The theater started looking for a solo pianist to play a piano reduction of the complex score, which was written for one of the largest ensembles in opera and is often performed by more than 100 players. “We had a sold-out house, so the intendant of the theater called me that morning at 9 a.m. to ask me to play,” recalled the head of the theater’s music staff, Valeria Polunina.

Ms. Polunina knew the piano score well, but feared she could not do it justice by that evening. But she began working on it, and grew more comfortable, so when she got another call that afternoon saying that the show could not go on without her, she agreed to play.

“It was an adventure,” she said, estimating that she played the piano more than 10 hours straight that day between her all-day practicing and the performance that evening. “There was a full house, and they were so appreciative, with everything canceled.”

Many events in Switzerland were canceled after the government banned performances before more than 1,000 people. The Zurich Opera House, which holds more than 1,100 people, found a novel solution to allow it to perform: It limited audiences to 900 people, buying back tickets when necessary, as it had to this week with some performances of Puccini’s “La Bohème.”

But the company did have to cancel one of its biggest fund-raisers of the year, the Opera Ball, which had been expected to draw 1,600 people on March 14. Bettina Auge, a spokeswoman for the company, said that while it was offering refunds, the opera hoped that patrons would waive the refund as a way to support its educational programs.

Even television, the ultimate home entertainment, is adjusting to the coronavirus, at least in China: On many shows, live audiences are out. A musical reality show called “Singer” that used to feature performers before a live audience and a panel of judges recently broadcast an episode in which the judges and other contestants called in from home, the BBC reported. And some talk shows are being streamed from home, almost like video conferences.