I would like to mention that last year we also carried out a study of the information in Wikipedia about vaccines, that we presented in the European Family Medicine Conference (WONCA, Málaga, October 2010). In that study we found out that the articles in Wikipedia about vaccines were quite good but at the same time, there was a lack of information about the authors' profile of the articles (in very few cases was the author a health professional) and there were no clues to determine the country or scenario of the immunization schedules of vaccines recommended. This last point is a very important matter because each country has different schedules (there are countries such as Spain with several schedules depending on the region where the vaccine has to be applied) and therefore the recommendations may change a lot depending on where we are.
Using Wikipedia as a source of Health Information
I think that we need more studies to determine the real usefulness and applications of Wikipedia as a source of health information, for instance thinking of educational and Public Health purposes. Finally, it is very interesting to know that there are several health initiatives to promote the improvement of the medical information in Wikipedia such as Wikiproject Medicine.