New Delhi, Dec 26 : The XBB subvariant of Covid-19's Omicron variant is fast emerging as the dominant type in India, and now it accounts for more than 18 per cent of cases in the US as well. According to the WHO, XBB is a recombined subvariant, a sub-lineage of the Omicron variants BA.2.10.1 and BA.2.75 which means it is a subvariant of the Covid-19 Omicron variant, not a new variant. The WHO says that while further studies are needed, the current data do not suggest there are substantial differences in disease severity for XBB infections. However, early evidence points to a higher re-infection risk compared to other circulating Omicron sublineages. As of now, there are no data to support escape from recent immune responses induced by other Omicron lineages, said the WHO. Moreover, there is currently no epidemiological evidence that points to these sublineages having a significantly higher risk than other Omicron sublines, however, this assessment is based on data from sentinel nations and is not fully generalisable to other settings, it added. XBB has a global prevalence of 1.3 per cent and it has been detected in 35 countries. Among the Indian patients, the disease is mild like with other Omicron sub-lineages, and no increase in severity is noted, according to the Indian SARS Cov-2 Genomics Consortium. Meanwhile, as a WhatsApp message has been making its rounds claiming that the newly discovered XBB subvariant of Omicron is five times more virulent and has a higher mortality rate than the Delta variant, the Union Health Ministry has rejected the claim and has termed the message fake. "This message circulating in many WhatsApp groups regarding XXB variant of Covid-19 is FAKE and Misleading," it said on Thursday. The viral message claims that "the new variant of the Covid-Omicron XBB coronavirus is different, deadly and not easy to detect correctly. The symptoms of the new virus Covid-Omicron XBB are - there is no cough and there is no fever." /IANS