  The fact that internet companies may record our personal data and track our
online behavior for commercial or political purpose has emphasized aspects
related to online privacy. This has also led to the development of search
engines that promise no tracking and privacy. Search engines also have a major
role in spreading low-quality health information such as that of anti-vaccine
websites. This study investigates the relationship between search engines'
approach to privacy and the scientific quality of the information they return.
We analyzed the first 30 webpages returned searching 'vaccines autism' in
English, Spanish, Italian and French. The results show that alternative search
engines (Duckduckgo, Ecosia, Qwant, Swisscows and Mojeek) may return more
anti-vaccine pages (10 to 53 percent) than Google.com (zero). Some localized
versions of Google, however, returned more anti-vaccine webpages (up to 10
percent) than Google.com. Our study suggests that designing a search engine
that is privacy savvy and avoids issues with filter bubbles that can result
from user tracking is necessary but insufficient; instead, mechanisms should be
developed to test search engines from the perspective of information quality
(particularly for health-related webpages), before they can be deemed
trustworthy providers of public health information.
