They do so by over-reporting and fear-mongering, as exemplified by the current Zika virus scare, but they also do the bidding of their corporate masters by under-reporting, ignoring and burying stories that might threaten their profit margins or even put them out of business altogether.
Such is the case regarding thimerosal (a vaccine additive which contains as much as 50 percent mercury) and its link to cases of autism in children. It's true that most people have at least heard something regarding the issue, but all one ever sees in the mainstream news are denials that there is a link, and reassurances by federal agencies such as the Centers for Disease Control and Prevention (CDC) that the mercury added to vaccines poses no risk to children.
The official CDC stance is: "There is no evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site."
What if that statement turned out to be a complete falsehood, and the CDC knew all along that there was a clearly demonstrated connection between exposure to mercury in vaccines and a heightened risk of autism?
You would probably expect that story to generate some headlines in the news, right?
The truth is that it has been undeniably proven, through a whistleblower's successful efforts to obtain the relevant documents through the Freedom of Information Act (FOIA), that the CDC indeed did know – all along – that thimerosal in vaccines does indeed cause autism in children.
Dr. Brian Hooker, a PhD scientist whose son developed autism after being injected with a thimerosal-laced vaccine, took it upon himself to force the CDC to reveal what it knew about the dangers of thimerosal.