As China suffers from another wave of infections caused by an Omicron subvariant, another sublineage of this strain called XBB 1.5 has been driving a wave in the United states, where it accounts for almost 40% of the cases. The first case of infection with this variant was found in India on Friday.
Newer version of XBB subvariant
XBB, a variant of concern declared by WHO, is a hybrid of two different Omicron BA.2 subvariant. Though the scientists were still in initial stages of studying the XBB subvariant, they declared that an even newer version of that subvariant had emerged, known as XBB.1.5.
While XBB.1.5 is not more immune evasive than XBB, it does have a higher level of transmissibility, said Yunlong Cao, biochemist at Peking University, NDTV reported. Scientist JP Weiland said: "XBB.1.5 appears faster and more sustained than any of the variants since Omicron's first wave[BA.1] last January."
XBB, subvariants resistant to antibodies formed by vaccination
Yunlong Cao and his colleagues had reported earlier this year that XBB and three other subvariants had become entirely resistant to the antibodies in blood samples from people who were vaccinated or had Covid infections, New York Times reported.
Top US infectious diseases expert Anthony Fauci, in November this year, ahd said that while updated Covid booster shots, which target the original variant of the coronavirus as well as BA.4 and BA.5 subvariants, would provide some protection against the XBB subvariant, it would not be optimal.
XBB agile at evading antibodies: Dr Fauci
Dr Fauci had said that XBB appeared exceptionally agile at evading the antibodies that are created by prior infection or vaccination and that form the body's first line of defense against the virus. He and others, however, he said were encouraged by data showing that countries like Singapore where XBB led to a jump in infections did not report a commensurate rise in hospitalizations.
The World Health Organisation had said in October that the XBB subvariant has a global prevalence of 1.3% and it has been detected in 35 countries. An evidence pointing at a higher reinfection risk, as compared to other circulating Omicron sublineages was also found by the WHO's Technical Advisory Group on SARS-CoV-2 Virus Evolution.
The WHO said that whether the increased immune escape of XBB is sufficient to drive new infection waves appears to depend on the regional immune landscape as affected by the size and timing of previous Omicron waves, and the COVID-19 vaccination coverage.
