Antivaccination activists on the world wide web.

AIMS To determine the likelihood of finding an antivaccination site on the world wide web and to characterise their explicit claims and rhetorical appeals. METHODS Using "vaccination" and "immunisation", examining the first 10 sites displayed on seven leading search engines. Detailed examination of content of 100 antivaccination sites found on Google. RESULTS 43% of websites were antivaccination (all of the first 10 on Google). Main rhetorical appeals involve themes of the scientific veracity of antivaccination argument; rapport with parents seeking to protect their children from harm; and alleged collusion between doctors, the pharmaceutical industry, and government to deny vaccine harm. CONCLUSIONS There is a high probability that parents will encounter elaborate antivaccination material on the world wide web. Factual refutational strategies alone are unlikely to counter the highly rhetorical appeals that shape these sites.