A new study published this week in JAMA, “Autism Occurrence by MMR Vaccine Status Among US Children With Older Siblings With and Without Autism”, puts one more nail in the claim that the MMR is associated with autism.
You may wonder why, after years and multiple studies showing no association between the measles-mumps-rubella vaccine (MMR) and autism spectrum disorder (ASD) there would even be a need for such a study. The authors explain:
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.
The study is a retrospective cohort study involving 95,727 children with older siblings. They looked at whether or not the older sibling had a diagnosis of ASD, whether or not they were vaccinated with MMR, and whether or not they themselves developed ASD. They found:
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).