The Withdrawl of the Rotashield Rotavirus Vaccination Due to an Association with Intussusception: Fact or Fiction?

Rotavirus exists throughout the world and is estimated to have infected every individual by their fifth birthday. For this reason, there has been a significant drive for the development of a vaccination for the virus. After much failure, Rotashield, a tetravalent rhesus-based live attenuated vaccine was developed and approved in 1998. Following over 1.5 million administrations, it was suspended from the market in July 1999 and finally removed entirely in November of the same year due to fears of increased rates of intussusception following vaccination. Previous studies have shown a relationship between adenovirus infection and increased rates of intussusception. However similar relationships with wild-type rotavirus infection have not been demonstrated. Though studies have shown as much as a 25 times greater risk of developing intussusception within one week of vaccination, they fail to provide convincing conclusions. Past studies have either failed to include proper control groups which account for recency of wild-type rotavirus infection, consider cumulative rates of intussusception, or include sample sizes large enough to detect differences in intussusception rates.