By not having kids.

Joking, but although we are well prepared for isolation (work mostly from home, live in the countryside in one of the remotest countries in the world, have off-grid solar and 3 rainwater tanks and could probably forage enough to live for a long time from fishing and gathering), all of that is undone by having a school aged kid.

That means unavoidable contact with a wide group of other kids, from a variety of different home situations, several of whom may have runny noses etc. at any point in time.