The MMR vaccine is a combination vaccine that protects against three contagious diseases: measles, mumps, and rubella. It is typically given to children in two doses, the first around 12-15 months of age and the second between 4-6 years. This vaccine helps prevent serious health complications associated with these diseases, such as pneumonia and brain swelling. Getting the MMR vaccine is important for public health, as it helps maintain herd immunity. When a large portion of the population is vaccinated, it reduces the spread of these diseases, protecting those who cannot be vaccinated, such as infants and individuals with certain medical conditions.