COVID-19 vaccine hesitancy and vaccine passports: a cross-sectional conjoint experiment in Japan

Objectives While the development of vaccines against the Novel Coronavirus (COVID-19) brought hope of establishing herd immunity and ending the global pandemic, vaccine hesitancy can hinder the progress towards herd immunity. In this study, by analysing the data collected when citizens undergo public health restrictions due to the pandemic, we assess the determinants of vaccine hesitancy, reasons for hesitation and potential effectiveness of vaccine passports used to relax public health restrictions on mitigating vaccine hesitancy. Design Cross-sectional study, longitudinal study and conjoint experimental design. Setting An online survey conducted in Japan in July 2021. Participants A demographically representative sample of 5000 Japanese adults aged 20-74. Primary outcome measures COVID-19 vaccination intention Results We found that about 30% of respondents did not intend to get vaccinated or had not yet decided, with major reasons for vaccine hesitancy relating to concerns about the safety and side effects of the vaccine. In line with previous findings, younger age, lower socioeconomic status, and psychological and behavioural factors such as weaker COVID-19 fear were associated with vaccine hesitancy. Easing of public health restrictions such as travel, wearing face masks and dining out at night was associated with an increase in vaccine acceptance by 4%-10%. Moreover, we found that more than 90% of respondents who intended to get vaccinated actually received it while smaller proportions among those undecided and unwilling to get vaccinated did so. Conclusion With a major concern about vaccine safety and side effects, interventions to mitigate against these may help to reduce vaccine hesitancy. Moreover, when citizens are imposed with restrictions, vaccine passports that increase their freedom may be helpful to increase vaccination rates.