The announcement comes days after a Broadway usher tested positive for the coronavirus.

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Broadway is suspending all of its shows for a month after New York Gov. Andrew Cuomo on Thursday announced a ban of all gatherings of more than 500 people. The suspension on Broadway was to go into effect at 5 p.m. Thursday, 24 hours before Cuomo's ban is enforced. Cuomo acknowledged during a news conference that it only gave the Broadway industry several hours, "but we've already been talking to the Broadway theaters, and they're aware we're going to be doing this, so they have notice." On Tuesday, an usher who worked two shows tested positive for the coronavirus. The unidentified usher, who is now quarantined, most recently worked last week at performances of Who's Afraid of Virginia Woolf? The week before that he worked two performances of Six, a musical about the wives of Henry VIII. The Shubert Organization and the Nederlander Organization, which each own one of the theaters, announced the diagnosis in a statement Wednesday night. "Immediately upon learning of the positive test, both organizations began taking every step necessary to ensure the safety of our audiences, performers, crew, and building staff," representatives said in the joint statement. Both organizations said the theaters were deep-cleaned and that they were "closely following all protocols related to containment and prevention," including informing all employees who may have been exposed and urging all high-risk audience members to "monitor their health diligently." But the shows still went on Wednesday night and the theaters did not rush to close due to the virus — despite experts recommending "social distancing," or avoiding large crowds, to stop the spread of the virus. Ticket holders were, however, permitted to exchange their tickets for ones at a later date. In fact, as late as Thursday, several shows — including Who's Afraid of Virginia Woolf? — were offering $50 discount tickets to keep crowds coming as more people avoid large public gatherings. To Kill a Mockingbird, West Side Story, The Lehman Trilogy, and The Book of Mormon, all of which are produced by Broadway producer Scott Rudin, were also offering the cheap seats. “As long as New York City is open for business, its beating heart remains the Broadway stage," Rudin told Deadline. "This is an unprecedented opportunity for everyone to see a show that they otherwise might not have had easy and affordable access to. I can’t pretend that great theater is the panacea we’ve been waiting for, but in the meantime I think we could all use a few hours away from the evening news.”

Vincent Racaniello, a professor of microbiology at Columbia University, told BuzzFeed News it was crucial Broadway close in order to prevent people from catching the coronavirus.

"There is no question that Broadway shows should be closed," Racaniello said. "Any large gatherings of people, especially here in NYC where we know the virus is circulating, need to stop." The reason for drastic measures like fully shutting down shows is not because "the virus is particularly lethal," he added. "The problem is that if 1% of infected people need hospitalization, then we will rapidly overwhelm the health care system here in the city, which has limited capacity," he said. So, if an outbreak occurs at a Broadway theater, which has hundreds of seats, the results could be catastrophic when it comes to having enough resources and health care workers to care for the ill. "This is what happened in Wuhan, Italy, and Iran," Racaniello said. "We are so unprepared for this outbreak, mainly because this country's leaders are denying its existence or severity." A few miles north of Broadway, a containment zone has been established in the New York City suburb of New Rochelle — the first such designation in the US. Broadway star Stephanie J. Block, who won a Tony last year for her performance in The Cher Show, was among those urging the theaters to close.

Hard to imagine, yes. Harder to imagine what NYC becomes if we don’t. https://t.co/5lsMEKMoNG

But many people who work in the theaters — including ushers and actors — have few other sources of income. Even while the theaters were open, precautions were set in place at many of them. The Broadway League, the industry's trade association, discouraged the common practice of actors greeting fans at the stage door for pictures and autographs.

"As an added precaution, we are highly recommending that all stage door activities be eliminated for the time being," the league said in a statement. Many shows announced a suspension of the stage door tradition on social media.

You're all true blue and we love seeing you waving through our window each night. However, in an effort to keep everyone safe and healthy, we’re joining our Broadway neighbors and temporarily suspending stage door greetings. Thanks for your understanding.

We have good news and we have other news! The good news is: stripes are gonna be huge this spring. The other news is: beginning tonight, our cast will not be doing the whole “stage door” thing after the performance.

Every Broadway theater was equipped with hand sanitizer dispensers in the lobby, and cleaning and disinfecting has "significantly increased" in public areas and backstage, the trade association said.

"Anyone who is experiencing cold or flu symptoms, or who is not feeling well, is encouraged to stay home and contact the point of purchase for more information about ticket exchanges and policies," it added. Before the shows were canceled, it was unclear whether refunds would be made available to those who wished to sit performances out, as tickets are usually not refundable unless the event is canceled or rescheduled. On Twitter, many people had been complaining of "radio silence" and refusals of refunds from Ticketmaster and Telecharge. One person on Reddit reported the ticketing sites offered full refunds upon hearing the person was self-quarantining. BuzzFeed News has reached out to Ticketmaster and Telecharge regarding their refund policies during the coronavirus outbreak.

JUST NOW: @NYCMayor Bill de Blasio tells me a decision on Broadway shows coming in next 48 hours... "Is there a way to reduce the capacity, reduce the number of people? If we cannot strike that balance of course you can go to closure." @NewDay