The World Health Organization 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.
A statement from the WHO's European regional office said that the massive increase in gatherings of families and friends across Europe during the winter holiday season brought a significant risk of increased Covid-19 transmission.
It urged individuals, families and communities to play their part to prevent another resurgence of cases.
Family gatherings should be held outside if possible, and if indoors participants should wear masks and practice social distancing, it said.
"It may feel awkward to wear masks and practise physical distancing when around friends and family, but doing so contributes significantly to ensuring that everyone remains safe and healthy," the WHO added.
"Vulnerable people and older friends or relatives may find it very difficult to ask loved ones to stay away physically, regardless of the anxieties or concerns they may have. Consider what others may be feeling and the difficult decisions they will be facing."
The statement also urges people to avoid crowded public transport, and suggests that countries with ski resorts take steps to adapt them to avoid crowding during the skiing season.
What are Germany's new measures, and why now?
Only essential businesses such as supermarkets and banks will be allowed to remain open in the new lockdown in Germany, which will be in place until 10 January.
Christmas will see a slight easing, with one household allowed to host up to four close family members.
Restaurants, bars and leisure centres have been shut since November and some areas of the country had imposed their own lockdowns.
Hair salons are among the businesses which must close, while drinking alcohol in public places, such as at popular mulled wine stalls, is forbidden. Companies are being urged to allow employees to work from home.
The 952 new fatalities and 27,728 cases announced on Wednesday are a new peak for Germany's pandemic, but may cover numbers that were not included in previous days' statistics.
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