Abstract: It is important to understand how information of COVID-19 vaccine is organized among social media and how social media messages influence public vaccine hesitancy. Based on Prospect Theory and Framing Theory, this paper conducts a content analysis to analyze the organization of vaccine information in social media during the early period of COVID-19 vaccine promotion and explore the persuasion mechanism of vaccine information frames to ease vaccine hesitancy by online controlled experiment. This study found that: 1) nearly 20% of the weibo content about COVID-19 vaccine uses gain-loss frame, of which the gain frame is the majority. Individualism and collectivism values account for half respectively, and about 50% contain narrative elements; 2) the gain-loss frame and narrative elements may affect the comment intention of users; 3) the loss frame, individualism values and narrative elements in vaccine advocacy content help to alleviate one’s vaccine hesitancy, and there is an interactive effect between goal frame and justice perspective. The results revealed the mechanism of social media information on vaccination attitudes in the early stage of COVID-19 vaccination, providing enlightenment for the government and media in health promotion during the pandemic.

Key words: Health advocacy, Prospect theory, Gain-loss frame, Justice perspective, Narrative, COVID-19, Vaccine, Vaccine hesitancy