In the 1990’s, concern spread about the safety of the MMR vaccine due to supposed evidence that it contributed to the development of autism. A study looking at GP records in the Clinical Practice Research Datalink helped to conclusively show that there is no evidence of a link between the MMR (measles, mumps and rubella) vaccination and autism.

Why was this work needed?

Measles, mumps and rubella are highly infectious conditions that can have serious complications, particularly in children, including meningitis, swelling of the brain and deafness. Since a vaccine was introduced in the late 1990s, it has been rare for children to develop these conditions.

However, in 1998, a fraudulent research paper was published claiming a link between the MMR vaccine and autism. The paper was subsequently withdrawn by the Lancet and its author was struck off the UK Medical Register. Publication of the article led to a fall in the uptake of the vaccine, increasing the risk of an outbreak of these highly infectious, serious conditions.

What happened?

Researchers compared the GP records of people diagnosed with autism between 1987 and 2001 with records of people from the same GP practice, with the same age and sex who did not have autism. By looking closely at the levels of vaccination in the two groups, they found no evidence of a link between autism and the MMR vaccine.

What were the benefits?

This study clearly showed that there is no reason to believe there is a link between the MMR vaccine and autism in children. This has been key to rebuilding public confidence in the safety of the vaccine and ensuring that children are vaccinated against these dangerous, infectious diseases.

What type of data was involved?

This study used the Clinical Practice Research Datalink (CPRD), which was called the General Practice Research Datalink (GPRD) at the time. GPRD contained information including records of vaccinations and diagnoses of autism.

GP practices opt to be involved in the CPRD, but no identifying data such as name or address is shared. Because patients are not identifiable, these GPs don’t need to acquire consent to share the data with CPRD. CPRD data can only be used for public health research, and only verified researchers receive access.

Under the current opt-out policy, patients can opt-out of having their data used for research, which means their GP could not share their data with CPRD. However, it is not possible to find out whether your GP has chosen to share data with CPRD.

Who funded and collaborated on this work?

The UK Medical Research Council (MRC) funded this study.

Where can I go for more information?

MMR vaccination and pervasive developmental disorders: a case-control study