MMR vaccine and autism link debunked again: MMR vaccine reduces ASD risk in subgroup of girls

Summary: Another new study refutes claims of a link between the MMR vaccine and autism. The study reports no link has been found between MMR and an increased autism risk, even in children with other risk factors for ASD. Researchers also reported, in a subgroup of girls, the MMR vaccine reduced the risk of autism by between 16% and 21%. No link was found between other vaccinations, such as Hib and DTaP, and an increased risk of ASD.

Source: American College of Physicians

A nationwide cohort study of all children born in Denmark to Danish-born mothers between 1999 through 2010 concluded that the mumps, measles, and rubella (MMR) vaccine does not increase the risk of autism, does not trigger autism in susceptible children, and is not associated with clustering of autism cases following vaccination. The findings are published in Annals of Internal Medicine.

The hypothesized link between measles, mumps, rubella (MMR) vaccine and autism continues to cause concern and challenge vaccine uptake. Currently, there is a concerning increase in measles cases in Europe and the U.S., and the World Health Organization (WHO) has declared vaccine hesitancy as one of the top 10 threats to global health.

Researchers from Statens Serum Institut, Copenhagen, Denmark used a Danish population registry to evaluate whether the MMR vaccine increases the risk for autism in children, subgroups of children, or time periods after vaccination. Of the 657,461 children included in the analysis over a decade of follow-up, 6,517 were diagnosed with autism. Comparing MMR-vaccinated with MMR-unvaccinated children yielded a fully adjusted autism hazard ratio of 0.93.

kids are playing on a swing in this image

Additionally, in the subgroup analysis, girls who received the MMR vaccination had a 16% to 21% reduced risk of autism. The image is in the public domain.

Similarly, no increased risk for autism after MMR vaccination was consistently observed in subgroups of children defined according to sibling history of autism, autism risk factors (based on a disease risk score) or other childhood vaccinations, or during specified time periods after vaccination.

Additionally, in the subgroup analysis, girls who received the MMR vaccination had a 16% to 21% reduced risk of autism.

The study also evaluated whether other childhood vaccinations, such as DTaP and Hib, increased autism risks. Similar to the MMR finding, researchers found no evidence to link these vaccinations to an increased risk of ASD (Autism Spectrum Disorder) diagnosis, even in the subgroup of children with genetic risk factors for autism.

According to the researchers, this study adds to previous studies through significant additional statistical power and addresses questions about susceptible subgroups and autism clustering.

About this neuroscience research article

Source:
American College of Physicians
Media Contacts:
Lauren Evans – American College of Physicians
Image Source:
The image is in the public domain.

Original Research: Open access
“Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study”. Anders Hviid, DrMedSci; Jørgen Vinsløv Hansen, PhD; Morten Frisch, DrMedSci; Mads Melbye, DrMedSci. Annals of Internal Medicine April 16 2019. doi:10.7326/M18-2101

Abstract

Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study

Background:
The hypothesized link between the measles, mumps, rubella (MMR) vaccine and autism continues to cause concern and challenge vaccine uptake.

Objective:
To evaluate whether the MMR vaccine increases the risk for autism in children, subgroups of children, or time periods after vaccination.

Design:
Nationwide cohort study.

Setting:
Denmark.

Participants:
657,461 children born in Denmark from 1999 through 31 December 2010, with follow-up from 1 year of age and through 31 August 2013.

Measurements:
Danish population registries were used to link information on MMR vaccination, autism diagnoses, other childhood vaccines, sibling history of autism, and autism risk factors to children in the cohort. Survival analysis of the time to autism diagnosis with Cox proportional hazards regression was used to estimate hazard ratios of autism according to MMR vaccination status, with adjustment for age, birth year, sex, other childhood vaccines, sibling history of autism, and autism risk factors (based on a disease risk score).

Results:
During 5,025,754 person-years of follow-up, 6517 children were diagnosed with autism (incidence rate, 129.7 per 100 000 person-years). Comparing MMR-vaccinated with MMR-unvaccinated children yielded a fully adjusted autism hazard ratio of 0.93 (95% CI, 0.85 to 1.02). Similarly, no increased risk for autism after MMR vaccination was consistently observed in subgroups of children defined according to sibling history of autism, autism risk factors (based on a disease risk score) or other childhood vaccinations, or during specified time periods after vaccination.

Limitation:
No individual medical charts were reviewed.

Conclusion:
The study strongly supports that MMR vaccination does not increase the risk for autism, does not trigger autism in susceptible children, and is not associated with clustering of autism cases after vaccination. It adds to previous studies through significant additional statistical power and by addressing hypotheses of susceptible subgroups and clustering of cases.

Primary Funding Source:
Novo Nordisk Foundation and Danish Ministry of Health.

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