• Adverse effects may be related, unrelated, or unknown in relation to a vaccine and may range from self-limited mild reactions to permanent sequelae.
  • The causal inference of any adverse effect to a vaccine is based on assessing the strength of association, temporal response, consistency and specificity of the association, and biological plausibility.
  • Safety evaluation depends on accurate reporting of adverse events during pre-licensure studies and post-licensure surveillance.