Vesikari T et al. (2006) Safety and efficacy of a pentavalent human–bovine (WC3) reassortant rotavirus vaccine. N Engl J Med 354: 23–33

Ruiz-Palacios GM et al. Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis. N Engl J Med 354: 11–22

Results of two multinational, randomized, double-blind, placebo-controlled trials that together enrolled 131,263 children have confirmed the safety and efficacy of two new oral rotavirus vaccines.

RotaTeq® (Merck) is a human–bovine reassortant vaccine against G1, G2, G3, G4 and P[8] serotypes of human rotavirus. Crucially, the results of this 4-year study, which enrolled 68,038 infants aged 6–12 weeks, mainly from industrialized countries, showed no evidence of an increased risk of intussusception among vaccinated children, compared with those given placebo (links with this rare, but severe, complication necessitated withdrawal of a previous rotavirus vaccine). The vaccine was highly effective at preventing severe rotavirus gastroenteritis and provided substantial protection against rotavirus gastroenteritis of any severity, resulting in a marked reduction in associated hospitalizations and use of health-care resources.

Similar safety and efficacy results were shown for Rotarix® (GlaxoSmithKline), an attenuated vaccine specific for G1P[8] human rotavirus. This study enrolled 63,225 infants aged 6–13 weeks, mainly from Latin American countries, in which serotype G1P[8] predominates. Importantly, the authors found that Rotarix® could cross-protect against other rotavirus serotypes, albeit with reduced efficacy. Overall, rotavirus-associated hospitalizations were reduced by 42% in the Rotarix® study and by 63% in the RotaTeq® study. Questions remain as to whether these vaccines are equally safe in older children, but their potential is huge: worldwide, rotavirus infection kills ∼500,000 children annually (mostly in developing countries) and accounts for a third of hospitalizations for diarrhea.