The Importance of MMR Immunization in the United States.

Despite the established safety and efficacy of the measles-mumps-rubella vaccine after almost 50 years of widespread use, the United States is encountering higher levels of measles and mumps disease than has occurred for years. Return of disease threatens the health of those who remain unimmunized by choice as well as those who are immunized appropriately but experience loss of vaccine-induced immunity. The solution to continued threats of illness caused by these untreatable but readily preventable diseases is compliance with recommendations for administration of the measles-mumps-rubella vaccine. Here we examine trends in the epidemiology of measles, mumps, and rubella in recent years and consider the consequences of loss of protective immunity within our country.