Polish Health Minister Adam Niedzielski (photo courtesy of his official Twitter account).
"We cannot say that the epidemic threat is receding," Health Minister Adam Niedzielski said after the ministry reported a further 19,366 cases and 504 deaths in the past 24 hours.
"The situation is worrying," Niedzielski said.
The minister announced that public places already restricted to 50 percent of maximum capacity would now only be allowed to have 30 percent.
The limit does not apply for vaccinated people but, if it is exceeded, the venue must be able to prove that it has verified attendees' vaccination statuses, the government said.
Also from December 15, people flying into Poland from outside the EU's free travel Schengen area must have proof of a negative test taken no earlier than 24 hours before crossing the border.
Among other measures, schools will switch to remote learning for a few days on either side of the Christmas holidays, meaning that children will be out of school from December 20 to January 9.
There will be a capacity limit of 75 percent on public transport and nightclubs will have to close.
Poland's right-wing populist government has so far been very cautious about following other European countries in embracing vaccine certificates and mandatory vaccinations.
Vaccination hesitancy is still very high in Poland, a country of 38 million people where only around 54 percent of the population is fully vaccinated ;one of the lowest levels in the EU.
Most of the opposition is calling on the government to impose tougher restrictions and the Left party has presented proposals for obligatory vaccinations for all adults in Poland.