:::info This paper is available on arxiv under CC 4.0 license.

Authors:

(1) Pietro Ghezzi, Brighton & Suss*x Medical School, Falmer, Brighton, UK;

(2) Peter G Bannister, Brighton & Suss*x Medical School, Falmer, Brighton, UK;

(3) Gonzalo Casino, Communication Department, Pompeu Fabra University, Barcelona, Spain and Iberoamerican Cochrane Center, Barcelona, Spain;

(4) Alessia Catalani, Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, PU, Italy;

(5) Michel Goldman, Institute for Interdisciplinary Innovation in healthcare (I3h), Université libre de Bruxelles;

(6) Jessica Morley, Oxford Internet Institute, University of Oxford, Oxford, UK;

(7) Marie Neunez, Institute for Interdisciplinary Innovation in healthcare (I3h), Université libre de Bruxelles;

(8) Andreu Prados, Communication Department, Pompeu Fabra University, Barcelona, Spain, Iberoamerican Cochrane Center, Barcelona, Spain, Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, PU, Italy, Institute for Interdisciplinary Innovation in healthcare (I3h), Université libre de Bruxelles, Oxford Internet Institute, University of Oxford, Oxford, UK, and Blanquerna School of Health Sciences, Universitat Ramon Llull, Barcelona, Spain;

(9) Mariarosaria Taddeo, Oxford Internet Institute, University of Oxford, Oxford, UK, Blanquerna School of Health Sciences, Universitat Ramon Llull, Barcelona, Spain, and The Alan Turing Institute, London, UK;

(10) Tania Vanzolini, Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, PU, Italy;

(11) Luciano Floridi, Oxford Internet Institute, University of Oxford, Oxford, UK, Blanquerna School of Health Sciences, Universitat Ramon Llull, Barcelona, Spain, and The Alan Turing Institute, London, UK.

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Table of Links

• Abstract and Introduction
• Methods
• Web search and content analysis
• Results
• Discussion
• Conclusion and References
• Table 1. Example of classification of webpages
• Table 2. Percentage of vaccine-negative webpages in different SERPs

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Results

Figure 1 shows the ranking of positive (green), neutral (yellow), and negative (red) websites returned by the different search engines in English, French, Italian and Spanish.

\ A comparison of the percentage of vaccine-negative webpages in different SERPs (Table 2) shows that Google is consistently returning less misinformation, although some of its local version show more vaccine-negative webpages than the English-US version (Google.com). Other search engines return some vaccine-negative webpages with some, like Mojeek in English-UK and Arianna and Virgilio in Italian are the most likely to rank higher webpages with misinformation. In English, the frequency of vaccine-negative webpages in Yahoo, Bing and Mojeek was significantly higher than in Google.com. In Italian, all SERPs had a significantly higher proportion of vaccine-negative webpages compared with Google.com.

\ In French, all search engines returned a significantly higher number of vaccine-negative webpages than Google.com or the local version Google.fr. There were no significant differences for search engines in Spanish.

\ The SERPs of all search engines providers contained a higher proportion of vaccine-negative results than those obtained from Google.com. Even the localized versions of Google (Google.co.uk, Google.it and Google.es) returned more negative pages than the US/international English Google.com. The two Italian-only search engines (Virgilio and Arianna) returned the highest number of negative pages in Italian.

\ In several instances, the same webpages were returned by different search engines, with large overlaps between these results as shown in Figure 2.