Intussusception among recipients of rotavirus vaccine: reports to the vaccine adverse event reporting system.

BACKGROUND: Rotavirus vaccine was licensed on August 31, 1998, and subsequently recommended for routine use among infants. To assess rare adverse events, postlicensure surveillance was conducted. OBJECTIVE: To describe the cases of intussusception among rotavirus vaccine recipients reported to the Vaccine Adverse Event Reporting System from October 1998 through December 1999. SETTING AND PARTICIPANTS: Infants vaccinated with rotavirus vaccine in the United States. OUTCOME MEASURES: Intussusception confirmed by radiology, surgery, or autopsy report with medical record documentation or confirmed by a primary health care provider. RESULTS: There were 98 confirmed cases of intussusception after vaccination with rotavirus vaccine reported to the Vaccine Adverse Event Reporting System; 60 of these developed intussusception within 1 week after vaccination. Based on calculations using vaccine distribution data and intussusception incidence rates from 2 separate databases, an estimated 7 to 16 cases would have been expected to occur in the week after vaccination by chance alone. CONCLUSION: Using a passive surveillance system for vaccine adverse events, we observed at least a fourfold increase over the expected number of intussusception cases occurring within 1 week of receipt of rotavirus vaccine. Other studies were initiated to further define the relationship between rotavirus vaccine and intussusception. In light of these and other data, the rotavirus vaccine manufacturer voluntarily removed its product from the market, and the recommendation for routine use of rotavirus vaccine among US infants has been withdrawn.

A comparison of two time intervals for the ausculated acceleration test.

OBJECTIVE: Interest in an inexpensive, easy-to-administer antenatal screening test that did not rely on the use of electronic fetal monitoring led to development of the fetoscope administered auscultated acceleration test (AAT) in the late 1980s. More recent efforts have been directed toward providing those who may use the AAT with important information about the most effective and clinically appropriate AAT procedures. The purpose of this study was to determine the screening test validity performance of two AAT time intervals--6 minutes and 10 minutes. METHODS: Two auscultated acceleration tests (AAT6 and AAT10) were simultaneously performed using different time intervals on 205 women with high-risk pregnancies undergoing simultaneous nonstress tests (NSTS) who were referred to a tertiary care unit for antepartum testing. Standard measurements of screening test validity were calculated for each test in the prediction of selected perinatal outcomes. NST findings were included for comparative purposes. RESULTS: The AAT6 yielded an overall higher specificity as compared with the AAT10 at the expense of a slightly lower sensitivity for most perinatal outcomes; these differences were not significant at the .05 level. Relative risk ratios were similar for the AAT6 and AAT10 for both fetal distress and neonatal morbidity, with both AAT being a more effective predictor of neonatal morbidity than for fetal distress. Both tests yielded better sensitivity when compared with NST. CONCLUSIONS: Even though there was a nonsignificant trend toward higher sensitivities and lower specificities for the 10-minute AAT, this study showed that the differences in prediction of perinatal outcomes between the 6-minute and 10-minute AAT were minimal. In view of the added labor required for the 10-minute AAT in the absence of enhanced screening test validity, the 6-minute AAT is clinically preferred. This study has prompted new research questions for the continued development of the AAT as a low-technology fetal assessment technique with potential usefulness by midwives and their colleagues in a variety of settings worldwide.

Intussusception among infants given an oral rotavirus vaccine.

BACKGROUND: Intussusception is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment. Our investigation began on May 27, 1999, after nine cases of infants who had intussusception after receiving the tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV) were reported to the Vaccine Adverse Event Reporting System. METHODS: In 19 states, we assessed the potential association between RRV-TV and intussusception among infants at least 1 but less than 12 months old. Infants hospitalized between November 1, 1998, and June 30, 1999, were identified by systematic reviews of medical and radiologic records. Each infant with intussusception was matched according to age with four healthy control infants who had been born at the same hospital as the infant with intussusception. Information on vaccinations was verified by the provider. RESULTS: Data were analyzed for 429 infants with intussusception and 1763 matched controls in a case-control analysis as well as for 432 infants with intussusception in a case-series analysis. Seventy-four of the 429 infants with intussusception (17.2 percent) and 226 of the 1763 controls (12.8 percent) had received RRV-TV (P=0.02). An increased risk of intussusception 3 to 14 days after the first dose of RRV-TV was found in the case-control analysis (adjusted odds ratio, 21.7; 95 percent confidence interval, 9.6 to 48.9). In the case-series analysis, the incidence-rate ratio was 29.4 (95 percent confidence interval, 16.1 to 53.6) for days 3 through 14 after a first dose. There was also an increase in the risk of intussusception after the second dose of the vaccine, but it was smaller than the increase in risk after the first dose. Assuming full implementation of a national program of vaccination with RRV-TV, we estimated that 1 case of intussusception attributable to the vaccine would occur for every 4670 to 9474 infants vaccinated. CONCLUSIONS: The strong association between vaccination with RRV-TV and intussusception among otherwise healthy infants supports the existence of a causal relation. Rotavirus vaccines with an improved safety profile are urgently needed.