Predictors of willingness to use an HIV vaccine among gay, bisexual, and other men who have sex with men, and transgender and non-binary persons: evaluating the role of vaccine confidence, altruistic motivations, social concerns, and conspiracy belie

Globally, LGBTQIAPN+ individuals experience significant health disparities and variable vaccine uptake, influenced by medical distrust, marginalization and discrimination. This study explored of willingness to use a hypothetical HIV vaccine among men who have sex with men, transgender and non-binary persons in Brazil. A cross-sectional, web-based survey recruited participants via dating applications and social media from July to December 2021. Beyond demographic and behavioral information, the following instruments were used: the Vaccine Confidence Index, Vaccine Conspiracy Belief scale, and two other scales that measured altruistic motivations and social concerns. Willingness was assessed with the question “Would you use a vaccine against HIV (to prevent HIV acquisition)?” and the 4-point Likert-type scale responses were dichotomized into “No” which included “extremely unlikely”, “unlikely”, and “likely”, and “Yes” which included “extremely likely”. Logistic regression models were used to estimate associations between factors and willingness to vaccinate. Out of 3337 participants (97.7% cisgender men, 97.1% reported sex with men), 2562 (76.8%) expressed willingness to use a hypothetical HIV vaccine. Final model results indicated that higher perceived risk of HIV (adjusted odds ratio per 1 standard deviation increase [aOR/1SD]:1.13, 95% confidence interval [95%CI]:1.02–1.26), perceived vaccine effectiveness (aOR/1SD:1.15, 95%CI:1.02–1.29), altruistic motivations (aOR/1SD:2.41, 95%CI:2.18–2.68), and social concerns (aOR/1SD:1.37, 95%CI:1.24–1.52) were independently associated with increased vaccine willingness. Conversely, stronger vaccine conspiracy belief (aOR/1SD:0.89, 95%CI:0.80–0.99) was associated with decreased willingness to vaccinate. These findings underscore the importance of addressing vaccine conspiracy beliefs and promoting altruistic motivations in public health strategies to enhance vaccine uptake.