People should stop shaking hands from October until April. That's preposterous, you might say, but some people seriously suggest it. That's the sneezey season. People customarily grab their hanky or a tissue to cover their faces, if they're fast enough, but as often as not wind up sneezing into their hands.
The medics tells us that cold and flu germs don't do well in an airborne environment—they don't spread so much by sneezes as people think. They spread mostly by touch. The germiest thing most people ever touch is a door knob in public buildings. Or by shaking hands with an already infected victim, who, as often as not, has recently sneezed into that hand. It may be inconvenient or impossible for them to wash that hand, even if the thought occurs to them.