- Feb 11, 2023
- 2 min read

Not Just Another Omicron Variant - Why You Should Be Concerned About XBB1.5

With so many COVID-19 variants emerging in the last 3 years, you may be tempted to disregard the latest Omicron variant XBB1.5.

But before you skip this article, you should know that XBB1.5 may be the most contagious variant yet.

You can be susceptible to infection by this strain even if you had received vaccinations or had previous infections, hence making it very contagious.

Here are 3 things you should know about XBB1.5.

Why is XBB1.5 more contagious?

XBB1.5 contains more mutations that allow it to evade antibodies produced from vaccination or after a previous infection.

Usually, mutations which enable viruses to avoid antibodies, such as that of parent variant XBB, renders the virus unable to bind itself to human cells as effectively. But XBB1.5 has managed to do both, where it is also able to bind to human cell receptors much more efficiently than other variants.

So, while previous variants took about 4 to 6 weeks to spread widely enough to become one of the most frequently found strains among confirmed cases in the U.S., this one only took a couple of weeks.

As of Jan. 9 2023, COVID-19 caused by the XBB1.5 subvariant accounted for about 25% of confirmed new cases in the U.S.

Does this mean vaccines and boosters are not effective against XBB1.5?

Definitely not! The purpose of COVID-19 vaccines and boosters is not only to prevent infections but to also reduce the severity of infections. Having increased levels of antibodies in the blood and respiratory tract brought about by vaccines can tackle the virus more effectively, leading to milder symptoms even if infected.

Hence, getting a COVID-19 booster is still highly recommended for protection.

What are the symptoms and are they more severe than infections from previous strains?

So far, there is no evidence that suggests XBB1.5 causes more severe illness than previous COVID-19 strains. Experts also believe that symptoms are very similar to other Omicron variants: