Most recently, the FDA has been attempting to ban every effective treatment for ncov, because it makes their graft look bad by comparison.
They can't stop vitamin D. Sunlight in a bottle.
I can't explain this except thaumaturgically. Government is literally vampires and burn if they attempt to touch truly sacred things.
As long as it occurs to you, you can just not send your kids to school. As a percentage it's super low, but in absolute numbers lots of folk do it, and it works out fine.
See also: the Amish exist.
Twitter is inherently profane, so they can't (really) think of vitamin D either. This is the mechanism in this one particular. Since twitter won't defend it, the government won't attack it, and you can continue being immune to all viruses (not just coronaviruses) for the price of roughly $30 a month...assuming you never go outside and get the free stuff.
Voters are thaumaturgically government, so regularly forget e.g. the Amish exist. The sacred impinges on memory of the Amish, and the memories burn themselves out of their brain.