Transcript Microsoft PowerPoint - Department of Agriculture and Fisheries

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.
Hendra virus background
Vaccine implementation
 Hendra virus (HeV): zoonotic disease of sporadic occurrence in Australia
 caused by HeV spill over from flying foxes to horses and from horses to
people
 since 1994 71 confirmed equine and seven human cases with the five
most recent human cases all occurring in veterinary health professionals
 high case fatality rate (75% in equines, 57% in humans)
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.
Hendra virus vaccine
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.
Vaccine uptake and barriers to uptake
In 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.
abc.net.au
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.
Methodology
Data 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.
Core questions (repeated across surveys)
Supplementary questions (topical issues arising)
Recruitment
Start
S1
6 months
S2
12 months
S3
18 months
S4
24 months
S5
30 months
Consolidation
36 months
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.”
Conclusions
Although 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.
The 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.
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