YOUth should know: The XBB.1.5 COVID-19 subvariant and its transmissibility

4 things about the new variant that was first detected in October 2022.

Sherlyn Sim

Considers knowing how to use a rice cooker an achievement.

Published: 9 January 2023, 5:32 PM

Since Omicron was first discovered in November 2021, many different subvariants of it have been reported all over the world. 

The latest on this list is the XBB.1.5 subvariant, which the World Health Organisation (WHO) said “appears to be growing quickly in some geographies”.

Here are 4 things youths should know about this new subvariant:

1. What the XBB.1.5 variant is

According to WHO, XBB.1.5 is a subvariant of the Omicron variant of COVID-19, and was first discovered in October 2022.


There have been five COVID-19 variants of concern to date, including Alpha, Beta, Gamma, Delta and Omicron. PHOTO CREDIT: CDC VIA UNSPLASH


XBB.1.5 is a sublineage of XBB, a recombinant, or fusion, of two BA.2 sublineages, which are both sublineages of the Omicron variant of COVID-19.

Transmission of XBB.1.5, along with other respiratory viruses and variants of COVID-19, are expected to increase due to the holiday period.

2. How XBB.1.5 differs from previous variants

WHO announced that XBB.1.5 is the most transmissible subvariant that has been detected as of Jan 4.


The older XBB variant was detected in Singapore in September 2022. PHOTO CREDIT: SHAWNANGGG VIA UNSPLASH


It is highly transmissible due to the mutations within this subvariant of Omicron which allow it to adhere to the cell and replicate easily. 

WHO says that it is concerned that the more it spreads, the more chances it has to change and mutate.

There is currently no data on the severity of XBB.1.5, but WHO says that there is no indication that severity has changed with this new subvariant.

3. Countries where XBB.1.5 has been detected since Jan 4

XBB.1.5 has been detected in 29 countries, including the United States (US), South Korea, Australia and the United Kingdom. It is quickly replacing other subvariants in circulation in some of these countries.

According to the United States Centers for Disease Control and Prevention, it made up about 27.6 per cent of COVID-19 cases in the US as of Jan 7. 


As of Jan 5, there are 628 counties, districts, or territories in the US with a high COVID-19 Community Level, according to the US CDC. PHOTO CREDIT: MARTIN SANCHEZ VIA UNSPLASH

4. How current vaccines fare against XBB.1.5

Similar to XBB, XBB.1.5 is shown to have immune escape, meaning it can escape detection from a person’s immune system.

However, Dr Maria Van Kerkhove, technical lead on COVID-19 at WHO, said that “countermeasures continue to work”.


According to WHO, good surveillance, good vaccine coverage and a high level of health systems readiness and resilience are important to continue to combat new waves of COVID-19. PHOTO CREDIT: MUFID MAJNUN VIA UNSPLASH


WHO reiterated the importance of vaccination, including booster doses, to protect against hospitalisation, severe disease and death.

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