Germany’s health minister said on Thursday that he expects a surge in coronavirus cases around New Year and that people will likely need a fourth vaccine shot to maintain the best immune response against Covid-19.

Health Minister Karl Lauterbach told public radio network WDR 2 that Germany hasn’t yet seen a big, rapid wave of new infections from the omicron variant like some other European countries.

“That will change around New Year and in the first week of January,” Lauterbach said.

The government is urging Germans to limit their contacts over the holiday period and to get vaccinated, including with booster shots if they’ve already had their initial vaccines.

Official figures show 70.7% of the population have received a full course of vaccine, while 35% have had boosters.

Demonstrations against new pandemic restrictions and a planned vaccine mandate have flared up in Germany over the past weeks.

Police said about 5,000 protesters gathered in the centre of Munich late on Wednesday, with some participants attacking officers. Eleven people were detained.

Prosecutors in Bavaria state said that authorities are investigating two doctors who are suspected of providing false vaccination certificates to people who were unwilling to be jabbed against Covid-19, and administered diluted vaccines to other patients without their knowledge.

Officials have written to advise almost 1,000 people in the Passau region to get tested for antibodies to determine whether or not they were properly vaccinated.