What Determines Vaccine Hesitancy: Recommendations from Childhood Vaccine Hesitancy to Address COVID-19 Vaccine Hesitancy

"Understanding the factors that affect vaccine hesitancy will aid in addressing hesitancy and, in turn, lead to an increase in vaccine uptake."

The COVID-19 pandemic has brought heightened attention to the ongoing, persistent issue of vaccine hesitancy. In many countries, even when policies, financing, and resources are in place and services are available, a large number of children still fail to complete immunisation schedules. And a 2021 systematic review of COVID-19-related vaccine hesitancy globally found wide variation between countries, with the overall acceptance rate below 70%. This article draws on insights from previous literature to determine what works to increase vaccine uptake and how to apply this knowledge to increase COVID-19 vaccine uptake. It creates and presents a conceptual model of indicators that influence vaccine uptake for health providers and caregivers, which can also be used for vaccine recipients.

Two of the authors conducted a literature review of peer-reviewed articles and extracted 117 articles that address vaccine hesitancy and uptake, measurement tools, and quality of service between the health provider and caregiver. The literature review specifically included looking for sets of tools that incorporate direct data collection with providers and caregivers, finding 91 tools that showcase provider and caregiver characteristics. In developing a conceptual model informed by 15 core articles, the researchers consulted with professionals from 23 countries in the Europe and Central Asia Region who were taking part in capacity-building workshops. These meetings served as a form of validation for the conceptual model constructs through discussions and feedback based on research and personal experience.

The final model combines three existing vaccination models: the World Health Organization (WHO) Increasing Vaccination Model, the Strategic Advisory Group of Experts (SAGE) Vaccine Hesitancy Determinants Matrix, and the United Nations Children's Fund (UNICEF)'s Journey to Immunization. The core strength of these models is that they illustrate causal factors associated with vaccine hesitancy. However, each of them has various shortcomings, which the paper outlines. One insight to emerge from the analysis of the models is the importance of frontline workers (FLWs) and interpersonal communication and counseling (IPC/C). For example, UNICEF has found that a key determinant of vaccine hesitancy is linked to the quality of communication between health workers and clients, and WHO notes that FLWs are seen as influencers and trusted sources of information on vaccines. Questions and concerns regarding childhood vaccinations and COVID-19 vaccinations can relate to side effects, ingredients, and number of doses. Therefore, FLWs must be trained and supported to provide accurate information and support to patients. Recommendations from a FLW may increase confidence, set a social norm, or showcase a direct behaviour change method.

The overarching goal of the final conceptual model (see above), which is intended to be adaptable to local contexts, is to improve demand for and equitable delivery of immunisation services, with a focus on increased access to and demand for immunisation services. The purpose of this model is not to provide a holistic picture but to measure specific intermediate outcomes (indicators), which can then be directly linked to the intention to vaccinate. The impact of reducing vaccine hesitancy is measurable through improved vaccination uptake and subsequent declines in the incidence of vaccine-preventable diseases. While this is the long-term view of the process, several proximal factors contribute to the reduction in vaccine hesitancy. For example, upstream factors include the communication and media environment, policies and laws, and facilities and supplies.

This model specifically focuses on provider and caregiver/vaccine recipient factors that influence the intention to vaccinate. This outcome is achievable through a series of related steps. Although most constructs are standalone, some constructs for providers are multidimensional and cannot be directly measured. For example, the broader topic of affective counseling by providers is measured through empathy, active listening, cultural competence, and IPC. Combining these questions can help create an affective counseling scale measure, which can then be correlated with other constructs.

The constructs under the caregivers' box in the conceptual model showcase the levels of the socio-ecological model (SEM). Individual-level constructs include attitudes, perceived threat, social norms, perceived behavioural control, decision-making, complacency, confidence, counseling satisfaction, and IPC; community-level constructs include trust in providers, caregiver vulnerability, sources of information, misleading information, and community responsibility; and societal-level constructs include convenience and the right to vaccination.

The researchers suggest that most of the constructs in the conceptual model can be adapted to COVID-19 vaccinations, noting that:

• A primary difference is that instead of only deciding whether to vaccinate their child, individuals also decide for themselves.
• Given the setting, organisational needs, or health provider needs, the provider constructs in the conceptual model will vary in how they interact and their relevance for COVID-19 vaccination. "However, regardless of where the vaccine is being administered or how much time the health provider has to administer the vaccine, the provider should always be empathetic, respectful, actively listening to the vaccine recipient, culturally competent, and be able to engage in interpersonal communication."
• Depending on the setting, the constructs for caregivers or vaccine recipients will also vary in relevance for COVID-19 vaccination. But core factors apply - e.g., the vaccine recipient needs to have confidence in the effectiveness and safety of vaccines, the system delivering them, the proficiency of the health providers, and the motivations of the leaders and policymakers.
• The conceptual model's constructs can also be applied to address health provider vaccine hesitancy, which "varies by behavioral, social, and other contextual factors. Health providers' confidence in the vaccines, knowledge, and whether they feel a responsibility to protect and promote the public's health versus personal autonomy influence their vaccine behaviors and choices..."

The researchers argue: "It is imperative to train health workers and provide them with the skills and techniques to interact with vaccine-hesitant colleagues, caregivers, and vaccine recipients to increase vaccination uptake..." In their estimation, the core-provider characteristics included in the model can be used to develop role-model provider portfolios for vicarious learning and can be included in training to build the capacity of FLWs. The caregiver or vaccine recipient characteristics can be used to develop tailored training interventions for different categories of audiences based on the specific constructs that need to be addressed. There must also be a monitoring and evaluation framework in place to determine the efficacy of such training.

Per the researchers, the next step is to develop, and then to pilot, measurement tools based on the construct definitions so that the scope and scale of vaccine hesitancy issues can be assessed by vaccine type and context. A tool that can be adapted globally would be ideal; they assert that the conceptual model will allow for the necessary modifications.

Overall, this article concludes that the reasons for vaccine hesitancy are complex; therefore, a multifaceted approach, guided by the model presented herein, is needed to understand and then to address it. In that light, the paper "is intended to assist with future design, implementation, monitoring, and evaluation. The definitions compiled here [see Tables 1 and 2 in the paper] can be used for designing new interventions, training health providers, supplementing existing efforts, or for routine monitoring and evaluation purposes. Discrete models tailored to various factors and determinants within local contexts can guide health care workers as well as public health experts in their process."

Ultimately, caregivers, vaccine recipients, and FLWs "must work together to increase the uptake of vaccinations to protect themselves and, in turn, protect their communities."