Self-reported vaccine hesitancy and refusal among parents of children with autism spectrum disorder and other developmental delays: a cross-sectional study.

UNLABELLED: Due to the spread of misinformation that some vaccines cause autism spectrum disorder (ASD), many parents report changes in their vaccination behavior following a diagnosis of ASD, putting their children at increased risk for preventable diseases. Our study aimed to determine the rate of vaccination-related concerns and refusal behaviors in parents of children with ASD and non-autistic developmental delays (non-ASD-DD) and to examine factors potentially associated with vaccine hesitancy and refusal. In our study, a questionnaire was distributed to all parents of children diagnosed with ASD and non-ASD-DD who attended outpatient check-ups over 3 months at the Child Psychiatry Clinic of the two large hospitals. Participants completed a structured questionnaire assessing self-reported vaccination behaviors before and after diagnosis, as well as separate Likert-scale items evaluating vaccine-related beliefs and attitudes. No parents declined participation, and all 154 eligible parents were included in the study. Among the respondents, 87.7% were mothers. The most common diagnoses were intellectual disability (41.6%) and ASD (31.2%). Reported vaccine refusal increased from 3.9% before diagnosis to 9.7% after diagnosis (p = 0.012). The main reason cited for hesitancy or refusal was the belief that vaccines had caused their child's neurodevelopmental condition. No independent associations were found between post-diagnosis vaccine hesitancy/refusal and parental education, income, source of vaccine information, or depression/anxiety scores. However, 88.3% of participants disagreed or strongly disagreed with the statement that vaccines cause ASD or developmental disorders.

CONCLUSIONS: Parental concerns about vaccines persist after a diagnosis of neurodevelopmental disorders. Tailored education and communication strategies are essential to support informed vaccine decision-making in these families and to prevent refusal for both diagnosed children and their siblings.

WHAT'S KNOWN: • Persistent misinformation linking childhood vaccines-particularly the MMR vaccine-to autism spectrum disorder continues to influence parental attitudes toward vaccination. • Parents of children with ASD have been shown to exhibit higher rates of vaccine hesitancy, especially regarding vaccination of younger siblings.

WHAT IS NEW: • Vaccine hesitancy and refusal were more frequently reported after the diagnosis of not only autism spectrum disorder but also other developmental delays, including intellectual disability and speech delay. • Although concerns about vaccines causing developmental disorders were common, vaccine refusal remained relatively uncommon and no independent predictors of post-diagnosis hesitancy or refusal were identified, highlighting the complex nature of parental vaccination decisions.