The MR vaccine is a vaccine that protects against measles and rubella, two highly contagious viral diseases. The vaccine is a live attenuated vaccine, meaning that it contains weakened versions of the viruses that cause measles and rubella. The MR vaccine is highly effective and has been used for over 40 years in many countries across the world. The vaccine is safe and well-tolerated, with side effects being mostly mild and transient, such as slight pain and tenderness at the site of injection, mild fever, and local lymphadenopathy. The MR vaccine is recommended for infants, children, adolescents, and adults. In some cases, public health authorities might recommend an additional dose of the MR vaccine during a measles or rubella outbreak. The MR vaccine is an important tool in preventing the spread of measles and rubella, which can cause serious health complications and even death.