SAN FRANCISCO — Gov. Gavin Newsom on Sunday called for what he called “profoundly significant steps” to limit the spread of coronavirus, including the isolation at home of all residents 65 years and older; the closure of nightclubs, wineries and bars; and the purchase by the state of hotels to shelter some of the state’s 150,000 homeless people.

The orders in the nation’s most populous state came as governors across the country began to impose further limits on public gatherings in an attempt to slow the spread of a virus that has already claimed nearly 60 lives in the United States.

“We need to meet this moment aggressively,” Mr. Newsom said. “The most important thing is to protect our most vulnerable.”

Around five million seniors in California would be affected by the guidelines, which also apply to people with certain chronic health conditions.