombinant XBB.1 is more resistant to neutralizing antibodies induced by booster doses than other circulating subvariants like BA.4/5, BQ.1.1 and BA.2.75.2.
Early data shows that the immune response induced by a bivalent COVID booster was enhanced in people who already had COVID. However, the results are based on preliminary evidence and further studies are needed.
The drugs we currently have to treat COVID are expected to still be effective against circulating variants and XBB. However, Finkel said Evusheld (a combination of monoclonal antibodies tixagevimab and cilgavimab) might not work as well.
In a preprint study published in medRxiv, the researchers said that XBB is one of the most antibody evasive mutations they have tested and shows strong antibody resistance. These convergent Omicron mutations can evade neutralizing antibodies (NAbs) (such as Evusheld and Bebtelovimab) and convalescent plasma.
Health agencies around the world are keeping a close eye on the XBB variant and trying to learn as much as possible about it.
For now, the best step you can take to protect yourself from COVID is to get a dual booster when you are eligible. The updated shots provide better protection against the Omicron variant than previous monovalent booster vaccines.
What this means for you
Preliminary research suggests that the XBB subvariant of Omicron may carry a higher risk of infection and be more resistant to neutralizing antibodies from booster vaccine doses and antibodies, but further studies are needed.
For now, the best way to protect yourself against COVID is still to get vaccinated and boost.
The information in this article is current as of the date indicated, which means that more recent information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
Verywell Health only uses high quality sources, including peer-reviewed studies, to support the facts in our articles. Read our editorial process to learn more about how we fact check and ensure our content is accurate, reliable and trustworthy.
World Health Organization. TAG-VE statement on Omicron BQ.1 and XBB sublines.
Callaway E. COVID’s “variant soup” makes winter surges hard to predict. Nature. 2022;611(7935):213-214. doi:10.1038/d41586-022-03445-6
Grubaugh ND, Petrone ME, Holmes EC. We shouldn’t worry when a virus mutates in outbreaks. Nat Microbiol. 2020;5(4):529-530. doi: 10.1038/s41564-020-0690-4
World Health Organization. TAG-VE statement on Omicron BQ.1 and XBB sublines.
Singapore Ministry of Health. Immunization statistics.
New South Wales Agency for Clinical Innovation. Living proof – SARS-CoV-2 variants.
Yunlong C, Fanchong J, Jing W, et al. Imprinted SARS-CoV-2 humoral immunity induces convergent evolution of Omicron RBD. bioRxiv. Preprint uploaded October 30, 2022. doi:10.1101/2022.09.15.507787
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