Indeed, during the second year of follow-up, 96 cases of severe RVGE were detected. During the second year of follow-up the point estimate of vaccine

efficacy was 19.2%. We surmise that if a similarly intense and culturally compatible surveillance Afatinib purchase system had also been utilized through the first year of follow-up, the number of cases of severe RVGE detected would have been greatly increased due to the higher burden of severe rotavirus GE in the first year of life. Thus, the estimate of vaccine efficacy may have been higher. The composite of experiences in poorer developing countries in Africa and Asia now provides convincing evidence that the level of efficacy of oral RV vaccines measured in individual subject-randomized,

double-blind, controlled field trials (approximately 50–65% efficacy) is lower [7], [8] and [24] than the efficacy of vaccine documented in controlled field trials in industrialized Buparlisib clinical trial and transitional countries [3] and [4]. The reduced immunogenicity and efficacy of both live and non-living oral vaccines in populations in developing countries has been previously described with multiple vaccines, such as oral polio vaccine, cholera vaccine and Shigella vaccines [25], [26], [27], [28], [29], [30], [31], [32], [33] and [34] and is the subject of much discussion and research to understand the basis of this phenomenon. Possibilities include potential vaccine factors, such as restricted immunogenicity or host factors such as gut enteropathy, and co-morbidities as described elsewhere [35], [36] and [37] This has led some to become discouraged about what live oral RV vaccines can accomplish in the world’s least developed countries (where RV vaccines are most needed) and to propose

starting afresh on new vaccine strategies such as parenterally administered inactivated unless vaccines [38] and [39]. On the other hand, there are also clear reasons for optimism. The immunogenicity in Mali was comparable to that in Ghana and Kenya, where sufficient numbers of cases were captured to yield site-specific efficacies of 65.0% and 83.4%, respectively, through the first year of life [4] and [40]. Moreover, it is likely that the actual impact of widespread immunization of infants in Mali with live oral RV vaccine would result in an impact far greater than anticipated based just on the estimate of vaccine efficacy because of indirect protection and a herd immunity effect. Experiences in the U.S.A. [41], [42], [43] and [44], Australia [45], [46] and [47], and Latin America [48] show an unequivocal herd immunity effect wherein the observed fall in rotavirus disease far exceeds the expectation based just on estimates of direct vaccine efficacy and immunization coverage.