Read our Privacy noticeLos Angeles County health officials have issued a public health alert after someone with an infectious case of measles visited Universal Studios Hollywood last month, potentially exposing numerous park-goers to the highly contagious virus. While those who have previously contracted measles or received the recommended measles-mumps-rubella (MMR) vaccine are generally protected, health officials still recommend vigilance for symptoms. "The MMR vaccine is the safest and most reliable way to prevent measles and protect yourself, your family and your community." According to the department, two doses of the MMR vaccine are about 97 percent effective at preventing the disease. As of July 31, 2,371 measles cases have been reported nationwide this year, according to county health officials.