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Vaccination Patterns in Children After Autism Spectrum Disorder Diagnosis and in Their Younger Siblings
Ousseny Zerbo1, Sharareh Modaressi1, Kristin Goddard1
1Kaiser Permanente Vaccine Study Center, Oakland, California.
Insights
Children with autism spectrum disorder (ASD) and their younger siblings are less likely to receive recommended vaccines. This increases their risk for vaccine-preventable diseases.
Area of Science:
- Pediatric Health
- Immunization
- Neurodevelopmental Disorders
Background:
- Declining vaccination rates are a growing public health concern.
- The impact of declining immunization rates on children with autism spectrum disorder (ASD) and their siblings is not well understood.
Purpose of the Study:
- To determine if children diagnosed with ASD receive recommended vaccines.
- To compare vaccination rates of younger siblings of children with ASD to those without ASD.
Main Methods:
- Retrospective matched cohort study utilizing data from 6 integrated health care delivery systems.
- Inclusion of children with ASD and their younger siblings, alongside control groups, born between 1995 and 2014.
- Analysis of vaccination status against Advisory Committee on Immunization Practices (ACIP) recommendations up to age 12.
Main Results:
- Children with ASD were significantly less likely to be fully vaccinated between ages 4-6 compared to children without ASD (aRR, 0.87).
- Younger siblings of children with ASD exhibited lower vaccination rates across all age categories compared to siblings of children without ASD.
- Parents of children with ASD were more prone to vaccine refusal or limiting vaccine doses for younger siblings.
Conclusions:
- Children with ASD and their younger siblings are undervaccinated compared to the general population.
- This under-vaccination places these children at a higher risk for preventable infectious diseases.
- Public health strategies should address vaccination gaps in families with children with ASD.
Importance:
In recent years, rates of vaccination have been declining. Whether this phenomenon disproportionately affects children with autism spectrum disorder (ASD) or their younger siblings is unknown.
Objectives:
To investigate if children after receiving an ASD diagnosis obtain their remaining scheduled vaccines according to the Advisory Committee on Immunization Practices (ACIP) recommendations and to compare the vaccination patterns of younger siblings of children with ASD with the vaccination patterns of younger siblings of children without ASD.
Design, Setting, And Participants:
This investigation was a retrospective matched cohort study. The setting was 6 integrated health care delivery systems across the United States within the Vaccine Safety Datalink. Participants were children born between January 1, 1995, and September 30, 2010, and their younger siblings born between January 1, 1997, and September 30, 2014. The end of follow-up was September 30, 2015.
Exposures:
Recommended childhood vaccines between ages 1 month and 12 years.
Main Outcome And Measure:
The proportion of children who received all of their vaccine doses according to ACIP recommendations.
Results:
The study included 3729 children with ASD (676 [18.1%] female), 592 907 children without ASD, and their respective younger siblings. Among children without ASD, 250 193 (42.2%) were female. For vaccines recommended between ages 4 and 6 years, children with ASD were significantly less likely to be fully vaccinated compared with children without ASD (adjusted rate ratio, 0.87; 95% CI, 0.85-0.88). Within each age category, vaccination rates were significantly lower among younger siblings of children with ASD compared with younger siblings of children without ASD. The adjusted rate ratios varied from 0.86 for siblings younger than 1 year to 0.96 for those 11 to 12 years old. Parents who had a child with ASD were more likely to refuse at least 1 recommended vaccine for that child's younger sibling and to limit the number of vaccines administered during the younger sibling's first year of life.
Conclusions And Relevance:
Children with ASD and their younger siblings were undervaccinated compared with the general population. The results of this study suggest that children with ASD and their younger siblings are at increased risk of vaccine-preventable diseases.
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