Very few studies have examined information sentiment and explored other factors that contribute to health information dissemination and sharing. In particular, there is a lack of studies that performed these combined analyses in the modern social network environment during the disease outbreaks, such as with zika, ebola, SARS, or COVID-19. This study aimed to fill the gap in the literature by investigating what drives social media users to widely disseminate health-related information during a pandemic. Diffusion of innovation theory and theory of planned behavior were the basis of the theoretical approach utilized to answer the research questions. The two theories identified antecedents of sharing online health information. Data was collected through an online survey distributed to students in a higher education institution in the United States of America. The study revealed the extent of the relationships between the four major factors derived from the previous literature—attitudes toward sharing, beliefs toward source, peer influence, and information sentiment—and the behavioral intention to share information. The results would support the information science literature by offering and testing a new model that identifies the factors that affect users' intentions to share health information in the social network environment. This study will further the understanding and application of health information behavior research.