KEYWORDS:
anti-vaccination, anti-immunization, vaccination, immunization, survey, internet, web

BACKGROUND:
Over the last decade, a persistent and vocal anti-vaccination movement, increasingly visible on the Internet, has had a prominent influence in questioning the safety and efficacy of widespread vaccination of the public.

OBJECTIVE(S):
The purpose of this study was to evaluate the content of the more prominent anti-vaccination websites.

METHOD(S):
A sampling of ten internet search engines was used to search the internet using the keywords above. Anti-vaccination sites were systematically selected that were specific for opposition to childhood immunizations. An initial 772 links were sorted, from which twelve sites met our inclusion/exclusion criteria, with an additional ten sites chosen using "backlink" analysis, for a total of 22 sites. Each site was analyzed for the presence of any of eleven anti-vaccination "claims", as well as for ten site characteristics, such as whether or not there were pictures of children allegedly injured by vaccinations.

RESULT(S):
Eight of the eleven claims were presented on over 66% of the 22 sites. The most common claims were that vaccines cause idiopathic illness (100%), adverse vaccine events are under-reported (95%), vaccines erode immunity (95%), and vaccine policy is driven by profit (91%).

CONCLUSIONS(S):
Studied anti-vaccination sites were heterogeneous in their content and motivations, with a range from scientific to highly unscientific. Most made strong emotional appeals, with striking visual images. Physicians need to be aware of the subtle and unscientific arguments used by anti-vaccination groups and how to counter them. Attempts to counter anti-vaccination arguments must be tempered by a need to maintain and nurture the doctor-patient relationship.

LEARNING OBJECTIVES:
1. To acquaint healthcare providers with anti-vaccination arguments present on the internet, and how they use psychologically persuasive techniques.
2. To stimulate discussion and thought on ways of tailoring communication about vaccinations with parents to help reduce misinformation and inappropriate concerns about vaccine safety.