Clinics in Moscow have begun offering booster vaccine shots against COVID-19 as Russian officials struggle to contain the highly contagious Delta variant.
The health ministry on Wednesday recommended clinics begin administering booster doses to people vaccinated six months ago or more, making Russia one of the first countries to begin re-vaccination.
Meanwhile, millions of Moscow residents now need to show proof of vaccination or recovery before being allowed in bars and restaurants.
But as many parts of Europe relax tough restrictions, the World Health Organization has warned against complacency.
The WHO Director General told reporters: "We are in a very dangerous period of this pandemic. In those countries with low vaccination coverage, terrible scenes of hospitals overflowing are again becoming the norm. But no country on Earth is out of the woods yet.
"The Delta variant is dangerous and is continuing to evolve and mutate, which requires constant evaluation and careful adjustment of the public health response."
However, in Barcelona, partygoers gathered on Saturday night despite a new spike in COVID-19 infections in Catalonia; with most new cases there being in people aged 10 to 29 years old.
According to official figures the region has seen more than 5,000 new confirmed cases each of the past three days.
Saturday's figure reached 5,379 infections, leaving the total toll in the region at 726,544.
Engineer Tomas Gonzalez, 27, was among those enjoying a night out.
"We stay calm. We take the necessary precautions", he said.
"We try to stay within the group we've arrived with. We don't talk to other people. And if we see that at a certain moment there are too many people or social distancing isn't observed, either we leave or put our face masks on. That's how we handle it."
In Austria, nightclubs have been opening for two weeks and a midnight curfew was lifted on July the first.
The only rule that remains is that those who attend an event, go to a nightclub, or eat in a restaurant must show proof of either having received at least one vaccination shot more than three weeks ago, recovered from coronavirus, or tested negative.