MMR is a live attenuated vaccine. Indian children show almost 90% seroconversion against measles and rubella and 90% against mumps. Several adverse effects have been reported. Epidemiological studies do not support a causative link between MMR and autism, IBD or GBS. There is an association between the Urabe strain of mumps vaccine and viral meningitis. Vaccine associated thrombocytopenia has been reported. Severe hypersensitivity reactions occur, mainly due to the gelatin component. Outbreaks of measles occur in areas of high measles vaccine coverage, when susceptible individuals accumulate. A second dose is given mainly to vaccinate those who missed the first dose or had primary vaccine failure, rather than to boost waning antibody levels. The possibility or eradication of mumps with a second dose of mumps vaccine is being considered.