title: Vaccine safety: current systems and recent findings.
abstract: OBJECTIVE
  An understanding of vaccine safety is important for all immunization providers, who have responsibilities to identify, report, and prevent adverse events.
  
  
  RESULTS
  New analytic methods can provide more rapid information on adverse events compared with traditional observational studies. Some adverse events following vaccination are preventable. Syncope is increasingly recognized postvaccination and may be associated with severe injury or death. Both human and system factors should be addressed to prevent vaccine administration errors. Ongoing basic science and clinical research is critical to improved understanding of vaccine safety. A recent study suggests that many cases of encephalopathy following whole-cell pertussis vaccine were due to severe myoclonic epilepsy of infancy, a severe seizure disorder associated with mutations of the sodium channel gene SCN1A.
  
  
  CONCLUSIONS
  Vaccine safety requires prelicensure evaluation, postlicensure surveillance and investigation, addressing preventable adverse events, reconsideration of vaccine policy as understanding of risks and benefits changes, and ongoing research to better understand the response to vaccination and the pathogenesis of adverse events.
authors: National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop E05, Atlanta, GA 30333, USA. mew2@cdc.gov
authors: Melinda
authors: M
authors: Wharton
mesh_terms: D000075202:Contraindications; D019992:Databases as Topic; D017277:Drug Approval; D004342:Drug Hypersensitivity / Q000517:prevention & control; D006291:Health Policy; D006801:Humans; D016867:Immunocompromised Host; D008508:Medication Errors / Q000517:prevention & control; D011358:Product Surveillance, Postmarketing; D012449:Safety; D014611:Vaccination; D014612:Vaccines / Q000008:administration & dosage* / Q000009:adverse effects*; D014613:Vaccines, Attenuated
chemical_list: D014612:Vaccines; D014613:Vaccines, Attenuated