Regular COVID-19 booster shot preference and willingness to pay in the Vietnamese population: a theory-driven discrete choice experiment (Preprint)

BACKGROUND The COVID-19 booster vaccination rate has declined despite the wide availability of vaccines. As COVID-19 is becoming endemic and the introduction of charges for regular booster vaccination, measurement of public acceptance and willingness to pay for regular COVID-19 boosters is ever more crucial. This study investigated the Vietnamese population’s willingness to receive and pay for the COVID-19 booster vaccine, as well as identified factors correlated with vaccine hesitancy during the critical preparation phase for new booster policies. OBJECTIVE This study aims to 1) investigate public acceptance for regular COVID-19 boosters, 2) assess willingness to pay for a COVID-19 booster shot, and 3) identify factors associated with vaccine hesitancy. Our results provide crucial insights and implications for policy response as well as the development of a feasible and effective vaccination campaign, during Vietnam's waning vaccine immunity period. METHODS A cross-sectional study was conducted among 871 Vietnamese online participants from April 2022 to August 2022. An online questionnaire based on the Discrete Choice Experiment design was developed, distributed using the snowball sampling method, and subsequently conjointly analyzed on the Qualtrics platform. History of COVID-19 infection and vaccination, health status, willingness to vaccinate, willingness to pay, and other factors were examined. RESULTS Among participants, 87.4% had received or were waiting for a COVID-19 booster shot. However, the willingness to pay was critically low at $USD 8, and most participants indicated an unwillingness to pay (25.8%) or willingness to pay for only half of the vaccine costs (25.4%). While information insufficiency and wariness towards vaccines were factors most associated with the unwillingness to pay, long-term side effects, immunity duration, and mortality rate were the attributes most concerned with during the vaccine decision-making period. Meanwhile, the sense of responsibility to the community, workplace (0.7306), and national disease prevention (0.7332) were the most heavily weighted drivers of vaccine uptake. CONCLUSIONS Significant inconsistency between high acceptance and low willingness to pay underscores the role of vaccine information and public trust. In addition to raising awareness about the most concerning characteristics of the COVID-19 booster, social media, and social listening should be utilized in collaboration with health professionals to establish a two-way information exchange. Work incentives and suitable mandates should continue in order to encourage workforce participation. Most importantly, all interventions should be conducted with informational transparency to strengthen trust between the public and authorities.