1st choice: Calcifediol preferred: 0.5 mg by mouth day 1, then 0.2 mg by mouth day 2 and weekly thereafter
2nd choice: Cholecalciferol: 20,000–60,000 IU single dose by mouth then 20,000 IU weekly
Calcifediol (also called calcidiol) is a fast-acting vitamin D. Regular D3 has to be converted to Calcifediol in the liver before it is used, and this can take 7 days.
It is sad that great protocols are not widespread. Doctors here are still using ventilators and sending people home until they need them.