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Is there an increased risk of intussusception in infants following vaccination against rotavirus?
The use of RotaTeq is associated with a small increase in the risk of intussusception following the first dose only (an excess of 1.5 cases per 100,000 vaccine recipients). The study was underpowered to detect whether Rotarix causes the same. This risk is roughly one-tenth that of the older Rotashield vaccine that was withdrawn from the market, and the vaccination of 4.3 million children is estimated to prevent more than 50,000 hospitalizations. (LOE = 2b)
Yih W, Lieu T, Kulldorff M, et al. Intussusception risk after rotavirus vaccination in US infants. N Engl J Med 2014;370(6):503-512. [PMID:10.1056/NEJMoa1303164]
International postlicensure studies have reported an increased risk of intussusception following vaccination with RotaTeq, a pentavalent rotavirus vaccine, and Rotarix, a monovalent version. This study sought to investigate the same among US infants aged between 5 weeks and 37 weeks. The researchers used claims data and medical records from 3 major health plans between January 2004 and September 2011 to identify vaccinated infants who were subsequently diagnosed with intussusception. All potential cases were classified and confirmed by external review. The authors studied this effect with 2 analytic approaches commonly employed in assessing vaccine safety: a self-controlled risk-interval design (the primary analysis) and a cohort design. Nearly 1.3 million RotaTeq and 100,000 Rotarix doses were included in the analyses, reflecting a half million and 50,000 first doses, respectively. Within the desired age range, 343 potential intussusception cases were initially identified, but only 267 were ultimately reviewed after accounting for missing charts. Of these, 124 cases were positively confirmed. For RotaTeq, the attributable risk (the number of excess cases of intussusception per 100,000 doses) was elevated both in both the 7-day and 21-day risk intervals following vaccination by 1.1 and 1.5 cases, respectively. No increased risk was seen after doses 2 or 3. For Rotarix, the primary analysis found no effect, but the cohort study approach revealed a significant attributable risk following dose 2 of 7.3 excess cases. The RotaTeq results are similar to those previously published using Vaccine Adverse Event Reporting System data. Lauren S. Hughes, MD, MPH Robert Wood Johnson Foundation Clinical Scholar® Department of Family Medicine University of Michigan