Trend of influenza vaccine Facebook posts in last 4 years: a content analysis

Background: Decreasing immunization rates may be partly due to antivaccine campaigns and other sources of misinformation available on social media, particularly on Facebook. Given the potential impact of this medium for communicating vaccine-related information, it is important to analyze the trend of information available on Facebook. Methods: We searched Facebook on August 15, 2018 to obtain posts containing relevant health information on influenza vaccine in years 2015-2018. We collected information regarding nature of the post (eg, pro-, antivaccine, and informational), number of shares and likes received, and ease of reading for each post. We evaluated these characteristics by year and type of post in our exploratory analyses. Results: The proportion of pro-vaccine posts has increased compared to antivaccine and informational posts since 2016. There was no correlation between ease of reading and popularity of posts. Although the language of antivaccine posts was complex, they were shared and liked more than pro-vaccine posts. The pro-vaccine personal post by a nurse was the most popular in our study (shared over 46,000 times) in 2018. Conclusions: Though the number of pro-vaccine posts increased, antivaccine posts remained more popular. The government agency may use an emotive personal family-oriented message to promote vaccination.