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Pediatrics52 papers

Encephalitis caused by measles vaccine

Last edited: 4/10/2026

Overview

Encephalitis is a rare but serious adverse event that can occur following measles-containing vaccines (MCV) 1. While the risk is exceedingly low, it is a concern for vaccine hesitancy 1.

Diagnosis

Management

Special Populations

Key Recommendations

  • Measles-containing vaccines (MCV) are generally well-tolerated in infants under 12 months of age, with common adverse events including injection site reactions, fever, rash, gastrointestinal symptoms, respiratory tract symptoms, conjunctivitis, and general malaise 1.
  • The frequency of any adverse event following MCV1 in infants under 12 months is generally less than 10 percent 1.
  • A placebo-controlled trial showed no difference in adverse events between infants receiving MCV1 and those receiving a placebo injection 1.
  • References

    1 Vittrup DM, Charabi S, Jensen A, Stensballe LG. A systematic review and meta-analysis of adverse events following measles-containing vaccines in infants less than 12 months of age. Vaccine 2025. link

    Original source

    1. [1]

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