I don't like shaking hands in general because you'll always run into guys who think it's a competition and squeeze your hand hard enough to make a diamond. So when I go to shake, I just give them a few fingers, not the whole hand. I'm basically recognizing their dominance as the alpha. That seems to work better.
But on the general concept of shaking in regards to contagion, I've never worried about that. While I don't think you should deliberately try to infect yourself with pathogens, the fact remains that if you have a robust immune system, it's not something you need to worry about.
The one exception to that which I've found is warts. A few months ago and for the very first time in my life I got a small wart on the ring finger of my right hand. I was very upset.
And those suckers aren't that easy to get rid of I've found. I've been wearing a small patch with salicylic acid (I think) for weeks now and there is still a tiny little bump where the wart used to be. But I can't stop now since it will just grow back. So I probably have a few more weeks to go.