Background: From 2016, the Government of India introduced the oral rotavirus vaccine into the national immunization schedule. Currently, two indigenously developed vaccines (ROTAVAC, Bharat Biotech; ROTASIIL, Serum Institute of India) are included in the Indian immunization program. We report the rotavirus disease burden and the diversity of rotavirus genotypes from 2005 to 2016 in a multi-centric surveillance study before the introduction of vaccines.
Methods: A total of 29,561 stool samples collected from 2005 to 2016 (7 sites during 2005-2009, 3 sites from 2009 to 2012, and 28 sites during 2012-2016) were included in the analysis. Stools were tested for rotavirus antigen using enzyme immunoassay (EIA). Genotyping was performed on 65.8% of the EIA positive samples using reverse transcription- polymerase chain reaction (RT-PCR) to identify the G (VP7) and P (VP4) types. Multinomial logistic regression was used to quantify the odds of detecting genotypes across the surveillance period and in particular age groups.
Results: Of the 29,561 samples tested, 10,959 (37.1%) were positive for rotavirus. There was a peak in rotavirus positivity during December to February across all sites. Of the 7215 genotyped samples, G1P (38.7%) was the most common, followed by G2P (12.3%), G9P (5.8%), G12P (4.2%), G9P (4%), and G12P (2.4%). Globally, G9P and G12P are less common genotypes, although these genotypes have been reported from India and few other countries. There was a variation in the geographic and temporal distribution of genotypes, and the emergence or re-emergence of new genotypes such as G3P was seen. Over the surveillance period, there was a decline in the proportion of G2P, and an increase in the proportion of G9P. A higher proportion of mixed and partially typed/untyped samples was also seen more in the age group 0-11 months.
Conclusions: This 11 years surveillance highlights the high burden of severe rotavirus gastroenteritis in Indian children < 5 years of age before inclusion of rotavirus vaccines in the national programme. Regional variations in rotavirus epidemiology were seen, including the emergence of G3P in the latter part of the surveillance. Having pre-introduction data is important to track changing epidemiology of rotaviruses, particularly following vaccine introduction.
Keywords: Diarrhoea; Enzyme immunoassay; Gastroenteritis; Genotypes; India; Polymerase chain reaction; Rotavirus.