A few sources to start with...
Articles, Consumer Data Reports, Digital Trends Reports, etc. within Databases...
Additional databases to explore...
These are not the only resources that can provide relevant sources for your work. Search the other pages within the Public Health guide for others. Also consider searching the "Books & Media" tab on the library homepage for e-book/print books about "social marketing" AND health, "social media" AND health, media AND "public health", "target marketing", "audience research", etc.
Always be a critical evaluator of the authority, bias, credibility, currency, purpose, references/citations and reliability of each source before use.