MadeAliyah, I think Yserbius is making a point that flu transmission is symptomatic (there is also existing immunity – thus adults being more protected). So, flu transmission wuold go dramatically down were the people/children stay home when visibly sick. Maybe you are right and after this pandemic, there will be more understanding or even shaming of people who contribute to flu pandemics. Or maybe more chumros in natilas yadaim …
We might be in general exposed to a lot of stuff that we are not paying attention to. When my older kids went to school first time for K (in a small school), being solely at home previously, the whole family was continuously sick with multiple symptoms for 6 months from getting the whole load in one shot.