title: What do popular YouTubeTMvideos say about vaccines?
abstract: The unregulated social network YouTubeTMhas become an increasingly popular source of information on health topics such as vaccine safety. With a reach of over one billion users per month, the potential for misinformation is significant.
  
  
  
  Using the keywords 'vaccine safety' and 'vaccines and children', 87 of the most widely viewed YouTubeTMvideos were identified and analyzed for content, author status and view count.
  
  
  
  The range of view counts was 25 532 to 6 229 835, with a median of 62 075 views per video. Most videos (n = 74, 85.1%) were devoted exclusively to the topic of vaccination. The three most common sources of these YouTubeTMvideos were consumers (27.6%), TV-based or Internet-based news (26.4%) and individual health professionals (25.3%). Top topics covered were autism causality (47.1% of videos), undisclosed or poorly understood risks (42.5%), adverse reactions (40.2%) and thimerosol or mercury in vaccines (36.8%). The majority of videos (65.5%) discouraged the use of vaccines.
  
  
  
  Health professionals should be aware of the widely disseminated vaccination information available on the Internet and should appreciate its possible effect on the public.
authors.affiliation: Department of Public Health, William Paterson University, Wayne, NJ, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Basch
authors.affiliation: Health and Behavior Studies, Teachers College, Columbia University, New York, NY, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zybert
authors.affiliation: Department of Public Health, William Paterson University, Wayne, NJ, USA.
authors.forename: R
authors.initials: R
authors.lastname: Reeves
authors.affiliation: Health and Behavior Studies, Teachers College, Columbia University, New York, NY, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Basch
mesh_terms: D002648:Child; D003142:Communication; D003430:Cross-Sectional Studies; D019317:Evidence-Based Medicine / Q000592:standards; D006266:Health Education / Q000379:methods / Q000592:standards; D006801:Humans; D033181:Information Dissemination; D061108:Social Media / Q000592:standards / Q000706:statistics & numerical data*; D014611:Vaccination / Q000009:adverse effects; D000072758:Vaccination Refusal / Q000706:statistics & numerical data; D014612:Vaccines; D014741:Video Recording
chemical_list: D014612:Vaccines
keywords: child public health; immunization