Where They Are Needed Most?

Rotavirus vaccines hold promise to decrease the burden of severe diarrhea in the poorest countries, where 85 % of deaths due to rotavirus occur. However, the potency of live oral vaccines is lower in these challenging settings than in middle- and upper-income countries. Many hypotheses have been suggested to explain these differences that could provide clues to improve the ultimate success of these novel vaccines. Although intro-duction today of even moderately effective vaccines will decrease the morbidity and mortality associated with rotavirus in low-income settings, research is urgently needed to understand why these differences in efficacy occur and what could be done to improve vaccine performance to maximize the life-saving benefits of vaccination. Rotavirus vaccines could have their greatest health ben-efit in the poorest developing countries in Africa and Asia where 185 % of the estimated 527,000 deaths from rotavirus diarrhea currently occur [1, 2]. Two vaccines, Rotarix (GlaxoSmithKline) and RotaTeq (Merck), have demonstrated good efficacy (85%–98%) against severe rotavirus diarrhea in clinical trials conducted in the Americas and Europe [3, 4], and these vaccines have already been introduced in the routine immunization schedule of several countries in these regions. Although these vaccines have been licensed in 1100 countries Potential conflicts of interest: none reported