If we act on the data showing that it is highly probable that vitamin D can save lives, we could fix this pandemic in a month, for perhaps $2 per person. There would be no significant adverse effects. If we wait for “evidence” that vitamin D mitigates the impact of COVID-19, thousands more will die. If we could arrange to give everyone vitamin D, and it failed to protect them, so what? The risk of not acting is much greater than the risk of acting. Dosage is important and generally misunderstood.