Camps have closed for the summer due to swine flu or polio and have come back the next summer. Total infections and deaths were far fewer than covid-19,  but children were more susceptible to polio though adults would contract it too.  Some kids spent years in iron lungs, the ventilators of back in the day. A few used leg braces or wheelchairs for life.  The threat lasted for decades before vaccines were developed.  Some of us grey beards have a round polio vaccination scar, the mark o