Vitamin D was a top COVID-19 treatment at 4 hospital groups
| Source | approximate # of patients |
| Columbia University Irving Medical Center | ~ 6,500 |
| Hospital del Mar | ~ 644 |
| https://www.iqvia.com/ | ~ 66,185 |
| VA data model | ~ 10,403 |
| Total | ~ 83,000 patients |
Data from: Treatments for 303,000 COVID-19 patients: vitamin D is both popular and over-the-counter – May 2021
See also: Clinical trials are proving that Vitamin D fights COVID-19 in hospitals