New Jersey health officials issued a warning about a potential measles exposure during the Shakira concert at MetLife Stadium.

According to the New Jersey Department of Health, concertgoers at a recent Shakira concert held in MetLife Stadium may have been exposed to measles. This comes after the recent discovery that a fan from outside the state attended the concert while infected with the disease on May 15.

The NJ Health Department is warning the 55,000 fans who attended the Shakira concert at MetLife stadium in East Rutherford last week that they may have been exposed to measles.