What Do Popular YouTube™ Videos Say about Vaccines?

Previous studies have identified YouTube™.com as a major host of medical and health information with the power to sway consumer opinion about controversial health topics such as vaccine safety. This study examines YouTube™ videos dealing with vaccines. It describes the source, date uploaded, view count, length, consumer ratings, proportion that are anti-vaccine and pro-vaccine, content covered, use of scientific evidence, and use of celebrities.

All videos with over 25,000 views as of December 21 2015 were selected for examination; the final sample was n = 87 videos. Analysis revealed:

• Top topics were autism causality (47.1% of videos), risks not being fully disclosed and/or understood (42.5%), signs or symptoms of adverse reactions to vaccines (40.2%), and use of thimerosol or mercury adjuvants in vaccines (36.8%).
• Over one-third of videos (36.8%) presented no scientific evidence to support their stance. Anti-vaccine animal studies were cited in 46.0% of the videos, and pro-vaccine human studies were cited in 17.2%.
• The median number of thumbs up ratings was 480, and the median number of thumbs down ratings was 54.
• The 3 most common sources of these YouTube™ videos were consumers (27.6%), TV- or internet-based news (26.4%), and individual health professionals (25.3%). Only 5.6% of the videos came from government professionals, and only one video (2.2%) originated on commercial television. The single commercial television video accounted for almost one-third (31.3%) of total views. Consumer-generated videos accounted for only 10.3% of views. Videos from a non-profit organisation accounted for 20.6% of views, and news clips accounted for 16.6% of views.
• The majority of videos (65.5%) were anti-vaccine; 25.3% were pro-vaccine and 9.2% maintained a neutral stance. Percent of views associated with pro-vaccine and anti-vaccine videos were nearly equal.
• Only 13.8% of videos featured a celebrity.

The researchers note that there is a preponderance of anti-vaccine views (67.5% versus 26.1% pro-vaccine). A notable exception is a pro-vaccine video entitled 'A message for the anti-vaccine movement' (see below), from a popular television show in the United States (US). The 4-minute and 57-second video, featuring both the monologue by the host of the show (Jimmy Kimmel) and the testimony of medical doctors, had, by far, the highest view count (6,229,835) and also had the highest number of thumbs up (33,000) and of thumbs down (4,000). The video is described here as "both edifying and entertaining".

In conclusion: "Health professionals should be aware of the widely disseminated vaccination information available on the Internet and should appreciate its possible effect on the public. It would be advisable for public health agencies to produce and disseminate accurate and appealing messages about vaccination through YouTube™ and other widely viewed media."