The Omicron coronavirus variant is expected to overtake the currently-dominant Delta strain and cause over half of all Covid-19 cases in the bloc within the “next few months,” an EU health agency has said.

An early risk assessment of the Omicron ‘variant of concern’ (VOC) was released by the European Centre for Disease Prevention and Control (ECDC) on Thursday. The new strain is expected to spread rapidly across the bloc in the months to come, challenging the dominance of the Delta strain, which itself had effectively wrestled out all other variants of Covid-19.

“Current evidence on transmissibility, severity, and immune escape is highly uncertain for the Omicron VOC. However, preliminary data from South Africa suggest that it may have a substantial growth advantage over the Delta VOC,” the watchdog said.

If this is the case, mathematical modeling indicates that the Omicron VOC is expected to cause over half of all [coronavirus] infections in the EU/EEA within the next few months.

The Omicron strain was identified as a VOC by the World Health Organization (WHO) last week. The new variant was first detected in Botswana early in November and is believed to have already become dominant in southern Africa.

While little is yet known about its properties and potential impact, Omicron has been flagged as a heavily-mutated strain, with experts warning it has apparently become well-adapted to interact with human cells.

The new variant has already spread to more than 20 countries around the world, including multiple EU nations and the US. The emergence of Omicron has prompted new restrictions, including travel bans from the hotbed region, rolled out by multiple countries worldwide, including all the 27 EU members, as well as the US and the UK.