Reassuring Findings About Influenza Vaccine and Autism Spectrum Disorder

To examine the long-term safety of maternal influenza immunization on pediatric health, researchers in Sweden assessed risk for autism spectrum disorder (ASD) and its most severe form, autism disorder (AD), in a nationwide cohort of almost 40,000 women who delivered between October 2009 and September 2010. About 35% of these pregnant women received p2009 H1N1 vaccine; mean follow-up in their children was 6.7 years.

In both adjusted and unadjusted analyses, neither ASD nor AD was increased in children of vaccinated compared with unvaccinated women. Restricting the analysis to women who were immunized during the first trimester did not affect the results. Because of the large size of this study, the authors could rule out a relative increase i…