BACKGROUND: Introduction of rotavirus vaccines into national immunization 
programs (NIPs) could result in strain selection due to vaccine-induced 
selective pressure. This study describes the distribution and diversity of 
rotavirus genotypes before and after rotavirus vaccine introduction into the 
Australian NIP. State-based vaccine selection facilitated a unique comparison of 
diversity in RotaTeq and Rotarix vaccine states.
METHODS: From 1995 to 2015, the Australian Rotavirus Surveillance Program 
conducted genotypic analysis on 13051 rotavirus-positive samples from children 
<5 years of age, hospitalized with acute gastroenteritis. Rotavirus G and P 
genotypes were determined using serological and heminested multiplex 
reverse-transcription polymerase chain reaction assays.
RESULTS: G1P[8] was the dominant genotype nationally in the prevaccine era 
(1995-2006). Following vaccine introduction (2007-2015), greater genotype 
diversity was observed with fluctuating genotype dominance. Genotype 
distribution varied based on the vaccine implemented, with G12P[8] dominant in 
states using RotaTeq, and equine-like G3P[8] and G2P[4] dominant in states and 
territories using Rotarix.
CONCLUSIONS: The increased diversity and differences in genotype dominance 
observed in states using RotaTeq (G12P[8]), and in states and territories using 
Rotarix (equine-like G3P[8] and G2P[4]), suggest that these vaccines exert 
different immunological pressures that influence the diversity of rotavirus 
strains circulating in Australia.