Excluding numeric side-effect information produces lower vaccine intentions

• Published in: Vaccine 2022-07, Vol.40 (31), p.4262-4269
• Main Authors: Shoots-Reinhard, Brittany, Lawrence, Eliza R., Schulkin, Jay, Peters, Ellen
• Format: Article
• Language: English
• Subjects: Coronaviruses; COVID-19 vaccines; Health communication; Immunization; Infectious diseases; Labels; Numeracy; Political ideology; Risk; Side effects; Vaccination; Vaccine hesitancy; Vaccines
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2022.06.001

•Provide percentages of people with side effects to increase vaccine intentions.•People overwhelmingly overestimated side-effect likelihood without percentages.•Percentages and verbal labels (“rare”) increased intentions for vaccine-hesitant.•Evidence-based formats for vaccine information may increase uptake. Encouraging vaccine uptake is important to reducing the impact of infectious disease. However, negative attitudes and vaccine hesitancy, due in part to worry about side effects, are obstacles to achieving high vaccination rates. Provided vaccine information sheets typically include a list of side effects without numeric information about their likelihoods, but providing such numbers may yield benefits. We investigated the effect of providing numeric information about side-effect likelihood (e.g., “1%”) and verbal labels (e.g., “uncommon”) on intentions to get a hypothetical vaccine, reasons for the vaccination decision, and risk overestimation. In a diverse, online, convenience sample (N = 595), providing numeric information increased vaccine intentions—70% of those who received numeric information were predicted to be moderately or extremely likely to vaccinate compared to only 54% of those who did not receive numeric information (p