17 Rotavirus

17.7 Expected responses and adverse events following immunisation (AEFI)

The 2012 Cochrane review26 described above also reviewed the safety of RV1 and RV5 vaccines. No significant difference was found between children receiving RV1 or RV5 and placebo in the number of serious adverse events, and intussusception in particular (see below). No statistical differences were observed for fever, diarrhoea and vomiting between cases and placebo groups. There was no significant difference between cases and placebos in the number of adverse events leading to discontinuation of the schedule.

In 2010 porcine circovirus or porcine circovirus DNA was detected in both rotavirus vaccines. However, there is no evidence that this virus is a safety risk or causes illness in humans.44

17.7.1 Intussusception

Intussusception is a cause of an acute abdomen when one part of the intestine slides into another part of the intestine. In 1999 an oral human–rhesus rotavirus quadrivalent vaccine (RotaShield) was licensed in the US and on the infant schedule, but was withdrawn later that year after reports of an association with intussusception (a risk of approximately one case in 5000–10,000 vaccinees).

No increased risk of intussusception was detected in the large phase III pre-licensure clinical trials of RV1 (Rotarix) and RV5 (RotaTeq), despite this being a specifically monitored adverse event. However, post-marketing surveillance of both rotavirus vaccines indicates the possibility of an increased risk of intussusception shortly after the first dose of rotavirus vaccination. New evidence from Australia45 indicates that after the first dose, RV5 had a relative incidence (relative risk) of 9.9 (95% CI: 3.7–26.4, p < 0.001) and 6.3 (95% CI: 2.8–14.4, p < 0.001) for the periods of 1 to 7 days and 8 to 21 days after vaccination, respectively. For RV1, the relative incidence was 6.8 (95% CI: 2.4–19.0, p < 0.001) and 3.5 (95% CI: 1.3–8.9, p = 0.01) for the same time periods.

There was also some elevated risk of intussusception 1 to 7 days after the second dose of both vaccines. The relative incidence for RV5 was 2.8 (95% CI: 1.2–6.8, p = 0.02) and for RV1 it was 2.8 (95% CI: 1.1–7.3, p = 0.03). There was no evidence of increased risk of intussusception following a third dose of RV5.45

The increased risk of intussusception following rotavirus vaccination is estimated at approximately 6 additional cases of intussusception among every 100,000 infants vaccinated (approximately 1 in 15,500 vaccinees), or 14 additional cases per year in Australia.45

While there appears to be an increased relative risk of intussusception, the condition remains rare and this risk is outweighed by the benefits of rotavirus vaccination in preventing rotavirus infections, with an estimated 70 percent reduction in hospitalisations in young children after the vaccine’s introduction to the Australian schedule.46 It is uncertain whether rotavirus vaccine administration affects the overall incidence of intussusception: US data suggests no increased overall rate in infants despite a small cluster effect.47 Both the World Health Organization48 and the Australian Technical Advisory Group on Immunisation (ATAGI)46 continue to recommend the use of rotavirus vaccine for infants.