Hendra virus (HeV): zoonotic disease of sporadic occurrence in Australia caused by HeV spill over from flying foxes to horses and from horses to peoplesince 1994 71 confirmed equine and seven human cases with the five most recent human cases all occurring in veterinary health professionalshigh case fatality rate (75% in equines, 57% in humans)Novel vaccine acceptance in emerging infectious diseases: a case study of Hendra virus vaccine uptake in Australia

M. Taylor1, A. Wiethoelter1,2, N. Schembri1, J-ALML. Toribio2, N. Dhand2, N. Kung3, B. Moloney4, T. Wright4 & H. Field5.

1University of Western Sydney, Centre for Health Research, 2The University of Sydney, Faculty of Veterinary Science, 3Queensland Department of Agriculture and Fisheries, 4NSW Department of Primary Industries, 5Ecohealth Alliance.hhalter@uws.edu.auHendra virus backgroundVaccine implementationData presented here are part of the Horse owners and Hendra virus: A Longitudinal cohort study To Evaluate Risk (HHALTER) project. This study aims to explore and track changes in knowledge, attitudes, and practices of a national cohort of horse owners followed over a two-year period (from Nov 2012 Nov 2014) via five self-administered online surveys at six-monthly intervals (see study structure below). The HHALTER study also includes a series of in-depth interviews with horse owners.

A super cluster of HeV cases in New South Wales and Queensland in 2011 triggered public outcry. This was followed by funding which enabled the fast-tracking of HeV research, including the development of a novel vaccine for horses. In November 2012 the vaccine became available, providing a tool to break the transmission pathway to horses and people. MethodologyIn total 1,449 horse owners have taken part in one or more surveys, with a cohort of 341 completing all five surveys. Data presented are from this cohort group only.The figure below shows the vaccine uptake in the cohort over the two year study period. Uptake rose from around 12% shortly after launch to over 60% two years later.

Horse owners, who decided not to vaccinate, reported that their decision was very much or extremely affected by the high cost of vaccination (60%), a perceived low HeV risk in their area (49%), for their horses (44%) and for themselves/their families (40%) as well as concerns about adverse reactions of the vaccine (28%). As one survey respondent commented: The decision came down to the risk to our area being affected. As the vaccine was rushed to market without proper testing, I felt that the risk of side effects was greater than the risk of Hendra.ConclusionsAlthough vaccine uptake in the HHALTER study cohort group has risen steadily over the two year period, the overall national rate of HeV vaccination uptake is estimated to be less than 10%. Despite being provided with a safe and effective vaccine for Hendra virus that can protect horses and break the transmission cycle of the virus to humans, many Australian horse owners have been reluctant to commit to it. General issues pertinent to novel vaccines, combined with challenges in the implementation of the vaccine have led to issues of mistrust and misconception with some horse owners. Moreover, factors such as cost, booster dose schedules, complexities around perceived risk, and ulterior motives attributed to veterinarians have only served to polarise attitudes to vaccine acceptance.Hendra virus vaccineThe University of Western Sydney was contracted by the Rural Industries Research and Development Corporation to undertake this research project. This research was funded by the Commonwealth of Australia, the State of New South Wales and the State of Queensland under the National Hendra Virus Research Program. The vaccine was launched ahead of schedule and without pre-launch consultation with the Australian horse industry. Instead of being registered as a chemical product, it was released under a Minor Use Permit due to limited time for testing. This necessitated a number of restrictions, most notably, that the vaccine must be administered by a registered and accredited veterinarian. The vaccine schedule requires an initial dose, followed by a second dose 21-42 days later, and then a booster every six months. Vaccinated horses have to be microchipped for identification and their vaccination status is recorded on a national database. The booster schedule must be maintained for horse owners to hold a valid vaccination certificate mandatory for some equine events in Australia.

abc.net.auVaccine uptake and barriers to uptake

Chart1

11.8Nov 2012

21.94.6

41.614.2

4117.3

43.616.5

Vaccinated - all horses

Vaccinated - some horses

%

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Vaccinated - all horsesVaccinated - some horses

Nov 201212

May 2013225

Nov 20134214

May 20144117

Nov 20144417

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Vaccinated - all horses

Vaccinated - some horses

%

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