Do interventions containing risk messages increase risk appraisal and the subsequent vaccination intentions and uptake? - A systematic review and meta-analysis.

purposeThere is good evidence that for many behaviours, increasing risk appraisal can lead to a change in behaviour, heightened when efficacy appraisals are also increased. The present systematic review addressed whether interventions presenting a risk message increase risk appraisal and an increase in vaccination intentions and uptake.

methodA systematic search identified randomized controlled trials of interventions presenting a risk message and measuring risk appraisal and intentions and uptake post-intervention. Random-effects meta-analyses investigated the size of the effect that interventions had on vaccination risk appraisal and on vaccination behaviour or intention to vaccinate, and the size of the relationship between vaccination risk appraisal and vaccination intentions and uptake.

resultsEighteen studies were included and 16 meta-analysed. Interventions overall had small significant effects on risk appraisal (d = 0.161, p = .047) and perceptions of susceptibility (d = 0.195, p = .025), but no effect on perceptions of severity (d = -0.036, p = .828). Interventions showed no effect on intention to vaccinate (d = 0.138, p = .195) and no effect on vaccination behaviour (d = 0.043, p = .826). Interventions typically did not include many behaviour change techniques (BCTs), with the most common BCT unique to intervention conditions being 'Information about Health Consequences'. Few of the included studies attempted to, or successfully increased, efficacy appraisals.

conclusionsOverall, there is a lack of good-quality primary studies, and existing interventions are suboptimal. The inclusion of additional BCTs, including those to target efficacy appraisals, could increase intervention effectiveness. The protocol (CRD42015029365) is available from http://www.crd.york.ac.uk/PROSPERO/. Statement of contribution What is already known on this subject? Previous research indicates that an increase in risk appraisal is associated with increased uptake in health-related behaviours. Research suggests that interventions increasing risk appraisal have a greater effect on intention when elements of efficacy appraisals are simultaneously increased. What does this study add? This is the first systematic review to examine the effect of interventions on risk appraisal and vaccination uptake using only experimental studies. Limitations of the interventions themselves, and those caused by study methods and reporting, mean that the potential value of this type of review is lost. Instead, its value is in shining a light on the paucity of experimental studies in this area, and the quality of methods and reporting used. Future experimental studies should examine interventions that focus exclusively on increasing risk and efficacy appraisal compared to controls, use conditional measures of risk, and improve reporting to enable both more accurate coding of intervention content and more accurate assessments of study bias.