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. A Discrete Choice Experiment study was conducted among 871 Vietnamese online participants distributed using the snowball sampling method in 2022. Among participants, 87.4% had received or were waiting for a COVID-19 booster shot. However, the willingness to pay was low at $US 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. Participants who had children less than 18 years old in their homes infected with COVID-19 had a lower willingness to pay (OR = 0.54; 95% CI = 0.39; 0.74). The burden of medical expenses (OR = 0.33; 95% CI = 0.25; 0.45) and fear of vaccine (OR = 0.93; 95% CI = 0.86; 1.00) were the negative factors of the level of willingness to pay. 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. Most importantly, all interventions should be conducted with informational transparency to strengthen trust between the public and authorities.