How can you tell whether information you find on the web is accurate? The following criteria can help you with evaluating web resources.
Accuracy: The domain (i.e. .com) can tell you a lot about a website. Sites can be .com (commercial), .edu (academic institutions), .gov (governmental), .mil (military), or .org (organization - usually non-commercial). Of these, .edu and .gov sites are the most trustworthy.
Objectivity: Is the site subjective (opinion-based) or objective (fact-based)?
Timeliness: Hunt around for a "last updated" statement. If it's been more than a year or two since the last update, it can be a clue that the site is not maintained very well.
Authority: Can you find out who the author of the content is? If so, is s/he an expert on the subject? Does the author leave contact information?
Blog from the CDC:
"Sharing our stories on preparing for and responding to public health events"