Rotavirus vaccine associated with increased risk of intussusception

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1.  In the first 7 days after administration of the first dose, the pentavalent rotavirus vaccine, RotaTeq, was associated with an increased risk of intussusception by 1.5 excess cases per 100,000 doses given.

2. The relative risk of intussusceptions was roughly ten times lower for the pentavalent rotavirus vaccine as compared to the monovalent vaccine, Rotarix. 

Evidence Rating: 2 (Good)

Study Rundown: Rotavirus is a leading cause of diarrhea in children in developed countries.  The advent of a live-attenuated oral rotavirus vaccine has prevented over an estimated 50,000 hospitalizations per year.  However, an early iteration of the vaccine has also been associated with an increased risk of intussusception in young children.  Previously, there existed some equipoise regarding the risk of the monovalent vaccine, Rotashield (RV1), and the pentavalent vaccine, RotaTeq (RV5).  This study examined the rates of intussusception in children 5.0 to 36.9 weeks of age who received either RV1 or RV5 from January 2004 to September 2011.  Overall, the authors found that there were 1.5 excess cases of intussusception per 100,000 doses in children who received RV5, with no significant change in attributable risk after subsequent doses.  Because the great majority of children receive RV5 in the US, there was not enough data to statistically power the analysis of risk in children who receive RV1.  However, the authors estimate that RV1 is associated with an excess 7.3 cases per 100,000 doses.

Click to read the study in NEJM

Relevant reading: Uptake, Impact, and Effectiveness of Rotavirus Vaccination in the United States: Review of the First 3 Years of Postlicensure Data

In-Depth [retrospective study]: In this retrospective study, the rates of intussusception after administration of oral rotavirus vaccines in children aged 5.0 to 34.9 months were reviewed.  The study included 1,277,556 doses of RV5 and 103,098 doses of RV1.  Confirmed cases of intussusception were identified using the Brighton Collaboration criteria for diagnostic certainty.  Of 343 potential cases of intussusception, the authors identified 124 confirmed cases.  The first dose of RV5 was associated with an excess 1.1 cases of intussusceptions (95% CI, 0.3 to 2.7) in the 7-day risk window and 1.5 (95% CI, 0.2 to 3.2) in the 21-day risk window.  Subsequent doses of the vaccine were not associated with significantly increased risk.  There were not enough cases to apply self-controlled risk-interval (SCRI) analysis in the RV1 group but a cohort analysis attributed an excess 7.3 cases (95% CI, 0.8 to 22.5) after dose 2.  This study primarily used a SCRI analysis to compare the occurrence of intussusception in day 1 to 7 or day 1 to 21 risk interval to that in day 22 to 42 control interval.  Because there were not enough cases for statistical significance using SCRI, cohort analysis was done for RV1 data.  In the SCRI analysis, the dependence of rates of intussusception on age was normalized using well-curated background rates while a quadratic model of age-dependent risk was used for adjustment in the cohort analysis.

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