2.1. Study sample and data collection
DISEASE
A survey experiment incorporated within an online cross-sectional survey was conducted among working-age adults aged 18–64 years in Hong Kong, China between 13 September 2021 and 8 November 2021. Slightly over half of the eligible population (around 57%) were fully vaccinated (two doses) at the beginning of the survey (The roll-out speed of vaccination is as important as the eventual vaccination coverage of the population in an evolving situation of epidemics to prevent the disease spreading and reducing the number of people infected, hospitalized and dead. As vaccine uptake in Hong Kong population slowed before achieving potential herd immunity, we wish to find out whether relevant interventions can be applied to accelerate vaccination and increase the speed to achieve herd immunity. Therefore, apart from unvaccinated people, vaccinated people were also recruited to examine if the strategies could increase the roll-out speed by asking whether they would accept the vaccine earlier than they actually did. The participants were invited to take part through a participant panel with a well-stratified sample of working-age people, that were established in previous studies (