A systematic review of interventions for reducing parental vaccine refusal and vaccine hesitancy

Highlights

• Unvaccinated individuals put communities at risk of disease.

• Parental vaccine refusal and hesitance is an emerging issue.

• We conducted a systematic review for interventions to reduce refusal/hesitance.

• We found limited evidence on effective strategies to guide policy makers.

• There is a need for appropriately designed, executed and evaluated intervention studies.

Abstract

Unvaccinated individuals pose a public health threat to communities. Research has identified many factors associated with parental vaccine refusal and hesitancy toward childhood and adolescent immunizations. However, data on the effectiveness of interventions to address parental refusal are limited. We conducted a systematic review of four online databases to identify interventional studies.

We used criteria recommended by the WHO's Strategic Advisory Group of Experts on immunization (SAGE) for the quality assessment of studies. Intervention categories and outcomes were evaluated for each body of evidence and confidence in overall estimates of effect was determined. There is limited evidence to guide implementation of effective strategies to deal with the emerging threat of parental vaccine refusal. There is a need for appropriately designed, executed and evaluated intervention studies to address this gap in knowledge.

Introduction

The success of vaccines in reducing disease-associated mortality is second only to the introduction of safe drinking water [2]. According to estimates by the World Health Organization, vaccines for diphtheria, pertussis, tetanus, and measles save between two and three million lives every year. The continued success of vaccines relies on adequate immunization coverage which in turn requires parental willingness to vaccinate children. There has been an increase in concerns about real or perceived vaccine adverse events among parents in the developed world making them uneasy about the decision to vaccinate their children, described as ‘vaccine hesitancy’ in the literature [3], [4]. This is one of the reasons that may lead parents to seek alternative or delayed vaccination schedules, or they may refuse vaccinations altogether. Individuals who remain unvaccinated put communities at risk of disease outbreaks [5], [6]. Although a large body of literature has called for increasing vaccination rates among parents who refuse to vaccinate their children [5], [6], [7], [8], [9], [10], [11], there is a dearth of studies that evaluate interventions to achieve this goal.

Over the past few years, there has been a paradigm shift in the developed world from efforts to increase access to immunizations, to improving their uptake. With regards to the particular issue of vaccine refusal, many studies have explored parents’ attitudes toward immunization [12], [13], their sources of information [14] for decision making, and their reasons for refusing childhood immunizations. Parents’ beliefs about the contraindications and perceived dangers of immunization contribute to their unwillingness to expose healthy children to inoculums [15], [16], [17], [18]. Research studies on cognitive decision making processes report that parents prefer the risks of errors of omission (contracting a disease naturally) over the risks of errors of commission (suffering from vaccine adverse events) [17], [19]. Parents may also believe that they can control their child's susceptibility to a disease and its outcome [17]. In addition, some parents who are opposed to conventional medicine believe that it is more beneficial for children to recover from diseases than receive vaccines for them [20]. Parents may also refuse on religious grounds [18] or because they hold ethical objections to state laws that mandate vaccines [21]. Despite the existence of this vast knowledge base to help us understand parental concerns, there are few comprehensive and systematic reviews on effective interventions for reducing parental vaccine refusal. We therefore conducted a systematic review to amass and evaluate the literature on interventions to decrease parental vaccine refusal and hesitancy toward recommended childhood and adolescent vaccines.