A measles exposure could happen whenever, wherever. Thousands of concertgoers may have come in contact with the virus at a Shakira show at the MetLife Stadium last Thursday, according to an alert from the New Jersey Department of Health this week.

Videos posted to social media showed tens of thousands of people in attendance at the concert. It is one of dozens of stops on Shakira’s "Las Mujeres Ya No Lloran" world tour, a reference to the singer’s twelfth studio album. The stadium can hold around 50,000 people for most concerts, according to its website.

Fans at Shakira’s MetLife possibly exposed to the world’s most infectious disease amid declining US vaccination rates.