Myth-busting influenza and fear of adverse reactions in healthcare workers: two experimental studies on vaccination intentions.

BACKGROUND

Seasonal influenza causes significant global harms, and vaccinating healthcare workers (HCW) is central to protecting both staff and patients. However, HCW influenza vaccination rates remain below targets. Misconceptions, particularly concerns about adverse reactions, are frequently cited barriers, and many campaigns use myth-busting materials to counter these beliefs. This study tested whether correcting influenza myths and addressing concerns about adverse reactions leads to an increase in vaccine intentions.

METHODS

Two online experimental studies were conducted. HCW participants were of primary interest but a general population sample was included for comparison. In Experiment 1 (HCW n = 514; general population n = 401), participants viewed images debunking common influenza myths, with randomisation to materials that either included or excluded an additional image addressing adverse reactions. Experiment 2 (HCW n = 535; general population n = 1200) focused exclusively on adverse reaction messaging, with participants randomised to one of four image formats. Vaccination intention was the primary outcome.

RESULTS

In Experiment 1, myth-busting significantly increased vaccination intentions (all p < .001, all ηp2 > 0.12) in both samples. Adding an adverse reactions image produced no additional increase. In Experiment 2, no overall effects emerged for HCW, but a significant interaction (p = .011, ηp2 = 0.04) indicated that effects varied by image: one increased intentions (p = .029, dz = 0.25), two showed null effects, and one produced a marginal backfire effect (p = .052 dz = -0.21). In the general population sample, intentions increased overall (p < .001, dz = 0.15) with no interaction.

CONCLUSIONS

Vaccination intentions were reliably higher after viewing myth-busting materials than before, but control intentions were not. Myth-busting is therefore an effective approach to increasing influenza vaccination intentions. In contrast, explicitly addressing mild adverse reactions did not reliably raise intentions and, for one set of materials, marginally reduced them. Campaigns targeting HCW should therefore test adverse reaction messaging before implementation.