Reducing the burden of gastroenteritis for Aboriginal children

  • Bianca Middleton

Student thesis: Doctor of Philosophy (PhD) - CDU

Abstract

Rotavirus is the leading global cause of diarrhoea associated morbidity and mortality among young
children. Before vaccination, rotavirus was estimated to cause more than 10,000 hospitalisations and
22,000 emergency department presentations for Australian children < 5 years old, every year. The
burden of disease was even greater for Aboriginal and Torres Strait Islander children, particularly those
living in rural and remote Australia, where rotavirus outbreaks occurred frequently on the background
of high levels of endemic infection.

This thesis reviews the health impact of the first fifteen years of the oral rotavirus vaccine program in
Australia and reports a significant decrease in the burden of rotavirus disease for most Australian
children. However, for Aboriginal and Torres Strait Islander children the relative decrease in
hospitalisations has been smaller and the residual burden of severe rotavirus gastroenteritis remains
much higher. While contributing factors include less complete vaccine coverage and reduced vaccine
timeliness, observational studies indicate that decreased and waning rotavirus vaccine effectiveness is
also likely among Aboriginal and Torres Strait Islander children living in remote Australia.

The ORVAC study – Optimising Rotavirus Vaccine in Aboriginal Children, is an adaptive clinical trial
which seeks to improve and extend the effectiveness of oral rotavirus vaccines by administering an
additional or ‘booster’ dose of rotavirus vaccine to Aboriginal and Torres Strait Islander children 6 to
< 12 months old. This thesis reports the results of ORVAC Stage 1, which found evidence of improved
vaccine seroresponse among children who received an additional dose of rotavirus vaccine (85%)
compared to placebo (72%). However, evidence of a reduction in diarrhoeal disease is needed to change
rotavirus vaccine policy and practice.

This body of work provides important insights into reduced rotavirus vaccine effectiveness and high
residual burden of rotavirus gastroenteritis for Australian Aboriginal and Torres Strait Islander children
and presents evidence that administering an additional dose of oral rotavirus vaccine leads to improved
vaccine immune response in this population. These findings have provided the basis for ORVAC Stage
2, which will enrol up to 1000 Aboriginal and Torres Strait Islander children to determine if
administration of an additional or ‘booster’ dose of oral rotavirus vaccine leads to decreased medical
presentations with gastroenteritis in the first three years of life. If so, this would be a feasible and readily
implementable strategy to further reduce the burden of gastroenteritis among Aboriginal and Torres
Strait Islander children and will inform global vaccine policy for other high rotavirus burden settings.
Date of Award2023
Original languageEnglish
SupervisorAnna Ralph (Supervisor), Thomas Snelling (Supervisor) & Peter Morris (Supervisor)

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