How has the flu virus infected the Web? 2010 influenza and vaccine information available on the internet

Background: The 2009–10 influenza pandemic was a major public health concern. Vaccination was recommended
by the health authorities, but compliance was not optimal and perception of the presumed associated risks was
high among the public. The Internet is increasingly being used as a source of health information and advice. The
aim of the study was to investigate the characteristics of websites providing information about flu vaccine and the
quality of the information provided.
Methods: Website selection was performed in autumn 2010 by entering eight keywords in two of the most
commonly used search engines (Google.com and Yahoo.com). The first three result pages were analysed for each
search, giving a total of 480 occurrences. Page rank was evaluated to assess visibility. Websites based on Web 2.0
philosophy, websites merely displaying popular news/articles and single files were excluded from the subsequent
analysis. We analysed the selected websites (using WHO criteria) as well as the information provided, using a
codebook for pro/neutral websites and a qualitative approach for the adverse ones.
Results: Of the 89 websites selected, 54 dealt with seasonal vaccination, three with anti-H1N1 vaccination and 32 with
both. Rank analysis showed that only classic websites (ones not falling in any other category) and one social network
were provided on the first pages by Yahoo; 21 classic websites, six displaying popular news/articles and one blog by
Google. Analysis of the selected websites revealed that the majority of them (88.8%) had a positive/neutral attitude to
flu vaccination. Pro/neutral websites distinguished themselves from the adverse ones by some revealing features like
greater transparency, credibility and privacy protection.
Conclusions: We found that the majority of the websites providing information on flu vaccination were pro/neutral
and gave sufficient information. We suggest that antivaccinationist information may have been spread by a different
route, such as via Web 2.0 tools, which may be more prone to the dissemination of “viral” information. The page
ranking analysis revealed the crucial role of search engines regarding access to information on the Internet.