Scientists identify new Covid subvariant that is best yet at beating immune system

‘XBB’ is believed to be more contagious than any previous variant or subvariant

A new Covid subvariant that is rapidly spreading in Singapore is believed to be the most effective yet at evading human immunity systems, scientists warn, and is not impacted by a wide variety of established drug therapies and vaccines.

The subvariant, dubbed XBB, is reportedly more contagious than previous variants or subvariants and has spread to more than 17 countries, including Australia, Singapore, Denmark and Japan.

Singapore’s health ministry, in a statement on 15 October, said the subvariant was first spotted in India in August.

Hong Kong detected its first cases of XBB in the first week of October.

“It is likely the most immune-evasive [subvariant] and poses problems for current monoclonal antibody-based treatments and prevention strategy,” Amesh Adalja, a public-health expert at the Johns Hopkins Center for Health Security, was quoted as saying by the Daily Beast.

“Even with immune-evasive variants, vaccine protection against what matters most – severe disease – remains intact,” Mr Adalja said.

In Singapore, the XBB subvariant was likely responsible for dramatically driving the number of Covid cases from 4,719 on 10 October to 11,732 cases, or more than double, the following day, according to Johns Hopkins’s Coronavirus Resource Center.

Daily cases reported in the country have not gone below the 9,000 mark since 11 October. XBB is now the predominant subvariant in the country and accounted for 54 per cent of local cases from 3-9 October, reported Channel News Asia.

Singapore health minister Ong Ye Kung told a press conference that current Covid cases will likely peak by around mid-November. “This is likely to be a short and sharp wave," Mr Ong said, adding that the country is likely to see about 15,000 daily cases on average by mid-November.

He added that on certain days when more cases tend to be reported, the caseload could reach 20,000 or 25,000.

Meanwhile, as XBB appears to be gaining more ground in Asia, BQ.1.1 – referred as the close cousin of XBB – is spreading in Europe and some US states as well.

“There have been times when different variants were on the move in different parts of the world, like the Gamma variant in South America, and Beta in South Africa,” Dr Eric Topol, professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute, was quoted as saying by Fortune.

“But this is different because now we have variants with extreme levels of immune evasion, and in any given country, potentially a few that could be in play at the same time,” he added.

Experts have also warned that a “swarm” of new Covid subvariants could drive a fresh wave of infections across Europe and North America by the end of November.