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The World Health Organisation (WHO) is monitoring the Omicron subvariant XBB.1.16 strain, which is fuelling a recent surge of cases in India. It has also been detected in more than 20 countries, including Singapore, the United States, the United Kingdom and Australia.

It was first discovered in late January, and is a recombinant of two descendants of another BA.2 Omicron variant.

The WHO said the subvariant has one additional mutational mutation in the spike protein. Laboratory studies show that Arcturus has increased infectivity, as well as potential increased pathogenicity.