Last week, the Met canceled performances through March 31, part of a wave of temporary closures of theaters and concert halls around the world in response to the outbreak. But after the Centers for Disease Control recommended on Monday that gatherings of more than 50 people be avoided for at least eight more weeks, organizations began to extend those closures.

Carnegie Hall canceled its performances through May 10, and Adam Crane, a spokesman for the New York Philharmonic, said in an email that the orchestra “will be making a significant announcement at the beginning of next week regarding the status of the rest of our season.”

Throughout the country, arts organizations that have been shut by the pandemic have been dealing with the question of how to compensate employees. Some have chosen not to invoke what are known as contractual “force majeure” clauses, which give institutions substantial latitude to withhold compensation if they have been closed by forces beyond their control.

“We’re negotiating with companies around the country,” said Mr. Egert of the union. “And they’ve really ranged. Some of the smaller companies, like Sarasota Ballet, are paying all of their artists through the season.”

But Mr. Gelb said that would be impossible for an opera company the size of the Met, which despite its $308 million annual budget has little financial cushion. (Its endowment, valued at $284 million in 2018, is less than a tenth the size of the Metropolitan Museum’s.)