A rapidly spreading Covid strain has been dubbed the Nightmare Variant after it was found to double infections in a matter of days.
The mutant strain formally known as XBB is said to be one of a 'slew' of new variants been shown to easily evade immunity from vaccines and infections. The strain has been detected in 17 countries in Asia and Europe, with a handful of cases in the US.
Nicknamed the Nightmare Variant by some media in Asia, because of its rapid spread, experts have said there are no signs it causes more serious illness, although it appears resistant to treatments, Wales Online reported.
UC Berkeley infectious disease expert John Swartzberg told the San Francisco Chronicle : "We are seeing a slew of new variants that are using a similar approach to survive - they are finding ways to evade the way we get immunity from vaccines and previous infection with changes on the spike protein."
He added: "XBB is no different from the others."
It comes as concerns grow in the US about newly detected Omicron sub-variants BQ.1 and BA1.1 that could drive another winter surge.
XBB was first found in India in August and has since been found in Bangladesh, Japan, Singapore and at least 13 more countries - including Australia and Denmark. It has also been found in Hong Kong.
Singapore Ministry of Health said XBB went from being responsible for 22% of cases to being responsible for 54% of cases in one week. Some 79% of people in Singapore are fully vaccinated.
Singapore saw the number of new cases of Covid double from 4,719 on 10 October to 11,732 on October 11, according to Johns Hopkins' Coronavirus Resource Center.
Singapore health minister Ong Ye Kung said the country is likely to see 15,000 daily cases on average by mid-November.
XBB is a mutation on Omicron BA.2. 23 cases of XBB have been detected in the USA.
Natalie Thornburg, CDC lead respiratory virus immunology specialist said: "XBB is a chimera. I think there have been a couple of sequences identified in the United States. But it’s way, way, way, way below that 1% threshold. I mean, it’s really like a handful of sequences."
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