They were the original superbugs - mumps, measles, polio and rubella. Thanks to modern immunisation, we don't see these diseases much any more. So most of us have no first-hand knowledge of how dangerous they can be. Maybe that's why so many parents are questioning whether vaccination is the right choice for their children. And once they tap into the bottomless pit of misinformation, swirling around the internet, fears are fuelled, minds are made up and they may just say no to the needle. On Sunday night, you'll meet some of the self-appointed experts behind the anti-vaccine campaign and some grieving parents who couldn't disagree with them more.