Is Molluscum Contagiosum Exposure Contagious To Others?

I nanny for a little boy who just turned two. He has had bumps on the back of his neck ever since I started watching him (over a year ago). I just found out it was mollscum contagiousm and I'm wondering what the risk is of my children getting it as well. Like I said, they have been exposed for almost a year and have never shown any signs of developing it themselves. Now that I know what it is I try to make sure they don't touch it, but I'm sure they've come in contact with it at least once before now. Do some people have a natural resistance to getting the virus? Is there a way, other than covering the bumps or discontinuing our care of the child, to limit our exposure? Any other suggestions?