That's placebo effect for you. Good placebo effect happens a lot of the time when people get well because of positively induced thinking. But bad placebo effect happens when people believer their doctor when he tells them that they are sick, even when they don't have any systems. Innocent government leaders believe the WHO who tells them that their people are sick, even when there aren't any (many) symptoms among the people. Of course, the payoff helps them believe. --- I went to the eye doctor for a prescription upgrade, because I could tell I needed it. But I stay away from doctors. I have enough people telling me negative things in my life without them.