Outside of China, many experts have their attention on the US and Omicron subvariant XBB.1.5, which has been detected in 29 countries so far. Maria Van Kerkhove, the WHO’s Covid-19 technical lead, said it was “the most transmissible subvariant that has been detected yet.” However there is no indication as yet that XBB.1.5 — which has been spreading rapidly in the northeastern United States — causes more severe disease than other types of Covid. […]