The World Health Organization (WHO) has urged Europeans to wear masks during family gatherings at Christmas.
It said Europe was at "high risk" of a new wave of coronavirus infections in the early part of 2021, as transmission of the virus remained high.
Countries across the continent have been registering thousands of daily cases and hundreds of deaths.
Germany was among countries tightening restrictions on Wednesday, closing schools and non-essential businesses.
Meanwhile European Commission President Ursula von der Leyen said the first Covid vaccine would be authorised for use within a week.
Ms von der Leyen told the European Parliament the Pfizer/BioNTech vaccine - developed in Germany - would be rolled out for the bloc immediately, more than a week earlier than originally envisaged.