At 12 months of age, the immunization for Measles (Rubeola), Mumps and Rubella is given. The MMR is repeated at three to five years of age. Measles is a very contagious viral infection, which causes the child to be extremely sick with high fever, generalized red rash on the body, red watery eyes, marked runny nose, and deep cough. It is often associated with such complications as ear infections, bronchitis, pneumonia and encephalitis. Approximately 3% of the children who contract natural measles will have permanent damage and occasionally death.

Mumps is a mild viral infection which causes swelling of the glands in front of the ears and fever. It can cause swelling of the testicles or ovaries and sometimes causes mild encephalitis. Though usually a mild disease, death has been reported.

German measles (Rubella) is a mild viral illness of approximately three days duration. Its greatest danger is to the developing fetus during the first three months of pregnancy because it can cause severe congenital defects (congenital rubella syndrome).

The MMR vaccine has few side effects. Occasionally, ten to twelve days following injection, a mild Measles-like illness will develop, characterized by generalized rash, sometimes fever, or nasal discharge. This generally lasts two to three days and the children are not contagious. The only treatment required is rest and measures to control the fever.

The Rubella vaccine will rarely cause mild, transient joint pain in the arm that received the injection. No treatment is required. There are no known side effects from Mumps vaccine.

The MMR vaccine has been the most studied and scrutinized vaccine because some people wrongly believe it causes Autism. To date, no study has ever shown that the MMR vaccine is a cause or trigger for Autism.