177. Safety of Measles and Pertussis-containing Vaccines in School-age Children Previously Diagnosed with Autism Spectrum Disorders

Background Some parents, especially those of children with autism spectrum disorders (ASD), are uncertain about the safety of childhood immunization. We compared rates of fever, febrile seizure and emergency room (ER) visits following measles and pertussis-containing vaccines recommended between ages 4–6 years among children with and without ASD. Methods The study included children who were born between 1995–2012, aged 4–7 years at vaccination, and members of six integrated healthcare delivery systems within the Vaccine Safety Datalink. Children with ASD were defined based on receipt of two separate International Classification of Diseases (ICD)-9 or 10 codes. Outcomes (fever, febrile seizures, and ER visits) were identified in electronic health records. To minimize confounding by unmeasured factors related both to avoidance of vaccination and to outcomes of interest, we compared rates of each outcome between children with and without ASD, in risk and control intervals, by estimating the difference-in-differences on a log scale (i.e. the ratio of rate ratios) using logistic regressions. We also conducted risk interval analyses comparing rates of outcomes in risk intervals and control intervals within each group. Results The study included 14,947 children with ASD and 1,650,041 children without ASD. After measles or pertussis-containing vaccination, there were no differences in association between the two groups for fever or ER visits (Table). There were no febrile seizures identified among children with ASD. Within the ASD group, rates of fever, seizure or ER visits did not differ significantly between the risk and control intervals after vaccination. However, among the non-ASD group, measles and pertussis-containing vaccines were associated with higher rates of fever and seizure in risk intervals compared to controls intervals. Pertussis-containing vaccines were associated with increased risk of ER visits in risk interval compared to control interval (Table). Conclusion We found no difference in the risk of fever, and ER visits comparing children with autism to children without autism after measles or pertussis-containing vaccines. The study provides some reassurance that these vaccines are not less safe in children with ASD. Disclosures Lei Qian, PhD, GlaxoSmithKlein (Research Grant or Support) Nicola P. Klein, MD, PhD, GSK group of companies (Research Grant or Support)Merck (Grant/Research Support)Pfizer (Grant/Research Support)Protein Science (now SP) (Grant/Research Support)Sanofi Pasteur (Grant/Research Support)