Autism is not associated with the MMR vaccine. The MMR vaccine does not increase autism risk. To put it in plain language: the MMR vaccine does not cause autism.
Just in case the message gets lost in this discussion, I figured I’d put it plainly at the start.
A study out today compares autism rates and the use of the MMR vaccine. In specific, the researchers looked at children with an older sibling. In this way they could look at kids in a high risk group, those who had an older sibling who is autistic. The authors also looked at kids who had older siblings who are not autistic. In the end the authors found “receipt of the MMR vaccine was not associated with increased risk of ASD, regardless of whether older siblings had ASD”.
To put it simply, kids who got the MMR vaccine were not more likely to be autistic. It doesn’t matter if their older siblings were autistic or not. So, “high risk” or not, the MMR vaccine doesn’t increase autism risk.
Another way to say it, parents who skipped the MMR vaccine did nothing to prevent autism in their younger kids. Nothing. They did leave their younger kids vulnerable to measles infection.
Here’s the abstract.
Despite research showing no link between the measles-mumps-rubella (MMR) vaccine and autism spectrum disorders (ASD), beliefs that the vaccine causes autism persist, leading to lower vaccination levels. Parents who already have a child with ASD may be especially wary of vaccinations.
To report ASD occurrence by MMR vaccine status in a large sample of US children who have older siblings with and without ASD.
DESIGN, SETTING, AND PARTICIPANTS:
A retrospective cohort study using an administrative claims database associated with a large commercial health plan. Participants included children continuously enrolled in the health plan from birth to at least 5 years of age during 2001-2012 who also had an older sibling continuously enrolled for at least 6 months between 1997 and 2012.
MMR vaccine receipt (0, 1, 2 doses) between birth and 5 years of age.
MAIN OUTCOMES AND MEASURES:
ASD status defined as 2 claims with a diagnosis code in any position for autistic disorder or other specified pervasive developmental disorder (PDD) including Asperger syndrome, or unspecified PDD (International Classification of Diseases, Ninth Revision, Clinical Modification 299.0x, 299.8x, 299.9x).
Of 95 727 children with older siblings, 994 (1.04%) were diagnosed with ASD and 1929 (2.01%) had an older sibling with ASD. Of those with older siblings with ASD, 134 (6.9%) had ASD, vs 860 (0.9%) children with unaffected siblings (P < .001). MMR vaccination rates (≥1 dose) were 84% (n = 78 564) at age 2 years and 92% (n = 86 063) at age 5 years for children with unaffected older siblings, vs 73% (n = 1409) at age 2 years and 86% (n = 1660) at age 5 years for children with affected siblings. MMR vaccine receipt was not associated with an increased risk of ASD at any age. For children with older siblings with ASD, at age 2, the adjusted relative risk (RR) of ASD for 1 dose of MMR vaccine vs no vaccine was 0.76 (95% CI, 0.49-1.18; P = .22), and at age 5, the RR of ASD for 2 doses compared with no vaccine was 0.56 (95% CI, 0.31-1.01; P = .052). For children whose older siblings did not have ASD, at age 2, the adjusted RR of ASD for 1 dose was 0.91 (95% CI, 0.67-1.20; P = .50) and at age 5, the RR of ASD for 2 doses was 1.12 (95% CI, 0.78-1.59; P = .55).
CONCLUSIONS AND RELEVANCE:
In this large sample of privately insured children with older siblings, receipt of the MMR vaccine was not associated with increased risk of ASD, regardless of whether older siblings had ASD. These findings indicate no harmful association between MMR vaccine receipt and ASD even among children already at higher risk for ASD.
By Matt Carey