Q:

How can immunity be developed without a vaccine? (re Merkel's speech)

Recently, German Chancellor Angela Merkel gave a speech about the importance of slowing down Covid-19. Among her remarks were

The most important thing, the chancellor said, is to slow down the spread of the coronavirus to win time for people to develop immunity

How does that work? Can immunity be developed without actually catching the disease or via a vaccine?

A:

It's hard to know exactly what another person is thinking, but Merkel is probably referencing herd immunity.
Assuming that people who are infected and recover will be less susceptible to infection in the future (the extent to which is currently unknown), those people have effectively been naturally vaccinated, which can help slow down future spread.

