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Are childhood vaccines safe? What does the evidence show?

Last updated on April 10, 2026

The evidence for childhood vaccine safety is among the most robust in medicine, drawn from clinical trials, post-market surveillance, and studies involving tens of millions of children. No credible scientific evidence links vaccines to autism or other chronic conditions. The original study claiming a link was retracted and its author found guilty of fraud.

Evidence Summary

  • Data source: RCTs, CDC VAERS post-market surveillance, large epidemiological studies (including Danish MMR/autism study, n=650,000+)

  • Key finding: Multiple large studies across different countries find no link between MMR vaccine and autism

  • Key finding: Thimerosal was removed from childhood vaccines in 2001; autism rates continued rising afterward, disproving the thimerosal hypothesis

  • Key finding: The 1998 Wakefield study claiming an MMR-autism link was retracted and found fraudulent

  • Caveat: Some rare vaccine adverse events are real (e.g., febrile seizures, rare allergic reactions) — the question is always risk vs. benefit, and the benefit strongly dominates

Confidence: High confidence — one of the most extensively studied questions in modern medicine, with consistent findings across dozens of large independent studies.

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