ABSTRACT
BackgroundThe quality of evidence about the effectiveness of non-pharmaceutical health interventions is often low, but little is known about the effects of communicating indications of evidence quality to the public. MethodsIn two blinded, randomised, controlled, online experiments, US participants (total n=2140) were shown one of several versions of an infographic illustrating the effectiveness of eye protection in reducing COVID-19 transmission. Their trust in the information, understanding, feelings of effectiveness of eye protection, and the likelihood of them adopting it were measured. FindingsCompared to those given no quality cues, participants who were told the quality of the evidence on eye protection was low, rated the evidence less trustworthy (p=.001), and rated it as subjectively less effective (p=.020). The same effects emerged compared to those who were told the quality of the evidence was high, and in one of the two studies, those shown low quality of evidence said they were less likely to use eye protection (p=.005). Participants who were told the quality of the evidence was high showed no significant differences on these measures compared to those given no information about evidence quality. InterpretationWithout quality of evidence cues, participants responded to the evidence about the public health intervention as if it was high quality and this affected their subjective perceptions of its efficacy and trust in the provided information. This raises the ethical dilemma of weighing the importance of transparently stating when the evidence base is actually low quality against evidence that providing such information can decrease trust, perception of intervention efficacy, and likelihood of adopting it. FundingThe Winton Centre for Risk & Evidence Communication, thanks to the David & Claudia Harding Foundation O_TEXTBOXResearch in ContextO_ST_ABSEvidence before this studyC_ST_ABSThis is the first quantitative, empirical study, to our knowledge, on the effects of communicating the quality of evidence underlying an effectiveness estimate of a public health intervention on a public audience. Added value of this studyThis study provides novel insights into the effects of quality of evidence communication in a public health context. It is thus of high theoretical as well as translational value. Implications of all the available evidenceMembers of the public may assume that information around the effectiveness of a measure such as wearing eye protection to protect against COVID-19 are based on high quality evidence if they are given no cues to suggest otherwise. Yet, when given a statement of the quality of the evidence, this can (appropriately) affect their feelings of the trustworthiness of the information and their subjective judgement of the effectiveness of the measure. This raises the issue of whether there is an ethical imperative to communicate the quality of underlying evidence, particularly when it is low, albeit with the recognition that this may reduce uptake of a public health measure. C_TEXTBOX
ABSTRACT
The success of mass COVID-19 vaccination campaigns rests on widespread uptake. However, although vaccinations provide good protection, they do not offer full immunity and while they likely reduce transmission of the virus to others, the extent of this remains uncertain. This produces 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 an important public health measure. In two large pre-registered experimental studies on quota-sampled UK public participants we investigate the effects of providing transparent communication--including uncertainty--about vaccination effectiveness on decision-making. In Study 1 (n = 2,097) we report that detailed information about COVID-19 vaccines, including results of clinical trials, does not have a significant impact on beliefs about the efficacy of such vaccines, concerns over side effects, or intentions to receive a vaccine. Study 2 (n = 2,217) addressed concerns that highlighting the need to maintain protective behaviours (e.g. social distancing) post-vaccination may lower perceptions of vaccine efficacy and willingness to receive a vaccine. We do not find evidence of this: transparent messages did not significantly reduce perceptions of vaccine efficacy, and in some cases increased perceptions of efficacy. We again report no main effect of messages on intentions to receive a vaccine. The results of both studies suggest that transparently informing people of the limitations of vaccinations does not reduce intentions to be vaccinated but neither does it increase intentions to engage in protective behaviours post-vaccination.
ABSTRACT
Understanding the drivers of vaccine acceptance is crucial to the success of COVID-19 mass vaccination campaigns. Across 25 national samples from 12 different countries we examined the psychological correlates of willingness to receive a COVID-19 vaccine (total N = 25,334), with a focus on risk perception and trust in a number of relevant actors, both in general and specifically regarding the COVID-19 pandemic. Male sex, trust in medical and scientific experts and worry about the virus emerge as the most consistent predictors of reported vaccine acceptance across countries. In a subset of samples we show that these effects are robust after controlling for attitudes towards vaccination in general. Our results indicate that the burden of trust largely rests on the shoulders of the scientific and medical community, with implications for how future COVID-19 vaccination information should be communicated to maximize uptake.
