The World Health Organisation is warning Europe to expect a third wave of coronavirus infections next year as a result of its premature lifting of restrictions.
WHO envoy David Nabarro said the "missed opportunities" by European countries to prevent a second wave may now lead to a third in early 2021.
"They missed building up the necessary infrastructure during the summer months, after they brought the first wave under the control," Mr Nabarro said.
"Now we have the second wave. If they don't build the necessary infrastructure, we'll have a third wave early next year."
On Saturday, cases in Germany and France rose by a combined 33,000, Switzerland and Austria are recording thousands of cases a day, and Turkey reported a record 5,532 new infections.
Mr Nabarro singled out Switzerland's move to allow skiing, with masks required in gondolas, while other alpine nations such as Austria closed resorts.
He said Switzerland could reach a "very high level of sicknesses and deaths".
"Once the infection rates sink, and they will sink, then we can be as free as we want," Mr Nabarro told Swiss newspaper Solothurner Zeitung.
"But right now? Should ski resorts open? Under what conditions?"
Mr Nabarro praised the response of Asian countries such as South Korea, where infections are now relatively low.
"People are fully engaged, they take on behaviours that make it difficult for the virus," he said.
"They keep their distance, wear masks, isolate when they're sick, wash hands and surfaces. They protect the most endangered groups."
And Asia did not relax restrictions prematurely, he said.
"You must wait until case numbers are low and stay low," Mr Nabarro said. "Europe's reaction was incomplete."
On Monday, UK Prime Minister Boris Johnson is expected to outline tougher localised restrictions for after England's national lockdown is lifted on December 2.
France has announced a three-stage lifting of restrictions, starting about December 1, followed by a second phase at Christmas and a third from January.