One of my major pet peeves (I don't have many) is the use of misinformation or irrational ideas to scare people into doing or avoiding specific actions (This is probably why I don't get along with politicians very well). One of the more recent ideas that infuriates me is notion that vaccines are harmful and should be avoided. This is especially infuriating because the original article that started this movement has not only been proven to be wrong many times but the journal that printed it has retracted the article and distanced itself from the disgraced scientist who wrote it to help "prove" a notion in a lawsuit. Despite all of this, people still refuse to vaccinate due to a misguided conspiracy theory and children die because of this choice. And not only are the children who are not vaccinated at risk but anyone around them is at risk due to them being carriers (vaccines don't protect from viruses 100% of the time but they do prevent the spread of the disease so those who aren't fully protected by the vaccine never come in contact with the virus).
Anyways, Penn and Teller recently did a piece on Vaccines and they put it far more bluntly than I ever could: Even if what was said was true about vaccines (it is not) those risks are far better than the thousands of deaths and disabled children caused by not vaccinating.
You can find the entire show here and here (warning, some harsh language and random nudity at the very end)