Communicating on Vaccine Benefit-Risk Ratios: A Discrete-Choice Experiment among Health Care Professionals and the General Population in France

Background: We explored preferences around the benefit-risk ratio (BRR) of vaccination among the general adult population and health care sector workers (HCSWs). We estimated preference weights and expected vaccine uptake for different BRR levels for a vaccine recommended during an infectious disease emergence. In addition, we explored how far qualitative information about disease severity, epidemiological context, and indirect protection interacts with these preferences.

Methodology: This was a cross-sectional study, using a self-administered online questionnaire containing a single-profile discrete choice experiment among HCSWs and the general population in France (quasi-representative sample). The questionnaire was available from January 12 to April 27, 2023, for HCSWs and from April 17 to May 3, 2023, for the general population. BRR is represented as the number of vaccine-prevented disease events for 1 event related to a vaccine side effect. Results are reported in 4 groups: general population sample, non-HCSWs, non-university-degree HCSWs, and university-degree HCSWs.

Results: Among the 1,869 participants, 1,038 (55.5%) varied their vaccine decision among the different vaccine scenarios. Hypothetical vaccine acceptance among university-degree HCSWs increased when the vaccination BRR was 100:1, while non-university-degree HCSWs and non-HCSWs were more sensitive to qualitative information about the vaccine BRR than quantitative indicators. Among participants in the general population sample with varied decisions, expected acceptance increased by 40% sample if disease risk was high. Among serial vaccine nondemanders, high disease risk decreased their certitude to refuse hypothetical vaccination.

Conclusion: Our results suggest that only university-degree HCSWs are sensitive to the notion of BRR, but not the general public. Given that previous research found speaking about BRR might reduce vaccine acceptance, this notion should be avoided in vaccine promotion.

Highlights: The notion of benefit-risk ratio (BRR) of vaccination appears to be taken into account in vaccine decisions by university-degree HCSWs, but not by the general public. Mentioning a favorable BRR could imply that the vaccine is not safe and reduce vaccine motivation.Mentioning qualitative attributes of BRR surrounding disease frequency and severity, and indirect protection effects, strongly affected theoretical vaccine decisions in all participants, irrespective of professional categories.Expected vaccine acceptance increased by 40% among the general population sample if disease risk was presented as high, and expected vaccine coverage exceeded 50% in scenarios with high disease risk.Among those refusing vaccination in all vaccine scenarios, only a high risk of developing the disease decreased their certitude to refuse vaccination. This further underlines the importance of disease risk perception on vaccine decision making, including among persons who a priori are unlikely to accept vaccination.