The important factors for Vitamin D are that it's cheap to manufacture and has well known (low) risks. We have reasons to believe that it might help fight Covid, especially in deficient individuals, even if we do not have controlled studies.
Making it freely available and recommended for anyone who doesn't obviously get enough already is a reasonable strategy. It might not work - the correlation may not be causal. But it might be worth it anyway, because the downsides are minimal.
You could make roughly the same argument for wearing masks.
Making it freely available and recommended for anyone who doesn't obviously get enough already is a reasonable strategy. It might not work - the correlation may not be causal. But it might be worth it anyway, because the downsides are minimal.
You could make roughly the same argument for wearing masks.