German Chancellor Angela Merkel has warned that up to 70% of the country's population - some 58 million people - could contract the coronavirus.
Mrs Merkel made the stark prediction at a news conference on Wednesday alongside Health Minister Jens Spahn.
She said since there was no known cure, the focus would fall on slowing the spread of the virus. "It's about winning time," she explained.
Her remarks came as Italy entered its second day of a national lockdown.
Italian Prime Minister Giuseppe Conte announced the closure of schools, gyms, museums, nightclubs and other venues across the country, which on Wednesday passed 10,000 confirmed infections.
Speaking alongside Mr Wieler at a press conference - her first public address on the outbreak - Chancellor Merkel warned that border closures would not be enough to prevent the spread of the virus. She ruled out following Austria's lead in banning visitors from Italy.
"This is a test for our solidarity, our common sense and care for each other. And I hope we pass the test," she said.
Mrs Merkel also said she was open to scrapping Germany's "black zero" rule to allow new government borrowing. She said it was "an extraordinary situation" and that ending the outbreak came first.
However other German health experts say it is unlikely that two-thirds of Germans will end up getting the coronavirus.
Virologist Alexander Kekulé, a former federal government advisor on disease control, told German media that in the worst case scenario a maximum of 40,000 people in the country would get the virus. He said this estimation was based on the number of cases in China, where the rate of new infections is slowing.
He had earlier said that the German government missed opportunities to contain the outbreak further by shutting schools and cancelling events.
Wednesday also saw Berlin city authorities ban all events with more than 1,000 participants until the end of the Easter holidays.
"The coronavirus continues to spread. In such a phase, public life must be restricted," said the city's Health Minister, Dilek Kalayci. "The spread of the coronavirus can be slowed down by reducing major events. At the beginning of an epidemic, such a restriction is important."