Proffered Papers Australian Society for Microbiology Annual Scientific Meeting 2016

Rotavirus infections in the vaccine era – a community-based birth cohort study (#25)

Suifang Ye 1 2 3 , David M Whiley 1 3 , Stephen B Lambert 4 , Theo P Sloots 2 , Carl D Kirkwood 5 6 7 , Keith Grimwood 8
  1. University of Queensland Centre for Clinical Research, The University of Queensland, Brisbane , QLD, Australia
  2. Queensland Paediatric Infectious Diseases Laboratory, Children’s Health Queensland , Brisbane , Queensland, Australia
  3. Microbiology Division, Pathology Queensland Central Laboratory, Herston, Queensland, Herston , Queensland, Australia
  4. UQ Child Health Research Centre , Brisbane , Queensland, Australia
  5. Murdoch Childrens Research Institute , Melbourne , Victoria, Australia, Australia
  6. La Trobe University, Melbourne, Victoria, Australia, Victoria , Australia
  7. University of Melbourne , Melbourne , Victoria , Australia
  8. Menzies Health Institute Queensland , Griffith University and Gold Coast Health, Gold Coast , Queensland , Australia

The introduction of rotavirus (RV) vaccines into the childhood immunisation programs has been highly effective in reducing the burden of RV-related disease. Specific surveillance is now required to understand the post-vaccine implementation epidemiology of RV. In this study we investigated RV infections and circulating RV strains in young Australian children following the inclusion of RV vaccines into the national immunisation program in 2007.

The Observational Research in Childhood Infectious Diseases (ORChID) birth cohort study was conducted in Brisbane, Queensland, Australia where newborn infants were progressively enrolled between September 2010 and October 2012 and followed until their second birthday. Parents collected weekly nappy swabs from their children and mailed these to the Queensland Paediatric Infectious Diseases (QPID) research laboratory. The samples were tested for rotavirus by RT-PCR, and RV-positive samples were subjected to P and G-genotyping.

A total of 11,198 nappy swabs were received from 158 infants. Overall, any rotavirus was detected in 139 (88.0%) infants and 1,069 (9.5%) nappy swabs. We were unable to genotype 77 RV-positive specimens due to low viral load. Genotyping of the remaining specimens showed that the RotaTeq vaccine strain (the publicly funded vaccine in Queensland) accounted for 947 (88.6%) of all RV-positive samples. Four different wild-type RV genotypes were observed in a further 45 samples from 20 children: G12P[8] (n=29), G2P[4] (11), G1P[8] (3), and G4P[8] (2). Shedding of virus was observed on average for 3.5 weeks for vaccine virus (ranging from 1 to 19 weeks) and for 1.8 weeks for wild-type virus (ranging from 1 to 6 weeks). The latter included 12 wild-type infections (G1P[8], G2P[4] and G12P[8]) detected at 17 to 79 weeks following receipt of their final dose of vaccine.

We found frequent detection of rotavirus in the stool samples of infants from our cohort; these detections were often, but not always, RV vaccine viruses. In the vaccine era, genotyping is required to understand RV epidemiology in recently vaccinated cohorts.