XBB variant, spreading fast in Singapore, detected in Tokyo

Six cases of the highly transmissible coronavirus variant XBB have been detected in Tokyo, according to the metropolitan government’s COVID-19 infection monitoring committee. XBB — a virus formed from a combination of the omicron subvariants BA.2.75 and BA.2 — was first reported by Singapore in September and has since been confirmed in 35 countries. The subvariant features several mutations in its spike protein — the part of the coronavirus that latches onto cells to gain entry — giving it an exceptional ability to evade immunity acquired through past infections or vaccination. But its severity is not yet known, the monitoring committee said Thursday.