One thing to do is to have everyone of adult size (including older teenagers) take a Vitamin D supplement of about 2000 units a day. Alternatively they could stay in the bright sunlight 20 mins a day (or more if the skin is dark) with a lot of skin exposed (legs, arms, head). The latter is perfectly fine for little kids too. No sunscreen.
There is evidence that people with enough Vitamin D in their systems don’t get the flu. You can google it for more info.
If that is correct then there might be a massive reduction of Islamic fundamentalist: Burkas
Thanks for the information. I’ll pass it along to grandkids - they enjoy the sun now...