Thank you all for so much feedback

I have decided to continue to ask people to wash hands, if I am here on MDC asking this very question, then it likely signals I am not ready to stop requesting people to wash hands.
At this age (11 weeks) his immunoglobulin development, the main defense of his immune system, has just begun to make it's own antibodies. As much as I believe in my breastmilk's ability to transfer antibodies, I would feel a lot more comfortable waiting for his own immune system to develop the immunoglobulins so that it can fight viruses and bacteria. Right now it's really just begun to develeop those. I've found conflicting info pertaining to when IgG, IgM and IgA are fully functional, I see anywhere from 6 months to 2 years, so that bugs me a bit on which side to err.
The more I think about it, and read the nature of the way it develops, I'd better continue to ask people to wash, even if it's for my own peace of mind.

Thank you all so much for your replies!