The risk of rotavirus infection and diarrhea decreased with increasing age, corresponding with an increase in IgG and IgA antibody titers increased with increasing age [14]. However, no threshold level of protection was observed for either IgG or IgA [14]. The globally common G1P[8], G2P[4], and G9P[8] rotavirus strains were also the most frequently detected strains in numerous studies in India in both inpatients and outpatients<5 years of age [4], [5], [7], [8], [9] and [10].

G12 and G9P[4] were also detected in many studies [4], [5], [7], [8], [9] and [10]. In the birth cohort study in Vellore, G10P [11] was frequently detected in infections in neonates [13]. Another study compared circulating Angiogenesis inhibitor rotavirus strains in children <5 years of age and in animals collected in the same area in south India during similar time periods

[15]. The common G types in children were similar to those detected in other hospital based surveillance studies (G1, G2, and G9). Of the animals tested for rotavirus, 35 (5.5%) of 627 were positive for rotavirus with G6, G2, and G10 as the most common G types and P[6] and P[4] as the most common P-types. G2 infections, which are predominately detected in humans, are rare in animals suggesting anthroponotic transmission occurs in southern India. One unusual P-type, P[15], find more was detected in combination with G10. Several studies noted a high false positivity rate using ELISA ranging from 13% of results as false positives in children to over 50% in adolescents and adults [11] and [16]. These false positive detections complicated aminophylline interpretation of the ELISA results and often required additional testing to determine true positives. For example, samples that are untypeable using standard PCR-based methods may be due to false positive results on ELISA. To help characterize untypeable strains, Babji and colleagues propose a typing strategy based on available primers but using alternate extraction methods and showed that this strategy, combined with sequencing, is able to resolve the majority of untypeable strains [16]. In sequencing studies of circulating strains, naturally circulating

G1P[8] strains differ from subgenotypic linages of the G1P[8] strains in both of the currently available international vaccines, Rotarix and RotaTeq, but the relationship of these sublineages to vaccine effectiveness is unknown [17]. Circulation of intergenogroup reassortants was detected among adolescents and adults [12]. Rotavirus diarrhea results in a significant economic burden to India [3]. Rotavirus hospitalizations among children <5 years of age are estimated to cost INR 4.9 billion (USD ∼81.6 million) each year in India and rotavirus outpatient visits an additional INR 5.38 billion (USD ∼89.5 million) per year. A national rotavirus vaccination program if implemented by the Government of India would cost Rs 60 (USD 1) per dose with a total cost of INR 4.47 billion per year which is less than the annual cost of rotavirus hospitalizations.