Protective effects of natural rotavirus infection.

Rotavirus is a ubiquitous infection that is the leading cause of severe diarrhea worldwide. Severe infections are most commonly observed in the first 2 years of life. Rotavirus-induced diarrhea is associated with substantial morbidity and mortality rates and socioeconomic costs with adverse outcomes particularly prevalent in developing countries. The natural history of rotavirus infection can provide guidance for the development and optimization of an effective vaccine. Epidemiologic studies have demonstrated that children who acquire natural rotavirus infections develop immunity to subsequent infections, with the protective effect increasing with each natural infection. Natural infections also decrease the severity of any subsequent rotavirus infections. Notably, asymptomatic infections provide protection similar to that induced by symptomatic infections. Data also suggest that the antibody response to natural infection is heterotypic, and therefore may provide protection against multiple serotypes. These data suggest that the development of a vaccine that produces asymptomatic infection at an optimal time point may provide effective immunity. An effective vaccine should mimic protection provided by natural infection and provide protection against the most common rotavirus serotypes (ie, G1, G2, G3, G4, G9) and be able to decrease disease severity, reduce hospitalizations, and decrease disease-related costs.