Background: A pentavalent, bovine-derived rotavirus vaccine (RotaTeq, Merck) was licensed in 2006 for use in infants. A previously licensed rotavirus vaccine was withdrawn due to elevated risk of intussusception. We prospectively evaluated the risk of intussusception and other pre-specified adverse events among RotaTeq recipients in the Vaccine Safety Datalink.
Methods: The exposed population included children from age 4 to 48 weeks who received RotaTeq between May 2006 and May 2008. Adverse events over the subsequent 30 days were ascertained from inpatient, outpatient, and emergency department files; cases of intussusception were validated by medical record review. An adaptation of sequential probability ratio testing was employed to compare the cumulative number of observed and expected adverse events on a weekly basis, and a “signal” was generated if the log-likelihood ratio reached a predetermined threshold. This allowed near real-time monitoring to detect selected adverse events. The expected number of cases of intussusception was determined from historical rates in the VSD population.
Results: There were 207,621 doses of RotaTeq administered to the study population; 42% were first doses. Five children had computerized diagnosis codes for intussusception, and 6.75 cases were expected based on historical rates (relative risk = 0.74). No elevation in risk was identified for intussusception or any other adverse event. Two of five children with suspected intussusception based on diagnosis codes met the case criteria after medical record review.
Conclusions: This study illustrates the feasibility of rapid vaccine safety assessment and provides additional evidence that RotaTeq is not associated with an increased risk of intussusception.
From the *Marshfield Clinic Research Foundation, Marshfield, WI; †Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA; ‡Kaiser Permanente of Northern California, Oakland, CA; §Division of General Pediatrics, Children's Hospital, Boston, MA; and ¶Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA.
Accepted for publication May 22, 2009.
This study was funded through a subcontract with America's Health Insurance Plans (AHIP) under contract 200-2002-00732 from the Centers for Disease Control and Prevention (CDC).
Members of the Vaccine Safety Datalink Investigation Group include: Roger Baxter, Jason Glanz, Simon Hambidge, Lisa Jackson, Nicola Klein, Allison Naleway, James Nordin, and Richard Platt.
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the funding agency.
Address for correspondence: Edward A. Belongia, MD, Marshfield Clinic Research Foundation, Epidemiology Research Center (ML2), 1000 North Oak Ave, Marshfield, WI 54449. E-mail: firstname.lastname@example.org.
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