KEYWORDS:
vaccines, gastroenteritis, intussusception, adverse effects, postmarketing surveillance

BACKGROUND:
The first licensed rotavirus vaccine, rhesus-human rotavirus reassortant-tetravalent vaccine (RRV-TV), was recommended for use in the United States in 1998. Due to increased risk of intussusception, however, the recommendation for its routine use was withdrawn about nine months later after about 1.5 million doses had been administered.

OBJECTIVE(S):
To more fully characterize the postmarketing safety profile of RRV-TV by further analyses of the Vaccine Adverse Event Reporting System (VAERS).

METHOD(S):
Excluding confirmed and suspected intussusception reports, proportional morbidity were compared among remaining VAERS reports of infants who received 1) RRV-TV alone, 2) RRV-TV in combination with other vaccines, and 3) other vaccine combinations without RRV-TV. All 446 nonfatal intussusception and non-intussusception reports after RRV-TV were reviewed and recoded from the clinical description on the VAERS report and manual cluster analysis performed to better describe the spectrum of illnesses.

RESULT(S):
Even after excluding intussusception cases, the remaining RRV-TV reports were more likely than non-RRV-TV recipients to experience fever and various gastrointestinal symptoms, notably bloody stool (as well as vomiting, diarrhea, abdominal pain, gastroenteritis, abnormal stool and dehydration) (p<0.005). Manual cluster analysis revealed six clusters including: diagnosed intussusception (25%), suspect intussusception (8%), illness consistent with intussusception or gastroenteritis (7%), gastroenteritis (22%), other gastrointestinal outcomes (2%), and non-gastrointestinal outcomes (35%).

CONCLUSIONS(S):
Using a passive surveillance system for vaccine adverse events, we demonstrated an increase in fever and gastrointestinal outcomes other than intussusception after RRV-TV when compared to other vaccines. Intussusception and gastroenteritis are the most common reported outcomes; however, a substantial number of reports indicate signs and symptoms consistent with either illness, suggestive of a spectrum of gastrointestinal illness. This more complete safety profile of RRV-TV may aid better understanding of the pathophysiology of intussusception.

LEARNING OBJECTIVES:
To fully characterize the postmarketing safety profile of gastrointestinal outcomes following RRV-TV reports to VAERS.