It is the first known show cancellation due to Covid-19 since Broadway began reopening earlier this month after shutting down in March 2020 due to the pandemic. “Through our rigorous testing protocols, breakthrough COVID-19 cases have been detected within the company of Aladdin at The New Amsterdam Theatre,” the show said Wednesday in a tweet. “We will continue to provide support to the affected Aladdin company members as they recover.” Show runners didn’t say how many Covid-19 cases were detected, noting they will provide more information Thursday regarding future performances. Broadway is big business for New York’s economy — an estimated 97,000 people are employed by shows. And when Covid-19 first swept across the US, it made New York City one of the first virus hotspots, forcing theaters to shutter for about 18 months. This month, theaters began gradually reopening, raising their curtains with health measures in place to help protect against the spread of coronavirus. All of New York’s 41 Broadway theaters require eligible audiences, crews, performers and other staff to be vaccinated against Covid-19, according to the Broadway League’s policy. Children under 12 and those unvaccinated due to health conditions or religious reasons must provide a negative Covid-19 test to be granted entry. Audience members are also required to be masked inside theaters.Breakthrough cases occur when someone tests positive for Covid-19 at least 14 days after they have been fully vaccinated, according to the US Centers for Disease Control and Prevention (CDC). Such infections can cause disease with symptoms but some vaccinated people who become infected with Covid-19 show no symptoms at all. Research has shown that if people become infected after vaccination, typically they get a milder case.New York is one of the most vaccinated states in the nation, with more than 63% of its residents fully vaccinated against Covid-19, CDC data showed Wednesday. CNN’s Carolyn Sung and Marianne Garvey contributed to this report.