The age PARP inhibitor at which the children was administered the first dose might play an important role in determining seroconversion rates. In this study and

the study with Rotarix™ in Vietnam the average age of first dose administration was 8 weeks. In comparison, the average age for the first dose in the US is 9–11 weeks and 11–17 weeks in Singapore [23] and [24]. In Finland and Italy, vaccine has been used at even older age (3 months) [17]. It is generally believed that vaccination at older age induces better immune responses possibly due to a more mature immune system of the child and declining maternal antibody titers in breast milk or from placental transmission. This notion is also supported by a study of Rotarix™ in the Philippines in which children were 5.5 weeks of age at the first dose and the seroconversion rate was lower compared to that in Vietnamese children. As vaccines, Rotavin-M1 is very similar to Rotarix™ in that both are derived from common G1P [8] strains attenuated

by serial passage and prepared in Vero cells. Like Rotarix™, the majority of children mTOR kinase assay shed after the 1st dose of Rotavin-M1, whereas this proportion declined considerably after 2nd dose, similar to other studies [24]. Shedding of Rotarix™ in different studies worldwide is 35–80%, corresponding to the shedding rate of this vaccine found in our study [27]. One interesting difference between the behavior of the two vaccines is the increased shedding observed for Rotarix™ (65%) compared to Rotavin-M1 (44–48%) after the 1st dose although this was not accompanied by an increased immune response. Another difference between the two vaccines is that Rotavin-M1 vaccine, at the dosage of 106.0 FFU or 106.3 FFU caused delayed in virus shedding compared to Rotarix™ at doses of 106 CCID50 (corresponding to 105.5 FFU/dose). These differences between the two vaccines suggest that further research on vaccine formulation, improving the yield of virus so that higher titer candidates could be available which helps advance the development

of this locally manufactured vaccine through efficacy trials. In this study, the Rotavin-M1 was administered separately from most the oral polio virus vaccine (OPV) (10–20 days from the EPI schedule), thus the study was not designed to investigate the effect of other vaccines, in particular OPV on Rotavin-M1. While the coadministration of Rotarix or RotaTeq with OPV seemed to reduce seroconversion rates, antibody titers and vaccine take compared to rotavirus vaccines without OPV, the reductions were not statistically significant [28] and [29]. Thus further study should be designed to investigate whether there is any interference to Rotavin immunogenicity due to concomitant usage of OPV and Rotavin-M1. This study has several limitations which will need to be addressed as development of this vaccine progresses.