The president of the Robert Koch Institute (RKI), Lothar Wieler, on Friday warned that Germany has reached a difficult moment in the pandemic.
"The downward trend (in cases) is no longer continuing," said Wieler at a press conference in Berlin. "The nationwide 7-day incidence is no longer declining everywhere."
It looks as if some federal states are heading for a plateau "but the plateau is still too high", he said.
Wieler said the B 1.1.7 virus variant first discovered in Britain was spreading rapidly in Germany, and that controlling the pandemic was becoming more difficult.
"Nevertheless, we can and must manage to keep the virus in check," he said, adding that people had to stick to the current measures.
"Please also wear a mask in the car, in the office and on public transport," he said. "Limit your contacts to the bare minimum."
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'Back to Christmas Covid levels'
Wieler warned against opening public life up too quickly.
"The virus has been given a boost, any ill-considered relaxation will set us back - then in a few weeks we'll be back to where we were at Christmas," he said.
The number of new infections per 100,000 residents in seven days stood at 56.8 nationwide - slightly lower than the previous day (57.1), the RKI said on Friday. In the past days there has been no significant drop in this number. Some areas are also seeing a major increase in cases with the variant - including in Flensburg.
The federal and state governments are aiming for an incidence rate of less than 50, with further opening steps possible at less than 35 new cases per 100,000 residents in seven days.
At the peak of the second wave just before Christmas the incidence was at nearly 200. Wieler said he expects more cases among younger people in the coming weeks because the British variant is more contagious.
"More young adults, adolescents and children will fall ill," he said.
He reiterated that vaccinations are an important tool in the fight against the pandemic. It came after there were reports of some people in Germany refusing the AstraZeneca vaccine.
"All vaccines available in Germany are safe and effective. All of them protect against Covid-19 disease, and as far as we know, they also protect against the new variants."
'The virus doesn't give up' Health Minister Jens Spahn, of Angela Merkel's Christian Democrats, also stressed that the situation was tense.
"The virus just doesn't give up," Spahn said.
He said the need for an end to the lockdown in Germany is "palpable, almost tangible", but added that the country must move forward cautiously "in order not to gamble away what has been achieved".
However, Spahn said some districts with very low figures (such as under 10 new cases per 100,000 residents in seven days) could be allowed to start opening up locally.
Germany has been in a state of shutdown since November, with most of public life now closed and people urged to cut contact to a minimum. Pressure from the business community has been mounting to get public life back on track. Chancellor Merkel was on Friday talking to local politicians about the reopening debate.
But fears of a possible third wave in Germany are growing. Calls for a relaxation of the lockdown are countered by speculation about tougher measures. RKI head Wieler recently spoke to a German broadcaster about a race between vaccinations and virus variants.