The clinical features and morbidity of a total of 697 cases of syncope after vaccination reported to the national Vaccine Adverse Reporting System were analyzed at the Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, Md. The vaccines implicated included measles-mumps-rubella (33%), oral polio (15%), tetanus-diphtheria, adult (15%), D.T.P. (12%), hepatitis B (10%), influenza (4%), H influenza B (3%), D.T., pediatric (2%), D.T. acellular pertussis (2%), and typhoid (1%). Of 511 syncopes occurring within 1 hour of vaccination, 63% were within 5 min and 98% within 30 min. Approximately 25% of attacks were complicated by tonic or clonic movements, and 10% of the total required hospitalization. Head injuries with skull fracture, intracranial bleeding, or cerebral contusion resulted from syncope-induced falls in 6 individuals, 12 to 28 years of age, and 3 required surgery, with neurologic deficits in 2. 
COMMENT. Vaccinators should advise patients to sit for at least 15 minutes after immunization, and particularly following MMP vaccine. Those complaining of light-headedness should be checked for hypotension and bradycardia. A 25% incidence of convulsive movements reported in association with these post-immunization vasovagal attacks is of interest. Seizures in association with syncope following blood donation are not uncommon, and are rarely found to represent an epileptic event. Auras associated with syncope have some similarity to those preceeding epileptic seizures, but in contrast to epilepsy, syncopal auras lack localizing significance and may be less complex. Aura phenomena during syncope were studied in 60 patients, mainly adults, with cardiac and 40 with vasovagal syncopes at the University Clinic, Innsbruck, Austria . Auras in 93% were mostly epigastric, vertiginous, visual, or somatosensory experiences, more detailed in the vasovagal group. Syncope-related auras were distinguished from epileptic phenomena by their lack of symptoms such as tastes, smells, and deja vu.