Vaccination Hesitancy: Fear, Trust, and Exposure Expectancy of an Ebola Outbreak

The World Health Organization (WHO) listed both vaccine hesitancy and Ebola among the top 10 threats to global health in 2019. With regard to the former, the long history of vaccination has been characterised by hesitancy or refusal to be vaccinated in many countries and in many cases of disease, including polio, pertussis, measles, and tetanus. With regard to the latter, the context of this study was a situation in which the United States (US) was: (i) largely aware of the lethal Ebola Virus Disease (EVD) outbreak in Africa; (ii) aware that some cases had shown up in the US; and (iii) concerned that a large Ebola outbreak could follow in the absence of an imminent prospect of immunisation.

In addition to being informed by previous research on vaccine hesitancy, the present study draws on 2 related theoretical models:

1. Social Cognition Theory (SCT): Rooted in the work of Albert Bandura (1986), SCT holds that in matters of health behaviour, there is reciprocal triadic causation among 3 basic components: behaviour, person, and environment. The model predicts that as the environment is changed by the locational intrusion of a disease outbreak, the individual's coping behaviour responds and is changed. The coping behaviour examined in this study is the decision to accept or not to accept the prospective Ebola vaccine.
2. Protection Motivation Theory (PMT): Basic PMT theory states that the individual's intent to adopt a response to a threatening situation is formed by: the perceived magnitude of the threat; the probability of the threat's occurrence; and the efficacy of the coping response. PMT suggests that willingness to accept a vaccine is influenced by the degree of fear the respondent carries toward the disease and the perceived likelihood of its nearby outbreak. Willingness also is affected by the respondent's confidence in the efficacy of the government to successfully prevent a nationwide epidemic of Ebola.

The study's authors conducted a secondary analysis of data from a 2014 CNN/ORC poll, conducted during the 2014 Ebola outbreak. The poll asked a random selection of 1,018 adults if they would take an Ebola vaccine if and when it became available, along with other questions about participants' levels of generalised fear, trust in the government, and expectancy of being exposed to Ebola.

Increased receptivity to vaccines was associated with not just fear of Ebola, but with a more generalised fear about current events in the US. People who trusted the US government to prevent an Ebola outbreak were also more likely to say they would take the vaccination. Eighty percent of participants thought it was somewhat or highly likely that the US would have an Ebola outbreak fairly soon. The closer they believed the outbreak could occur to their own community, the more likely they were to accept the vaccine.

The SAGE Working Group on Vaccine Hesitancy has suggested that there are 3 major domains of variables that influence vaccine hesitancy: convenience or the ease of access, confidence or trust in the safety or efficacy of the vaccine, and complacency or risk of disease and importance of immunisation. The researchers see these elements reflected in the findings, seeing convenience in the fact that 48% of the sample is willing to take the Ebola vaccination even though its future degree of convenience is undetermined, confidence in the 73% of the sample willing to trust the government's ability to deal with an Ebola outbreak, and complacency in the 76% of the sample who doubt that a resident of their community will become infected with Ebola.

Each of this study's 3 hypotheses is supported by the data - that is, willingness to take a prospective Ebola vaccine is related: to a generalised sense of fear, to trust in the federal government's ability to prevent an outbreak, and to the extent to which an Ebola outbreak is anticipated to occur in the local environment.

This paper introduces 2 operational measures not normally found in studies of vaccine hesitancy:

• Fear: Respondents were asked if they were "scared" about "...the way things are going in the country today". The researchers contend that "scared" carries a stronger connotation of fearfulness than is commonly measured and therefore more likely to be motivational and reflected in engagement in health protective behaviour.
• Expectancy of disease exposure: This study used a geographically wider measure of expectancy than is commonly reported, constructing a new 3-item Exposure Expectancy Scale (alpha = 0. 635): "outbreak in US", "outbreak in the nearby city", and "outbreak in family".

The researchers note that, since the data were collected, progress has been made in development of a preventive vaccine for the disease. They contend that "a re-examination of the research question is in order. That is, do fear, trust, and exposure expectancy relate in the same manner in the US population today as vaccine is soon to become available as they did in 2014 when vaccine was not available? Would having vaccine on hand make a greater willingness of respondents to take the vaccine?"

A concluding thought the researchers offer is that it is important to investigate how people incorporate the image of disease in general and Ebola in particular into their understanding of daily life events. This understanding influences their general fear response to the contagious outbreak, to the trust they hold in responding institutions, and to the behavioural coping mechanism they employ.