[Vaccine hesitancy: current status, associated factors, measurement, and approach]

Definition and present status　Vaccine hesitancy, defined as "delay in acceptance or refusal of vaccination despite availability of vaccination services," is a global public health concern. Specifically, COVID-19 and human papillomavirus (HPV) vaccine hesitancy remains a major social challenge in Japan, and effective preventive strategies are urgently required. In this review, we discuss previous studies that have described vaccine hesitancy.Associated factors　Vaccine hesitancy is affected by several factors, primarily psychological variables (referred to as the "3Cs" comprising confidence, complacency, and convenience regarding individuals' perceptions of vaccination) and sociodemographic variables (age, sex, socioeconomic status, race, and social capital). "Behavioral and Social Drivers of Vaccination Framework", developed recently by the World Health Organization, has focused on vaccination-specific beliefs and reports that programs may affect and are likely to have wide applicability in the development of effective interventions.Measurement　Identification of psychological factors associated with vaccination hesitancy is important to establish strategies to increase vaccine uptake. Many scales are available to measure vaccine hesitancy and psychological factors that affect vaccine hesitancy. These scales include different evaluation items, validity, reliability, and availability of validated Japanese versions. Therefore, careful selection of scales based on their intended purpose and the target population in whom the desired intervention is intended are important. A representative 7C scale is widely used globally. It has been translated into more than 10 languages, including Japanese.Approach　Several studies and articles, mainly developed for the European and American populations provide guidelines for selection of evidence-based strategies and interventions to increase vaccine uptake. Evidence-based strategies may be broadly classified into the following categories: (1) Strengthening the healthcare system through implementation of the principles of behavioral science. (2) Development of tailored approaches using systematic listening activities. (3) Provision of evidence-based resources to support healthcare personnel. (4) Utilization of media. Based on findings described by previous studies discussed in this report, it may be important to plan strategies to improve the uptake of each vaccine in Japan, such as those for COVID-19, HPV, and also childhood vaccines.