University of Cambridge The clear and transparent communication of COVID-19 vaccines risks and benefits has been suggested as an approach to increasing vaccine uptake among the general public ., a means of maintaining public trust in science., and also as an ethical imperative. A sizable minority of people around the world express hesitancy towards taking COVID-19 vaccines. Concerns over safety and efficacy may be fuelled by COVID-19 vaccine misinformation. Many public health commentators and researchers have called for transparent communication of COVID-19 vaccine information to improve vaccine uptake. Vaccinations do not offer full immunity, which creates a dilemma for communicators who wish to be transparent about benefits and harms and encourage continued caution in vaccinated individuals but not undermine confidence in vaccination. In order to inform debates about how to boost uptake, researchers conducted two experiments to generate empirical data on the effects of real-w