https://zenodo.org/records/23165256?

Published October 5, 2026 | Version v1
Preprint Open

Neurodevelopmental Outcomes in COVID-19-Vaccinated Versus Unvaccinated U.S. Children: Analysis of the National Health Interview Survey, 2022–2024

Conclusions: In a direct comparison of COVID-19-vaccinated with unvaccinated children in a nationally representative U.S. sample, COVID-19 vaccination was associated with higher adjusted odds of autism, ADHD, anxiety, special-education use, and mental-health treatment. The autism association persisted across every adjustment tier; was unchanged under propensity-score balancing that removed all measured covariate imbalance and nullified the acute-care negative controls; was robust to restriction to physically healthy children; increased monotonically with dose count; was largest in the youngest exposed cohorts, including children vaccinated before the school-entry diagnostic window; and exceeded that of influenza vaccination in direct comparison. These properties satisfy the strength, consistency, biological gradient, plausibility, and coherence considerations for causal inference, and no measured confounder explains them. Because the cross-sectional design cannot order exposure and diagnosis, a global scheduled combination childhood vaccine effect on neurodevelopment cannot be evaluated. A linked birth-cohort study of toddlers before age 3 capturing co-administered vaccines, incident diagnoses, and pre-specified negative controls would be the next step in evaluating this concerning association.