The team investigated the association between administration of an oral rotavirus vaccine and the development of intussusception in infants. The researchers reported their findings in the New England Journal of Medicine.
Intussusception is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment.
Hospitalized infants', one- to twelve-months old, were identified. Each infant with intussusception was matched according to age with four healthy control infants who had been born at the same hospital.
Data were analyzed for 429 infants with intussusception and 1,763 matched controls in a case-control analysis, as well as for 432 infants with intussusception in a case-series analysis.
|After the first dose of RRV-TV, risk of developing intussusception was 22-times normal.|
|N Engl J Med|
17.2% of the 429 infants with intussusception and 12.8% of the 1,763 controls had received RRV-TV.
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).
In the case-series analysis, the incidence-rate ratio was 29.4 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 this was smaller than after the first dose.
The authors estimated that one case of intussusception attributable to the vaccine would occur for every 4670 to 9474 infants vaccinated, assuming full implementation of a national RRV-TV vaccination program.
Dr Trudy Murphy, of the Centers for Disease Control and Prevention, Atlanta, concluded, "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."