‘Kraken’ subvariant of Covid virus could lead to ‘substantial increase’ in case numbers

New version of the virus likely to become dominant one in EU in next few weeks

There is a “moderate chance” that the transmissibility of a new version of the Covid-19 virus will lead to “a substantial increase” in the number of cases of the disease within the next one to two months, according to a new threat assessment by the European Centre for Disease Prevention and Control (ECDPC).

The new XBB.1.5 subvariant of the virus, sometimes referred to as Kraken, has been given a “moderate to high” risk assessment for elderly, non-vaccinated and immunocompromised people by the centre, but has been assessed as low risk for the population generally.

“There are currently no signals that the infection severity of XBB.1.5 is different from that of previously circulating Omicron sub-lineages,” the ECDPC said.

The agency said the XBB.1.5 subvariant was expected to become dominant in the European Union in one-two months’ time but was currently the cause of a very low proportion of the Covid cases in the union. Dominant means more than 50 per cent of all cases.


XBB.1.5 is a subvariant of the Omicron variant. It was first detected in the United States in October 2022 and is spreading in the US 12 per cent faster than other circulating variants.

The proportion of Covid cases linked to the subvariant was as low as 2.5 per cent in the EU area in the final weeks of 2022, according to the ECDPC.

“While there are currently no vaccine effectiveness [VE] estimates for XBB.1.5, the available vaccines still remain effective against severe disease due to previous and current omicron variants dominant in the EU, even though there is some evidence of waning over time,” it said.

Most of the confirmed incidences of the new subvariant are from the US and UK, but instances have also been confirmed in Ireland and other EU/EEA countries, the agency said, citing Austria, Belgium, Czechia, Denmark, France, Germany, Iceland, Italy, the Netherlands, Portugal, Romania, Slovenia, Spain and Sweden.

National authorities have been urged to maintain or improve the testing and sequencing of the virus and the sharing of data.

The ECDPC also recommended the timely uptake of Covid vaccines and that people consider non-pharmaceutical options such as staying at home when ill, teleworking, the use of face masks when appropriate, and good ventilation of indoor spaces.

“The existing vaccines are very likely to continue to protect against severe outcomes for this sub-lineage,” the report said.

Colm Keena

Colm Keena

Colm Keena is an Irish Times journalist. He was previously legal-affairs correspondent and public-affairs correspondent