Certainly washing hands is not the end of everything, but it cuts about 20% of the total number of transmissions, for flu at least. So it is significant, when y

Certainly washing hands is not the end of everything, but it cuts about 20% of the total number of transmissions, for flu at least. So it is significant, when you have a pandemic with a virus for which nobody has immunity. The second point is that the less you have fat on your hand skin, the shorter lived is the virus when it lands on it. That is the rational behind "wash your hands often" messages.