People walk past a sign requiring people to wear face coverings in London, Britain, on Dec. 9, 2021. (Xinhua/Stephen Chung)

The World Health Organization's (WHO) Regional Office for Europe on Thursday urged people to exercise caution this holiday season, as the region is now coping with two highly transmissible coronavirus strains that have the potential to overload the already overburdened health systems.

"The European region was the epicenter of the pandemic even before the emergence of Omicron, with surging cases of the Delta variant," Hans Kluge, regional director of WHO Europe, said in a statement.

According to WHO Europe, the threat posed by COVID-19 is as serious as ever, with the highly transmissible Delta variant dominating throughout the region and the Omicron variant spreading rapidly with uncertain consequences.

Kluge noted that experience has shown that it is effective to "exercise caution" alongside the "current tools at our disposal," such as vaccines, booster jabs, testing, masks and distancing, which are proven "stabilizers" and enough to "help us to manage the virus and keep people safe."

"We have come a long way since last year. We have seen inspiring examples of solidarity. We know what works. We know how to keep ourselves and others safe. The emergence of Omicron doesn't change that. WHO Europe is in regular contact with experts across the region and will share further information as soon as it is available."

Kluge attacked mounting misinformation, most recently seen around the Omicron variant in the region. He urged people to "seek out reliable sources of information that provide advice based on the latest evidence and scientific consensus."