Rotavirus is the most common cause of severe gastroenteritis in infants and young children. The primary benefit of rotavirus vaccination is prevention of severe diarrheal disease and hospitalizations have been reduced dramatically since vaccine introduction. Rotavirus vaccination may impact antibiotic prescribing and resistance by two mechanisms. First, bacterial agents of gastroenteritis are often treated with antibiotics. Since aetiology is usually not known at the time of the medical encounter, antibiotics are frequently prescribed for viral gastroenteritis even though they are not recommended. Second, antibiotics, whether prescribed for gastroenteritis or infection at other sites, may disrupt the enteric microbiome. This may in turn lead to other secondary bacterial infections, mainly Clostridium difficile infection (CDI). C difficile is inherently resistant to most groups of antibiotics, such as aminoglycosides, penicillins, cephalosporins, and fluoroquinolones, hence treatment options are limited. In this study, we aim to 1) estimate the effect of rotavirus vaccination on antibiotic prescribing 2) estimate the effect of rotavirus vaccination on CDI. We will conduct a large retrospective cohort study constructed from MarketScan databases. Analysis will be performed using longitudinal, individual-level data. These findings can provide evidence for national and international bodies for vaccine decision-making and antimicrobial resistance control strategies.