Health & Medical Vaccinations

Rotavirus Vaccination: Short vs Long-term Herd Protection

Rotavirus Vaccination: Short vs Long-term Herd Protection

Background


Two rotavirus vaccines have been licensed in the USA. RotaTeq (RV5; Merck, NJ, USA) was licensed in 2006 and is a live pentavalent human–bovine reassortant vaccine that has attenuated ability to replicate in humans. Rotarix (RV1; GlaxoSmithKline, Brentford, UK) was licensed in 2008 and is a monovalent live laboratory-attenuated vaccine. Prior to vaccine implementation, rotavirus was the most common identifiable cause of gastroenteritis in children <5 years of age, with the highest rates of hospitalization occurring in children 6–24 months of age. Despite the burden of disease, implementation of rotavirus vaccination was projected to cost society US$216 million. Notably, this estimate only accounted for rotavirus disease in children <5 years of age and did not consider indirect protection of unvaccinated populations.

Serial observations of a cohort of newborns in Mexico until the age of 2 years provided important insights into wild-type rotavirus. By 2 years of age, 96% of children had at least one rotavirus infection, with more than two-thirds having had ≥two infections. Prior infection was associated with protection against subsequent moderate-to-severe disease (adjusted relative risk: 0.13; 95% CI: 0.04–0.50), and any subsequent infection was usually due to a different rotavirus serotype. This study suggested that prior infection generated primarily serotype-specific immunity but also substantial cross-protection against moderate-to-severe disease due to other serotypes. These data provided hope that a live rotavirus vaccine might stimulate a similar immune response to that observed with wild-type rotavirus infection, providing protection against moderate-to-severe rotavirus disease with any serotype. Prelicensure data supported this hypothesis by demonstrating that RV1 and RV5 resulted in an 85–95% decline in moderate-to-severe disease (emergency department visits and hospitalizations), while efficacy against all rotavirus-related disease was lower at about 75%.

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