BERLIN — Chancellor Angela Merkel is on her way out and her power is waning, but in her typically low-key, no-nonsense manner, the German leader on Wednesday laid out some cold, hard facts on the coronavirus in a way that few other leaders have.

Two in three Germans may become infected, Ms. Merkel said at a news conference that reverberated far beyond her country. There is no immunity now against the virus and no vaccine yet. It spreads exponentially, and the world now faces a pandemic.

The most important thing, the chancellor said, is to slow down the spread of the coronavirus to win time for people to develop immunity, and to prevent the health care system from becoming overwhelmed.

“We have to understand that many people will be infected,” Ms. Merkel said. “The consensus among experts is that 60 to 70 percent of the population will be infected as long as this remains the situation.”