Opera has been forced to forgo its love of packed stages, large orchestras and sold-out crowds, for now.LONDON — It’s an evening of drinking and revelry at Café Momus. A group of young men chatter away as a femme fatale tries to get their attention, jumping on tables and tossing undergarments. But the night spot is not as crowded as usual. There are few waiters in attendance, and by the windows in the back three patrons dine alone.It is Act II of a pared-down production of Puccini’s “La Bohème” at the Royal Opera House. In light of pandemic restrictions, the orchestra has 47 players, down from the usual 74. The act opens with only 18 of 60 chorus members onstage, the rest singing from the wings, and 10 (not 20) children onstage. There are four, not 10, waiters in the cafe.“The cafe scene feels less ‘bustling belle epoque cafe’ and more ‘lonely-hearts establishment’ at the moment, simply because there’s a limited number of people that we can have in the Cafe Momus,” Oliver Mears, the house’s director of opera, said a few days before the June 19 premiere. “It’s just adapting to the circumstances that we were faced with.”Andrew Macnair as Parpignol, with members of the Royal Opera Chorus, in a scene from Act II. Tristram Kenton/Royal Opera HouseMr. Mears said opera is an art form that breaks every social-distancing rule, relying on “crammed pits,” large and dense onstage crowds, moments of intimacy between performers, singing (which can spread viral particles) and a sellout audience. “All of these things really work against us,” he said.“If you were someone who hated opera and you wanted to devise a disease that hit opera particularly hard, then you’d probably come up with something rather like Covid,” he added.The global coronavirus outbreak has had a drastic effect on the performing arts, and opera, which is expensive, has suffered hugely. Many of Europe’s major houses have received government help — in addition to annual taxpayer-funded grants — to avoid insolvency.The Royal Opera House, which was closed for 14 months, received a government loan of 21.7 million pounds (about $29 million) in December, part of a recovery package for arts organizations. The house attracts an average of 650,000 people a year and presents films and screenings in Britain and in 42 countries around the world.Last October, it sold a 1971 David Hockney portrait of its former general administrator, David Webster, for £12.8 million (about $18 million). But even that was not enough to avoid cuts, and 218 staff members were let go.The Royal Opera decided to sell a David Hockney portrait of its former general administrator, David Webster, for £12.8 million to help make up for losses. Facundo Arrizabalaga/EPA, via ShutterstockSince the house reopened on May 17, it has been operating at roughly a third of capacity to ensure socially distanced seating — just over 800 spectators, down from 2,225, Mr. Mears said. He described the mood in-house as “enthusiasm tempered with caution.” (Pandemic restrictions are in place until at least July 19.)The Paris Opera, which also incorporates a world-renowned ballet company, has faced similar threats in the pandemic. In an interview, Alexander Neef, its director, said the opera house had received €41 million (about $47 million) in aid for 2020, leaving it with a €4 million deficit.This year, the Paris Opera is due to receive another €15 million in state aid, he said, to help offset a projected annual loss of €45 million.“Everybody’s exhausted from more than a year of crisis,” Mr. Neef said. The Paris Opera reopened May 19, and since early June has required all audience members to show a “pass sanitaire” (health pass) proving vaccination, a negative test or one proving post-Covid immunity.There was “great appetite when we reopened,” he said on June 22, but “it’s been a little bit flat now,” whether because of the health pass requirement or the good weather and the reopening of cafe terraces.“There’s still a lack of perspective as to how this can actually come to an end,” he said. The hope was that by the fall, “we will be back to whatever this new normal will be. But there’s no guarantee for that right now. We don’t have visibility.”Opera houses in the United States, which depend mainly on private philanthropy and ticket sales for survival, are suffering even more. The Metropolitan Opera in New York, which plans to reopen in September, announced on its website that it had lost $150 million in earned revenue because of the pandemic.Ms. de Niese said pandemic restrictions meant having “to do all of our rehearsals with a mask on, and that is a killer.”Tristram Kenton/Royal Opera HouseFor the cast members of “La Bohème,” which ends live performances on Tuesday but can be streamed online through July 25, the pandemic has only compounded the art form’s challenges.Danielle de Niese, who plays Musetta, the femme fatale, said in an interview during rehearsals that without a pandemic it was hard enough to do “the drunken tabletop thing” — having to hop from one tabletop to another in a long, heavy gown while singing at the top of her lungs. The coronavirus, she said, also meant having “to do all of our rehearsals with a mask on, and that is a killer.”“It is incredibly challenging to sing into a material mask,” she said. “It basically kills your sound, and it feels like you’re singing into a pillow.”Ms. de Niese, a soprano, pulled out her special opera-singer mask: a protruding face covering with an extra wire that ensured it wouldn’t “go up my nostrils” at each breath. Masks were worn throughout the rehearsal period, she said, and instead of the “natural camaraderie between colleagues” and between acts, performers had to sit on strictly distanced chairs.Ms. de Niese said she was concerned about “singers who are just starting to get into it, who aren’t yet making the big bucks,” and who, struggling financially during the pandemic, had to take “a job packing boxes at Amazon.”“We need to make sure that the next generation will still put their skin in the game,” she said.The Royal Opera’s next big show is directed by Mr. Mears himself: a new production of Verdi’s “Rigoletto,” opening in the fall. In its favor during a pandemic? It doesn’t have a chorus, he pointed out.Despite the prolonged shutdown and logistical and financial headaches, Mr. Mears said there was a silver lining to the difficulty: a regained appreciation for opera.“We always thought that this was something that would always exist, and now I think there’s a tremendous sense of gratitude for the work that we are able to make,” he said. “I don’t think we’ll ever take opera for granted again, and that can only be a good thing.” More