Dr.Firman Abdullah,Sp.OG / OBGYN .BLOG: MMR vaccination and autism

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HITTING THE HEADLINES

06 Feb 2008

MMR vaccination and autism

There is no link between the MMR vaccination and autism, reported eight newspapers (5 February 2008). The newspaper reports were based on a well-conducted case-control study and were generally accurate. The study findings are likely to be reliable.

On 5 February 2008, eight newspapers (1-8) reported that there is no link between the MMR vaccine and autism.
The reports were based on a study published in the Archives of Disease in Childhood (9). The study compared 98 vaccinated children aged 10-12 years with autism spectrum disorders (ASD) to two control groups (also vaccinated) comprising 52 children with special educational needs but no ASD and 90 typically developing children within the same geographical area. There was no evidence of a differential response to measles virus or the measles component of the MMR between children with ASD, with or without regression, and controls who had either one or two doses of MMR.
Six of the papers accurately report the key findings from the study and in two there is no reporting of the study results (7-8). The study appears well conducted and the conclusions are likely to be reliable. The findings of the study are in line with previous epidemiological studies showing no association between MMR vaccination and the development of autism.

Evaluation of the evidence base for measles vaccination and antibody response in autism spectrum disorders

Where does the evidence come from?

The research was conducted by Professor G Baird and colleagues from Guy's & St Thomas' NHS Foundation Trust in London and various hospitals and research institutes in the UK. The study was funded by the Department of Health, the Wellcome Trust, the National Alliance for Autism Research (NAAR) and Remedi.

What were the authors' objectives?

To test the hypothesis that measles vaccination was involved in the pathogenesis of autism spectrum disorders (ASD) as evidenced by signs of a persistent measles infection or abnormally persistent immune response in children with ASD who had been vaccinated against MMR compared with controls.

What was the nature of the evidence?

A community based case-control study was conducted of 240 children aged 10-12 years. Children with a diagnosis of ASD were identified among a cohort of 56,946 children from 12 districts in the South Thames Region of the UK. Controls with a statement of special educational needs (SEN) but no ASD diagnosis were identified from the same cohort. A second control group comprised typically developing children born at the same time and in the same area as the ASD cases. Children whose blood samples showed that they had received at least one MMR vaccination were eligible for the study.

How did participants differ on their level of exposure to the factor of interest?

A total of 235 children had received the first MMR vaccination: 98 with ASD, 52 SEN controls, and 85 typically developing controls. Stage 2 MMR vaccination was received by 106 children: 35 children with ASD, 18 SEN controls and 53 typically developing controls. Five children with no evidence of at least one MMR vaccination were excluded from the analysis. The particular factors of interest were the detection of the measles genome or measles antibody concentrations and whether these differed between the ASD group and the control groups. An additional factor of interest was whether the presence of bowel symptoms (enterocolitis) differed between the groups.

What were the findings?

No difference was detected in the distribution of measles antibody or in measles virus in ASD cases and controls whether the children had received the first, second or both MMR vaccinations. When the analysis was restricted to ASD cases with a history of regression there remained no difference between the groups. Only one child, who did not have ASD or regression, had symptoms of possible enterocolitis.

What were the authors' conclusions?

There is no association between measles vaccination and ASD. In this cohort children were less likely to receive the second MMR vaccination after diagnosis of a developmental problem.

How reliable are the conclusions?

The research was a well-conducted case-control study, the largest of its type to be undertaken, and the conclusions are likely to be reliable. ASD cases and SEN controls were located by screening a large cohort of children likely to be representative of the general population. The selection of the patients, and allocation into study groups, was based on the use of standardised tools for the diagnostic assessment of autism. Rigorous methods were used to assess both exposure to MMR vaccine and the presence of measles virus or antibodies to the virus. The typically developing control group was not obtained from a randomised selection process and through inviting participation in the study it is possible that a biased group elected to participate. The findings of the study are in line with previous epidemiological studies showing no association between MMR vaccination and the development of ASD.

Systematic reviews

Information staff at CRD searched for systematic reviews relevant to this topic. Systematic reviews are valuable sources of evidence as they locate, appraise and synthesize all available evidence on a particular topic.

There was one related systematic review identified on the Cochrane Database of Systematic Reviews (CDSR) (10) and two on the Database of Abstracts of Reviews of Effects (DARE) (11,12).

References and resources

1. The research that 'disproves MMR jab link to autism'. The Daily Mail, 5 February 2008, p4.

2. MMR and autism link is dismissed. The Times, 5 February 2008, p18.

3. MMR vaccine does not cause autism, says study. The Daily Telegraph, 5 February 2008, p7.

4. MMR links to autism dismissed by huge study. The Guardian, 5 February 2008, p1.

5. No link between the MMR jab and autism. Daily Mirror, 5 February 2008, p26.

6. Parents' anger over new 'evidence' that the MMR jab is safe. Daily Express, 5 February 2008, p17.

7. MMR jab given OK. The Sun, 5 February 2008, p21.

8. Autism 'is not linked to MMR'. The Independent, 5 February 2008, p13.

9. Baird G, Pickles A, Simonoff E [et al.]. Measles vaccination and antibody response in autism spectrum disorders. Archives of Disease in Childhood. Online publication February 5 2008 doi:10.1136/adc.2007.122937.

10. Demicheli V, Jefferson T, Rivetti A, Price D. Vaccines for measles, mumps and rubella in children. The Cochrane Database of Systematic Reviews 2005, Issue 4. Art. No.: CD004407. DOI: 10.1002/14651858.CD004407.pub2.

11. Jefferson T, Price D, Demicheli V, Bianco E, European Research Program for Improved Vaccine Safety. Unintended events following immunization with MMR: a systematic review. Vaccine 2003;21(25-26):3954-3960. [DARE Abstract]

12. Wilson K, Mills E, Ross C, McGowan J, Jadad A. Association of autistic spectrum disorder and the measles, mumps, and rubella vaccine: a systematic review of current epidemiological evidence. Archives of Pediatrics and Adolescent Medicine 2003;157(7):628-34. [DARE Abstract]