Assessing the effectiveness and public health impact of rotavirus vaccines after introduction in immunization programs.

Two new vaccines against severe rotavirus gastroenteritis that have high efficacy in middle- and high-income countries have recently been licensed in many countries worldwide. Clinical trials in low-income countries in Africa and Asia are ongoing. Experience gained through studies of natural rotavirus infection and the clinical trials for the current and previous rotavirus vaccines indicate that, as countries begin to introduce these newly approved vaccines into routine childhood immunization programs, monitoring their performance in real world settings should be a high priority. Key epidemiological considerations in the postlicensure period include (1) how the vaccine will perform against severe rotavirus disease under routine public health use; (2) how routine vaccination will impact the epidemiology of disease with regard to the burden of severe disease and death, age distribution of cases, seasonality, and serotype distribution; (3) whether vaccination will have a sufficient impact on transmission to reduce disease burden in unvaccinated age groups; and (4) whether vaccine will confer protection through the first 3 years of life, when most severe disease and mortality associated with rotavirus occur. Monitoring of impact with focus on these public health considerations will allow parents, health care providers, and decision makers to appreciate the health benefits of vaccination in reducing the burden of severe rotavirus disease. It will also allow assessment of the effectiveness of rotavirus vaccines in programmatic use and the need for modifying vaccination schedules or vaccine formulations to enhance the performance of immunization. In this article, we review data for the protective efficacy of the 2 new rotavirus vaccines, with emphasis on issues particularly important for consideration as these vaccines are introduced in routine infant immunization programs.