@ihatediabetes I agree that we cannot protect ourselves completely without completely being isolated, something I cannot quite manage. "I don't know if just a drop of virus is enough to kill." Not likely unless someone is severely immunocompromised - it seems current research is beginning to show total viral load is a factor in getting ill, that is the more exposure, the more likely illness will result. This is what they believe is causing illness in so many hospital workers and first responders - LOTS of exposure over a short amount of time. And each level of protection helps lower the amount of exposure - that's why distancing, facemasks, hand washing and good sanitation work for moderate exposure. And why additional protective equipment - respirators, gowns, face shields or goggles, hair covers, etc - are so important for those with prolonged exposure.
Gradually building up immunity is NOT likely - in general this is not how viruses work. You must actually be infected with a virus for the antibodies to form, and for those with risk factors, what we are trying to avoid at this time. More likely, as widespread immunity develops in the public, there will be fewer infected people around, so less virus being spread in general. Most places are far from reaching that condition, so we have to be cautious until a vaccine is widely available.
Sue