Introduction
Hendra virus (HeV; genus Henipavirus , familyParamyxoviridae ) is an emerging zoonotic virus carried by four
species of Pteropus bats in Australia (Annand et al., 2022;
Middleton et al., 2014). Transmission of HeV to horses is considered to
be predominantly from P. alecto (Annand et al., 2022; Edson et
al., 2019) and infected horses are the primary source of infection for
people (Middleton et al., 2014; Yuen et al., 2021). Sixty-six spillover
events between bats and horses have been recorded, resulting in 108
horse deaths and seven reported human infections including four deaths
(Annand et al., 2022; Business Queensland, 2021; NSW Health, 2022).
There have also been two reported cases of HeV infected dogs (Field,
2016).
The risk of HeV disease (HeVD) in horses is expanding geographically.
Cases have recently been reported as far south as Scone (Business
Queensland, 2021; Yuen et al., 2021) and West Wallsend, New South Wales,
in 2021 (J. Taylor et al., 2022). The latter case occurred beyond the
previously described P. alecto distribution of eastern coastal
Queensland to northern New South Wales (Annand et al., 2022). A new
strain, HeVD-g2, for which the pathogenicity and prevalence inPteropus bats in Australia is unknown, has also recently been
detected in Queensland (Annand et al., 2022).
Therapeutics for the treatment of HeVD are not available; however, a
vaccine for horses and post-exposure prophylaxis for humans have been
developed (Annand et al., 2022; Middleton et al., 2014). Horses aged ≥4
months can be vaccinated (Zoetis Australia Pty Limited, n.d.), with two
doses given 3-6 weeks apart and a third dose six months later, then an
annual booster dose thereafter (Zoetis Australia Pty Limited, n.d.).
Despite the availability of the vaccine since 2012, the expanding risk
of HeVD, the high case fatality rate of HeVD in both horses and humans,
HeV vaccine uptake is as low as 17% in Queensland and 12% in New South
Wales risk regions (M. Taylor et al., 2016). As well as protecting
equine welfare, HeV vaccination of horses remains a priority to protect
public health (Degeling et al., 2018; Degeling & Kerridge, 2013).
The recent development of the Behavioural and Social Drivers of
Vaccination (BeSD) framework has demonstrated value in understanding and
promoting vaccine uptake by caregivers in the context of
vaccine-preventable childhood diseases (World Health Organization,
2022a, 2022b). In this framework, there are four measurable domains of
behavioural and social drivers in individuals that are potentially
changeable: (1) Thinking and Feeling , relating to cognitive and
emotional responses to vaccine-preventable diseases and vaccines,
including disease risk perception and vaccine confidence; (2)Social Processes , defined as the social experiences related to
vaccines, including gender equity, social norms about vaccination, and
receiving health worker recommendations to be vaccinated; (3)Motivation , influenced by the former two domains, and including
vaccination intention, willingness, and hesitancy; and (4)Practical Issues , which are people’s experiences when trying to
get vaccinated, including access barriers such as availability,
affordability, ease of access, quality of service, and respect from
health workers (WHO, 2022b). The combination of the four domains drives
or hinders uptake of recommended vaccines (WHO, 2022b). Given the
potential similarities between parents making vaccination decisions for
their children and horse owners deciding on vaccination for their
horses, the BeSD framework may be useful in helping to understand the
drivers of HeV vaccination.
The objective of this review was to collate information about
evidence-based communication interventions that have been used to
promote HeVD vaccine uptake by horse owners. We hypothesised that there
are few interventions; therefore, a secondary objective was to appraise
information in the reviewed records against the domains of the BeSD
framework as a preliminary assessment of the types of information
available about factors that drive or hinder HeVD vaccine uptake. This
review and assessment will inform research and development of a program
to promote HeVD vaccination.