A confirmed case of measles has triggered alerts after thousands attended the pop star’s May 15 MetLife Stadium show.

Health authorities in New Jersey have issued a public alert following possible measles exposure during Shakira’s concert at MetLife Stadium on Thursday, May 15. The warning comes after a confirmed case was linked to an individual who attended the show while infectious.

One case, thousands potentially at risk

In a statement released on May 20, the New Jersey Department of Health reported that the infected person was present at the stadium between 7:30 p.m. and 1:00 a.m., putting attendees at risk of contracting the highly contagious virus. Symptoms of measles can take up to 21 days to appear — in this case, as late as June 6.

“No additional cases have been identified in New Jersey at this time,” the department clarified, adding that the infected individual is not a New Jersey resident. Concertgoers are being urged to monitor for fever, rash, cough, or conjunctivitis and to seek medical attention if symptoms arise.

Shakira’s tour kicks off with a health scare

The concert marked the first of two back-to-back nights at the 50,000-seat venue. Shakira was joined by Ozuna on May 15, while Pitbull, Wyclef Jean, and Rauw Alejandro performed the following evening.

The Colombian superstar’s Las Mujeres Ya No Lloran World Tour had just launched its North American leg after record-breaking shows in Latin America earlier this year. Upcoming stops include Chicago, Boston, Miami, and Los Angeles, with the final U.S. performance set for San Francisco on June 30, before the tour continues in Mexico and Peru.

Shakira’s team has not yet released a statement regarding the exposure alert.