Partnering with Social Media Influencers to Promote Cancer Screening: A Process Evaluation and Practical Guidance for Influencer-Based Health Promotion (Preprint)

BACKGROUND Health communicators and researchers are increasingly exploring partnerships with social media influencers as a strategy to improve the reach and engagement of health messaging. However, practical guidance on how health communicators can identify, recruit, and collaborate with influencers is limited. OBJECTIVE The aim of this paper is to provide a detailed description of how to work with social media influencers to disseminate health messages and to highlight lessons learned that may help others avoid or overcome challenges associated with this communication channel. METHODS We conducted a process evaluation of an Instagram influencer campaign promoting colorectal cancer screening between March and July 2025. We reviewed publicly available guidance on collaborating with social media influencers for health promotion and summarized key recommendations. Using a paid influencer marketing platform, we identified and contacted nano- and micro-influencers (1,000–50,000 followers). Participating influencers created and posted an Instagram Reel and shared it to their Instagram Story. We documented the recruitment process, vetting criteria, negotiations, content review procedures, and engagement metrics and examined associations between influencer characteristics and engagement outcomes. RESULTS We sent 1,907 outreach emails to potential influencers; 72 expressed interest and we negotiated collaboration terms with 52 before finalizing agreements with 22 and receiving Reels from 16 (0.84%). Outreach emails that specified compensation and project details upfront were the most effective strategy (completed posts from 2.0% of outreach emails compared with 0.7% for emails that did not include compensation and 0% for emails sent only after pre-vetting influencers). Recruiting these influencers required approximately 2.5 months of outreach and a paid influencer marketing platform subscription costing $1,647. Influencer payments ranged from $200 to $500 (mean $389). The 16 influencer videos generated 89,764 total views (mean 5,610 per video) and approximately 232 visits to the campaign website. We found no significant associations between influencer payment or follower count and video views or engagement rates. CONCLUSIONS Partnering with influencers to disseminate health messages on social media can result in relatively high engagement with health messages, including among audiences who may not actively seek health information. However, implementing influencer campaigns using a commercial influencer marketing platform required substantial recruitment effort, including large volumes of outreach and lengthy negotiation timelines. In our campaign, fewer than 1% of outreach emails resulted in completed posts. Providing compensation and project expectations in the initial outreach email substantially improved recruitment success. Influencers with relatively fewer followers may generate similar reach and engagement at lower cost, but may be less experienced and require more clarifications and discussions in the negotiation process. Establishing clear expectations for timelines, deliverables, and revisions during negotiation may help prevent delays and improve content quality. The recruitment outcomes, timelines, and cost estimates reported here may help health communicators develop more realistic implementation plans and budgets when considering influencer-based health communication campaigns.