The first-generation rotavirus vaccine RotaShield was withdrawn in 1999 because of a 1 in 10 000 risk of intussusception. The second-generation vaccines—RotaTeq, a pentavalent bovine-human reassortant vaccine, and Rotarix (RV1), a monovalent human vaccine—underwent extensive clinical trials with no apparent increased risk of intussusception. In 2006–2007, Brazil and Mexico introduced routine infant immunisation with RV1. Now, a study in both countries (Manish M Patel, and colleagues. New Engl J Med 2011;364:2283–92; …