Learning Objectives for this Presentation:
By the end of the presentation participants will be able to describe trends in and potential risk factors for post-vaccination syncope, and understand recommended prevention strategies.

Background:
Syncope has been reported after vaccination, most commonly among adolescents and young adults. Rarely, serious injury has resulted. The Advisory Committee on Immunization Practices (ACIP) has recommendations to prevent secondary injuries from post-vaccination syncope.

Objectives:
To characterize post-vaccination syncope during January 1, 2005–July 31, 2007 using data from the Vaccine Adverse Event Reporting System (VAERS).

Methods:
We reviewed VAERS data for syncope reports with onset <24 hours following vaccination in vaccinees aged ≥5 years during January 1, 2002–December 24, 2004 and January 1, 2005–July 31, 2007. Patient characteristics, including age, sex, and vaccine type administered, were analyzed. Reports involving injuries during January 1, 2005–July 31, 2007 were further clinically reviewed.

Results:
VAERS received 463 reports of post-vaccination syncope during January 1, 2005–July 31, 2007, compared with 203 syncope reports received during January 1, 2002–December 31, 2004. Females aged 11–18 years (49%) and non-serious events (93%) contributed most to the increase. In 292 (63%) reports, syncope was associated with at least one of the three adolescent vaccines: meningococcal conjugate vaccine (MCV4), tetanus-diphtheria-pertussis vaccine (Tdap), and human papillomavirus vaccine (HPV). Forty-one (9%) syncope events were complicated with secondary injuries: 31 (76%) were adolescents aged 11-18 years (female = 22), 33 (80%) occurred within 15 minutes after vaccination, and 10 (24%) resulted in hospitalizations.

Conclusions:
Adolescents, especially females, contributed to the majority of syncope events reported to VAERS since 2005. To prevent secondary injuries from post-vaccination syncope, providers are reminded of current ACIP recommendations to observe patients for 15 minutes after vaccination.