1. Introduction
Vaccination is considered one of the most important measures of preventing and controlling both human and animal diseases. The success of every vaccination campaign is based on the vaccine characteristics such as its efficacy and safety and on vaccination coverage and compliance, which depend on human behaviour. The social-psychological factors influencing vaccination compliance have been widely studied, both in human medicine (e.g., Brewer et al., 2017; Chapman & Coups, 1999; Ratnapradipa et al., 2017; Schmid et al., 2017 & Wheelock et al., 2013) and animal medicine (e.g., Elbres et al., 2010; Eschle et al., 2020 & Gehrig et al., 2019). However, to our knowledge, investigation of the change of vaccination compliance through time (compliance dynamics) and the factors influencing it was never published. Such information is of primary importance, first for policymakers who wish to decide if vaccination against a certain disease should be mandatory or voluntary. Second, these data are essential for planning better intervention programs to prevent deterioration of vaccination compliance.
To provide this information, we investigated the dynamics of Israeli dairy farmers’ vaccination compliance against Lumpy Skin Disease (LSD), a vector-borne viral disease. We chose LSD as it is considered one of the most significant diseases affecting cattle. LSD is caused by the lumpy skin disease virus (LSDV), a member of the Poxviridae family and the genus Capripoxvirus (Tuppurainen & Oura, 2012). The disease is mostly characterized by the occurrence of localized or generalized skin nodules. It is often accompanied by lethargy, reduced appetite, edema, reduction in milk production, and might even cause death (Tuppurainen & Oura, 2012). Until 2012, LSD was mainly limited to Africa with some sporadic incursions which caused epidemics in the Middle-East. From 2012, the disease had spread to Israel, Turkey, Greece, Bulgaria and other Balkan countries, Armenia, Azerbaijan, Kazakhstan, Georgia, the Russian Federation, China, India, Bangladesh, Syria, Cambodia, Hong-Kong, Malaysia, Vietnam, and Thailand (EFSA, 2017; EFSA, 2019 & OIE website).
The effectiveness of the Neethling vaccine used in Israel against LSD was demonstrated beyond any doubt (Ben-Gera et al., 2015 & Klement et al., 2018). But the vaccination strategy, determined by the policymakers, varied. Five LSD epidemics occurred in Israel. The largest occurred in 2012 and lasted until August 2013. Thereafter, compulsory vaccination was implemented by the Israeli Veterinary Services (IVS). In June 2016, the IVS changed its policy and vaccination against LSD became voluntary. In 2019, a new epidemic of LSD occurred in Israel. These events allowed us to explore the dynamics of voluntary vaccination compliance among Israeli farmers and their relation to the occurrence of LSD.
For this purpose, we followed the annual vaccination compliance between 2016-2019 among a cohort of 566 Israeli dairy farmers insured by ‘Hachaklait’ (a veterinary cooperation, owned by the farmers, which provides veterinary services to about 80% of the dairy farms in Israel). In addition, we investigated the demographic and social-psychological factors influencing vaccination compliance among 90 dairy farmers using predefined questionnaires based on the theory of planned behaviour (TPB), a reasoned action approach. Theories of reasoned action and planned behaviour are widely used in the study of medical behaviours (Albarracin et al., 2001; McEachan et al., 2016 & Sok et al., 2021), including the motivation to vaccinate (Jozkowski & Geshnizjani, 2016 & Sok et al., 2015).
The TPB predicts that a given future behaviour is explained by the intention to perform it. The intention is directly explained by three main constructs: attitude (A) (the person’s favourable or unfavourable evaluation of the behaviour), subjective norms (SN) (the social pressures a person perceives to perform or not the behaviour) and perceived behavioural control (PBC) (the perceived own capability to perform that behaviour) (Ajzen, 1985). Further on, Fishbein and Ajzen developed the conceptualization of the TPB’s predictors of intention and defined two distinguishable subdimensions to the existing unitary definition of attitude (instrumental, experiential) and perceived behavioural control (autonomy, capacity). Regarding the subjective norms, a distinction between injunctive and descriptive aspects was made (Fishbein & Ajzen, 2009). Injunctive norms refer to people’s perceptions of what others would like them to do or what is expected of them. Descriptive norms refer to people’s perceptions of what important others do.
The results of this study point to the major factors that influence both vaccination compliance and compliance deterioration. This reflects on the potential effectiveness of strategies to increase vaccination compliance.