What is XBB Covid? New Omicron variant that has led to an increase in cases

New variants of Covid create new health problems as Omicron’s relatives XBB and XBB.1.5 have seen an increase in cases in countries around the world.

It comes as UK health experts have suggested up to 9,000 people are dying from Covid every day in China, where infections have skyrocketed after the country ended its strict lockdown rules.

The surge has prompted the UK government to require all passengers arriving in England from China from January 5 onwards to have a negative Covid test before travel.

So what are the sub variants of the XBB and where have they been seen? Here’s everything you need to know:

XBB is a sub-variant of the Omicron BA.2 variant and XBB.1.5 is a sub-variant of the XBB.

It emerged as a “recombinant strain among second-generation Omicron variants,” writes Professor Kei Sato in a study from the University of Tokyo, Hokkaido University and Kyoto University posted on preprint server bioRxiv.

Japanese researchers have studied the properties of XBB in hamsters, including transmissibility and immune resistance.

Their results indicate that the variant is highly transmissible and has developed immunogenic resistance.

In October 2022, the World Health Organization (WHO) also said that there was early evidence to suggest that XBB had an increased risk of re-infection, compared to other circulating sub-variants of Omicron.

However, in a November fact-checking article by Reuters, his team concluded that there is no evidence that XBB is “more deadly or causes more severe COVID-19 than the delta variant.”

Where have XBB cases been reported?

Omicron’s variants have taken the US by storm, as together they accounted for 44.1% of the country’s total cases in the week ending Dec. 31.

The sub variants were previously reported as XBB only prior to this week.

While sub-variants currently predominate in the Northeast, they account for less than 10% of infections in many other parts of the country, according to the US Centers for Disease Control and Prevention (CDC) on Friday.

XBB.1.5 has been detected in at least 74 countries and 43 US states, according to outbreak which uses data from the Global Initiative for Avian Influenza Data Exchange (GISAID).

These countries include the UK, China, India, Pakistan, Indonesia and Australia.