This study uses longitudinal methods to assess regional associations between social media posts about vaccines and attitudes and actual vaccination against influenza in the US. Geolocated tweets from U.S. counties (N = 115,330) were analyzed using MALLET LDA (Latent Dirichlet allocation) topic modeling techniques to correlate with prospective individual survey data (N = 3005) about vaccine attitudes, actual vaccination, and real-life discussions about vaccines with family and friends during the 2018–2019 influenza season. Ten topics were common across U.S. counties during the 2018–2019 influenza season. In the overall analyses, two of these topics (i.e., Vaccine Science Matters and Big Pharma) were associated with attitudes and behaviors. The topic concerning vaccine science in November-February was positively correlated with attitudes in February-March, r = 0.09, BF10 = 3. Moreover, among respondents who did not discuss the influenza vaccine with family and friends, the topic about vaccine fraud and children in November-February was negatively correlated with attitudes in February-March and with vaccination in February-March, and April-May (rs = −0.18 to −0.25, BF10 = 4–146). However, this was absent when participants had discussions about the influenza vaccine with family and friends.
Conclusions: Social media have demonstrated strong associations with vaccination patterns. When the associations are negative, discussions with family and friends appear to eliminate them. Programs to promote vaccination should encourage real-life conversations about vaccines.