Immunization Science

MMR Vaccination and Pervasive Developmental Disorders

The article

MMR vaccination and pervasive developmental disorders: a case-control study. Smeeth L, Cook C, Fombonne E, Heavey L, Rodrigues LC, Smith PG, and Hall AJ. The Lancet 2004;364(9438):963-969.

The question

Is vaccination with the measles-mumps-rubella (MMR) vaccine associated with an increased risk of autism or other pervasive developmental disorders (PDD)?

The study

This case-control study included all people who were born after 1972 and who were registered in the General Practice Research Database (GPRD) in the United Kingdom between June 1, 1987 and December 31, 2001. This ensured that all recipients of MMR were included.

The researchers identified 1,294 cases that had the first diagnosis of autism or other PDD between 1987 and 2001. The researchers compared these cases with 4,469 control persons with no diagnosis of PDD who were matched by year of birth, sex and general practice.

Separately (with the case control status concealed), the investigators determined the immunization status of all the children.

The findings

About three quarters of the cases were classified as having autism and the remainder was classified as having another PDD.

Cases were less likely to have received MMR vaccination before the first date of diagnosis of autism or PDD than were controls. The results were similar when reanalyzed for different ages at immunization, duration of time in the practice, age on joining the particular practice, whether the diagnosis was autism or other PDD, and other possible confounding variables.

The relevance/bottom line

MMR vaccination was not associated with an increased risk of subsequently being diagnosed with autism or other PDD.

NNii’s comment

Measles, rubella and mumps are serious diseases that can be prevented by immunization. There is no evidence that MMR vaccine causes autism or PDD.