Rotavirus vaccines, such as Rotarix which is used in the UK, may be associated with a very small increased risk of a rare condition called intussusception, particularly if the vaccine is given later than recommended. In this condition, part of the bowel folds in on itself (like a collapsible telescope), causing an obstruction. It occurs naturally in some children under one year old (about 120 cases in every 100,000 children), with a peak at around 5 months of age. Intussusception needs urgent medical attention because it can be life-threatening. The symptoms are severe stomach pain, vomiting, and sometimes passing what looks like redcurrant jelly (blood in the baby’s nappy). Most children with intussusception are treated without complications and make a full recovery.
Research from some countries suggests that 2 extra cases of intussusception may occur for every 100,000 first doses of Rotarix that are given (within 7 days of vaccination). When compared to the number of cases that happen anyway (120 per 100,000 children), this is a very low additional risk (an increase to 122 per 100,000), and should be compared to the benefits of the vaccine in preventing severe rotavirus infection.
The first dose of Rotarix is always given before 15 weeks of age, as the side effect of intussusception seems unlikely to occur if the vaccine doses start at this age. This also reduces the chance of the vaccine being wrongly blamed for cases of intussusception that peak naturally at around 5 months of age. For this reason, there are strict rules about the age at which rotavirus vaccine should be given to babies, to avoid the risk of intussusception.
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