Testing Theory-Enhanced Messaging to Promote COVID-19 Vaccination: Results from a Randomized Controlled Trial.

Uptake of the COVID-19 vaccine has been low in the US (~ 22% among adults in 2023 - 24) despite ongoing public health recommendations. This has been linked to many factors including pandemic fatigue, reduced risk perception, dis/misinformation, and recently, symptoms of depression and anxiety. Novel communication and messaging strategies are one potential approach to promote vaccine uptake. This randomized control trial tests two communication-based approaches compared to standard public health messaging on vaccine uptake in a cohort of adult US residents. We completed a 3-arm, parallel-group, assessor-blinded stratified-randomized trial between April-15-2024 and May-2-2024. Eligible individuals were ≥ 18 years old who: 1)had received at least one dose of the COVID-19 vaccine, but, 2)had not received COVID-19 vaccine doses since September-11-2023, and 3)had not been infected with SARS-CoV-2 in the past three months. We purposively sampled eligible individuals with and without symptoms of anxiety and depression. Participants were randomly allocated to: 1) attitudinal inoculation intervention; 2) CBT-kernels intervention; or 3) standard public health messaging intervention. At four-week follow up, these groups showed no meaningful differences in uptake (CBT- kernels:1.6% [95%CI:0.4-2.8]; Inoculation:0.9% [95%CI:0.0-1.8]; and Standard:1.3% [95%CI:0.3-2.4]) or level of vaccine willingness. Successful efforts to increase uptake of the COVID-19 vaccine via theory-enhanced messaging remain elusive.