AimTo identify psychosocial predictors of the intention to get a booster COVID-19 vaccine in a low-income country, given that increasing booster vaccination rates against COVID-19 remains a global challenge, especially among low- and middle-income countries (LMIC).Subject and methodsWe used an online survey to collect responses from a non-probabilistic sample of 720 Bolivians regarding vaccine uptake, motives, perceived confidence, information sources, attitudes favouring COVID-19 vaccines, biosafety behaviour, and sociodemographic characteristics. Descriptive, bivariate, and multivariate analyses were performed to identify significant associations and predictors.ResultsWe found that having already received the third dose, obtaining recommendations from family or friends, recommendation from the government, perceived confidence in the previously received dose, and higher attitudes in favour of COVID-19 vaccines significantly predicted the intention to get a booster dose. The associations were significant even when adjusting the model for sociodemographic variables.ConclusionIncluding certain psychosocial factors could enhance the promotion of voluntary booster doses among residents of low- and middle-income countries such as Bolivia, where cultural, social, political, and contextual variables may influence health behaviour and increase health-associated risk factors.