KUALA LUMPUR (Oct 27): Omicron continues to evolve with more than 300 sublineages that the World Health Organization (WHO) is tracking, according to the agency’s  Covid-19 technical lead Maria Van Kerkhove.

In her Twitter feed on Wednesday (Oct 26), she said the concern is the increased growth rate and risk of re-infection.

“So far we do not detect changes in severity, but available data is limited,” she said.

Van Kerkhove said She said that at present, Omicron variants of concern are dominant around the world, with almost 80% of the sequences reported being the BA.5 and their sublineages.

"XBB is a recominant of actually two BA.2 sublineages, and specifically BA.2.10.1 and BA.2.75.

"It's one of the more than 300 sublineages of Omicron that we and our partners are tracking worldwide," she said.

She added that it is receiving attention and rightly so, because the experts see a growth advantage of XBB as well increase in case detections in some countries.

"We don't see signals of a change in severity of the CBB recombinant, so it is still [at a] low level of circulation but we need to keep an eye on it," she said.