Levels and factors derived from the Health Action Process Approach of behavioral intentions to take up COVID-19 vaccination: A random population-based study

•Very low prevalence of intention of free COVID-19 vaccination (11% if 50% effectiveness) was reported.•A low proportion of participants (13%) would like to take up COVID-19 vaccination as soon as it becomes available.•Positive/negative outcome expectancies were associated with intention of COVID-19 vaccination.•In general, the associations involving risk perception/self-efficacy were non-significant.•Health promotion that modifies positive and negative outcomes is greatly warranted. COVID-19 vaccination needs a high population coverage to achieve herd immunity. We investigated prevalence of three scenarios of intention of free COVID-19 vaccination involving: 1) 80% effectiveness and rare and mild side effects (Scenario 1), 2) 50% effectiveness and rare and mild side effect RMSE (Scenario 2), and 3) immediate vaccination (Scenario 3), and their associated factors derived from the pre-intentional motivational phase of the Health Action Process Approach (HAPA). A random population-based telephone survey interviewed 450 Chinese adults in the general population (September 16–30, 2020). The four HAPA constructs included a) risk perception scale, b) overall scale/four subscales of positive outcome expectancy of COVID-19 vaccination, c) overall scale/three subscales of negative outcome expectancy of COVID-19 vaccination, and d) the overall scale/two subscales of self-efficacy of COVID-19 vaccination. The prevalence of intention of COVID-19 vaccination under Scenarios 1 to 3 was 38.0%, 11.1%, and 13.1%, respectively. Logistic regression analyses adjusted for background factors showed that 1) the associations between risk perception and the three scenarios of intention were non-significant; 2) the overall scale/four subscales of positive outcome expectancy were in general positively associated with two scenarios of intention (80% effectiveness and immediate vaccination); 3) the overall scale/three subscales of negative outcome expectancy were in general negatively associated with all three scenarios of intention; 4) the overall scale/two subscales of self-efficacy were only positively associated with the intention that involved 80% effectiveness. When all the four overall scales were entered into an adjusted model, positive and negative outcome expectancy, but not risk perception and self-efficacy, were independently associated with the three scenarios. In this study population, the prevalence of intention of COVID-19 vaccination was very low and might not result i