US: A new COVID variant that was first detected last year has quickly become the dominant strain in the US - and picked up a creepy moniker along the way. Nicknamed the “Kraken variant” by some XBB.1.5 has now been identified in at least 29 countries, according to the World Health Organization.
XBB.1.5 is a descendant of the omicron XBB subvariant - which is itself a cross between two earlier strains: BA.2.75 and BA.2.10.1. The original XBB variant has already caused waves of infection in countries including Singapore and India since the WHO first raised concern about it last October.
While accounting for just 1% of all COVID cases at the start of December, estimates from the US Centers for Disease Control and Prevention show that it surged to become the dominant strain by the end of the month, responsible for about 41% of all infections. In northeastern states, that figure has jumped above 70%.
XBB.1.5 is “the most transmissible sub-variant which has been detected yet,” said WHO’s COVID-19 technical lead, Maria Van Kerkhove, during a press conference on January 4. While only 29 countries have reported cases caused by it, health authorities are warning it could be much more widespread and silently proliferating thanks to a drop-off in testing.
In other countries, the proportion of infections caused by XBB.1.5 has remained lower, although the picture may rapidly change. Estimates from the Wellcome Sanger Institute found that the variant made up around 4% of COVID infections in England as of mid-December, while Canada has found a handful of such cases.
The WHO plans to release an updated assessment on the variant’s risks in the coming days.
COVID-19 variants are currently named by an expert group convened by the WHO.
It identifies so-called variants of concern that have potential global public health significance, such as reducing the effectiveness of current pandemic measures, using the Greek alphabet. Previous strains like alpha, beta and delta fell under the convention.
But the last Greek-named variant, omicron, emerged more than a year ago and left no room for the emergence of other, significantly different strains.
Omicron has spawned multiple lineages, including XBB 1.5, and their names stem from a mix of alphabets and numbers known as “Pango.” That has led to the rise in popularity of informal online nicknames, including “Kraken.”
- BLOOMBERG
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