Post Vaccination Syncope: Follow up Survey of Reports to Vaccine Adverse Event Reporting System (VAERS)

Background: Post-vaccination syncope is most common in adolescents and young adults and can result in traumatic injury. There was a nearly six-fold increase in the number of syncope events reported to VAERS in 2008 (n=821) in comparison to 2006 (n=146). Current guidelines recommend that vaccine providers strongly consider observing patients for 15 minutes after they are vaccinated.

Objectives:   We surveyed VAERS reporters to collect information about circumstances under which post-vaccination syncope cases occurred, and potential preventive measures considered by providers.  

Methods: We conducted phone interviews with a convenience sample of reporters to VAERS. We performed an automated search for cases coded as “syncope” or “syncope vasovagal” submitted to VAERS between 1/1/09 and 8/31/09, excluding manufacturer reports. Cases of all ages and genders following any vaccines and with loss of consciousness within 1 hour from immunization were eligible. Reporters 18 years and older were interviewed.

 

Results: In this analysis, 114 cases were identified. We completed interviews with all 114 reporters of these cases; 111 of whom were immunization providers. Ninety-two syncope cases were females and 21 males with a mean age 17 years. In 68 cases (60%), syncope occurred within 5 minutes following immunization and in 12 cases (20%) the onset time was 15 minutes or longer. Tonic clonic movements associated with syncope were observed in 36 cases (32%). Falls with injury were reported in 31 persons (27%) and an additional 3 reported long-term sequela. Persons experienced syncope in the exam room, while walking to the waiting area, signing out, or in the parking lot. Eighty-one cases (71%) experienced loss of consciousness without injury. In 44 (40%) of the immunization settings vaccinees were asked to wait after the shot; in 13 settings the recommended waiting time was less than 15 minutes.    

Conclusions: Immunization providers need to become more cognizant of preventing injuries associated with post-vaccination syncope.