This is a follow-up study to the study pre-registered as: Petersen, M., Bor, A., & Jørgensen, F. J. (2020, October 14). Vaccine transparency and conspiracy beliefs. Retrieved from osf.io/9gr4a. The aim of the present study is to improve the previous study by... (1) Including a neutral baseline condition to assess how the effects of vague and transparent information differ compared to default perceptions. (2) Assessing the experimental effects of vague and transparent vaccine information on directly measured rates of vaccine acceptance. (3) Assessing the experimental effects of vague and transparent vaccine information on endorsement of conspiracy-related statements with a revised design that assesses these effects as main effects rather than interaction effects and, hence, increases the statistical power. (4) Assessing whether the association between conspiracy beliefs (measured in the form of individual differences in conspiratorial mentality and political cynicism), on the one hand, and specific vaccine acceptance, on the other hand, decreases when exposed to transparent (vs vague) vaccine information. This analytical approach seeks to circumvent the practical and ethical challenges of inducing conspiracy mindsets experimentally. (5) Assessing the experimental effects of vague versus transparent vaccine information on trust in national health authorities to access potential second-order benefits of transparent communication. (6) Testing two alternative individual differences as predictors of vaccine acceptance and conspiracy-endorsements: Trust in science and tolerance for ambiguity (in addition to conspiratorial thinking and political cynicism). (7) Validating the content of an ostensibly conspiracy-related statement used in the previous study.