EVALUATION OF: Donato CM, Ch’ng LS, Boniface KF et al. Identification of strains of RotaTeq rotavirus vaccine in infants with gastroenteritis following routine vaccination. J. Infect. Dis. 206(3), 377–383 (2012).Two live, attenuated rotavirus vaccines, RotaTeq(®) (Merck) and Rotarix(®) (GlaxoSmithKline), have been used in Australia since July 2007 to prevent severe rotavirus gastroenteritis in children. Using active postvaccination monitoring, passive surveillance and state-of-the-art laboratory techniques, Donato et al. report that RotaTeq rotavirus vaccine and vaccine-derived strains were detected actively in stool samples from 13 out of 61 (21.3%) infants having diarrhea within 2 weeks of rotavirus vaccination, and among three out of 460 (0.7%) cases with acute gastroenteritis captured via the Australian Rotavirus Surveillance Program. Six (37.5%) of these 16 vaccine-derived viral specimens were associated with a G1P strain thought to be the result of genetic reassortment between two component RotaTeq strains. Although nearly half of these reassortant-associated cases had underlying medical conditions, such as severe combined immunodeficiency disorder, further study is needed to understand the relationship between shedding, viral reassortants and underlying medical conditions.