I've read the same thing as netmiff said. By killing off all the bacteria and germs with cleaners, hand sanitizers, etc., we could be killing off things that we need to stay healthy. Similar to the problems caused by the overuse of antibiotics. Then, super germs will develop and we'll have to find super cleaners and antibiotics to kill them. Then super super germs will develop. It is a vicious cycle. Wash your hands regularly, brush your teeth, bathe, and take good care of your body. Anything that gets through these defenses would have made it through anyway.