title: Assessment of vaccination-related information for consumers available on Facebook.
abstract: OBJECTIVE
  To assess the magnitude, interest, purpose and validity of vaccination-related information on Facebook and to determine whether information varies by site viewpoint.
  
  
  METHODS
  The 10 largest vaccination-focused Facebook pages, groups and places in each category were identified and classified by viewpoint (i.e. anti-, pro-, neutral) and purpose. Number of members, posts per week, likes, comments and shares per post were recorded. Posts were assessed for concordance with CDC and FDA recommendations.
  
  
  RESULTS
  Of 30 sites, 43% (n = 13) were anti-vaccination, 7% (n = 2) neutral and 50% (n = 15) pro-vaccination. Most sites were most popular with American users. Median members were similar between anti-vaccination (2703 members, range 337-33 631 members) and pro-vaccination sites (2142 members, range 456-61,565 members, P = 0.262); however, anti-vaccination sites accumulated more posts per week by authors (median 15 vs. 3, P = 0.031) and members (median 33 vs. 1, P < 0.001). Pro-vaccination sites more commonly had commercial purpose (53% [n = 8] vs. 8% [n = 1], P = 0.02). Anti-vaccination sites more commonly gave medical advice (54% [n = 7] vs. 0%, P = 0.004). Overall, 48% (n = 22) of author posts were concordant with regulatory recommendations; concordance was more common on pro-vaccination sites (78% [n = 21] vs. 5% [n = 1], P = 0.0002).
  
  
  CONCLUSIONS
  Vaccination-related information is prevalent on Facebook regardless of viewpoint; however, anti-vaccination information generates more interest. Anti-vaccination sites were likely to provide medical advice and disagree with regulatory bodies.
authors.affiliation: PGY2 Pharmacy Resident, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Buchanan
authors.forename: Robert D
authors.initials: RD
authors.lastname: Beckett
mesh_terms: D054626:Consumer Health Information / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D057226:Information Seeking Behavior; D020407:Internet; D061108:Social Media / Q000706:statistics & numerical data*; D014611:Vaccination
keywords: consumer health information; health information needs; information seeking behaviour; social media; social networking