In the July 16, 1999 edition of Morbidity and Mortality Weekly (MMWR 48(27);577-581) (http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/mm4827a1.htm), the Centers for Disease Control called for a moratorium on the use of Rotavirus Vaccine (RotaShield). Since its availability in September 1998, a total of 15 cases of intussusception have been reported in infants who have received the vaccine. All cases were reported spontaneously to the Vaccine Adverse Event Reporting System (VAERS).

Intussusception, the tunneling or invagination of a segment of bowel into another, occurs infrequently in infants, with an estimated incidence of 45-50 cases per 100,000 infant-years. The observed incidence associated with the administration of RotaShield is 300 per 100,000 infant-years. Wyeth Ayerst, the manufacturer of RotaShield), distributed an estimated 1.8 million doses of vaccine through June 1, 1999 according to MMWR, with an estimated 1.5 million doses administered. Based on this volume of use, it was estimated that up to 14-16 cases of intussusception would be expected by pure chance during any given week. According to the CDC, "Of the 15 infants with intussusception reported to VAERS, 13 (87%) developed intussusception following the first dose of the three-dose RRV-TV series, and 12 (80%) of 15 developed symptoms within 1 week of receiving any dose of RRV-TV. Thirteen of the 15 patients received concurrently other vaccines with RRV-TV. Intussusception was confirmed radiographically in all 15 patients." These data, coupled with a more detailed examination of patient experience in managed care plans in California and Minnesota, strongly suggest a link between administration of RotaShield and the development of intussusception, albeit not statistically significant. According to MMWR, "In prelicensure studies, five cases of intussusception occurred among 10,054 vaccine recipients and one of 4633 controls, a difference that was not statistically significant . Three of the five cases among vaccinated children occurred within 6-7 days of receiving rotavirus vaccine. On the basis of these data, intussusception was included as a potential adverse reaction on the package insert, and the ACIP [Advisory Committee on Immunization Practices] recommended postlicensure surveillance for this adverse event following vaccination."

According to the MMWR, "CDC recommends postponing administration of RRV-TV to children scheduled to receive the vaccine before November 1999, including those who already have begun the RRV-TV series. Parents or caregivers of children who have recently received rotavirus vaccine should promptly contact their health-care provider if the infant develops symptoms consistent with intussusception (e.g., persistent vomiting, bloody stools, black stools, abdominal distention, and/or severe colic pain). Health-care providers should consider intussusception in infants who have recently received RRV-TV and present with a consistent clinical syndrome; early diagnosis may increase the probability that the intussusception can be treated successfully without surgery. Vaccine providers, parents, and caregivers should report to VAERS intussusception and other adverse events following vaccination. Information on reporting to VAERS and case report forms can be requested 24 hours a day by telephone, (800) 822-7967, or the World-Wide web, http://www.cdc.gov/nip/vaers.htm."