UC Davis

Online social networks have the potential to influence individuals’ health, from providing information to influencing beliefs and behaviors. They provide key differences from offline social networks, including the ability to maintain anonymity and make new connections in online support groups. It is important to develop an understanding on how online networks can be leveraged to influence health outcomes. The promotion of HIV pre-exposure prophylaxis (PrEP), which refers to taking a daily oral medicine to reduce the risk of contracting HIV, may benefit from the potential effects and mechanisms that online networks possess. This dissertation consists of two comprehensive studies that examine the role of online networks for PrEP adoption. The first study involves a quantitative content analysis using a theoretically grounded framework to examine Twitter discussions surrounding PrEP from April 2019 to April 2020, six months before and after the approval of Descovy for PrEP. The contents, sources, and sentiments and emotions expressed in tweets were examined. Through the lens of the Theory of Planned Behavior (TPB), I extract the beliefs and barriers that are related to PrEP adoption behaviors. Results indicate, after the approval of Descovy, there was a significant decrease in tweets on barriers to PrEP, specifically relating to access. In addition, there was a significant increase in positive emotions expressed by users. However, the lack of tweets that involve attitudes, norms, and behavioral control prompt a need for future work in addressing these beliefs when promoting the uptake of PrEP. Implications on developing message strategies are discussed. The second study involves an online, one-week network intervention employed through a mobile app. This field experiment randomly assigned participants into a social support condition or information-only control, where participants are placed into homophilous, small online groups. Both conditions involved an information component consisting of messages, guided by TPB, aimed at addressing knowledge, beliefs, and barriers related to PrEP adoption. Social support was operationalized through an online chatting tool where participants can discuss topics surrounding PrEP. Results indicate that the intervention overall increased participants’ familiarity with PrEP, as well as their knowledge of how much consistent use of PrEP reduces the likelihood of HIV acquisition. Further, the intervention increased participants’ intentions and attitudes toward taking PrEP, such that users had higher intentions and more positive views toward starting PrEP after the mobile app intervention compared to their baseline intentions and attitudes. Overall, these studies illuminate the potential capabilities of online networks to promote positive health behaviors. Assessing online discourse surrounding a health topic may be particularly useful for pinpointing the relevant beliefs and barriers associated with a health behavior. Through both disseminating theoretically driven, tailored messaging and harnessing the social connections within the networks, leveraging online networks to develop interventions can provide researchers and practitioners with the tools to promote healthy behaviors. Theoretical contributions relating to the effects and mechanisms of online networks on health behaviors, as well as the practical implications, are discussed.