ECDC assesses risk to the EU/EEA associated with Omicron XBB.1.5 sub-lineage

In a Threat Assessment Brief released today, the European Centre for Disease Prevention and Control (ECDC) assesses the overall level of risk to the EU/EEA associated with the spread of the Omicron XBB.1.5 SARS-CoV-2 sub-lineage as low for the general population. The risk is moderate to high for vulnerable individuals such as the elderly and non-vaccinated and immunocompromised people, depending on their immunity against SARS-CoV-2. Several knowledge gaps exist with XBB.1.5 and this assessment may change in the coming weeks as more evidence becomes available. 

Mathematical modelling by ECDC indicates that XBB.1.5 could become dominant in the EU/EEA after one to two months, given the current low proportions reported in the EU/EEA and its estimated growth rate. There are currently no signals that the infection severity of XBB.1.5 is different to that of previously circulating omicron sub-lineages. The proportion of XBB.1.5 in the EU/EEA was lower than 2.5% for the final two weeks of 2022 (the most recent period where variant proportions at this low level can be accurately estimated).  In the United States (US), XBB.1.5 is currently spreading 12% faster than other circulating variants.  

The XBB.1.5 sub-lineage is currently present only at very low levels in the EU/EEA but may become dominant in the EU/EEA in the next few months,” said Andrea Ammon, ECDC Director. “In light of this, ECDC recommends carrying out appropriate testing and sequencing, increasing COVID-19 vaccination uptake, and reinforcing infection prevention and control measures. Non-pharmaceutical interventions such as staying home when ill, teleworking, good ventilation of indoor spaces and appropriate use of face masks should also be considered. 

XBB.1.5 is a sub-lineage of XBB, which evolved from two earlier lineages of Omicron, with an additional spike change. It was first detected in the US in October 2022 and has been growing in proportion in the US and many countries around the world since then, including several EU/EEA countries. As of 12 January 2023, ECDC has designated this sub-lineage as a variant of interest. 

ECDC proposes the following options for response to public health authorities in the EU/EEA:    

• Maintain or improve appropriate levels of testing and sequencing of SARS-CoV-2, according to target thresholds as per ECDC/WHO guidance, and timely sharing of data.   

• Carry out appropriate risk communication activities targeted at health professionals and the public, including information about treatment options.   

• Improve the timely uptake of COVID-19 vaccines, including primary course and booster doses according to national guidelines. 

• Consider time-limited and non-pharmaceutical interventions such as staying home when ill, teleworking, appropriate use of face masks and good ventilation of indoor spaces. 

• Follow appropriate infection prevention and control (IPC) guidance for healthcare settings.