• Statistically significant improvements are seen in treatment studies for mortality, ventilation, ICU admission, hospitalization, and cases.37 studies from 34 independent teams in 16 different countries show statistically significant improvements in isolation (26 for the most serious outcome).• Random effects meta-analysis with pooled effects using the most serious outcome reported shows 74% [45‑88%] and 38% [31‑45%] improvement for early treatment and for all studies. Results are similar after restriction to 74 peer-reviewed studies: 70% [37‑85%] and 38% [31‑45%], and for the 47 mortality results: 76% [37‑91%] and 37% [25‑47%].• Acute treatment (early 74% [45‑88%], late 49% [32‑61%]) shows greater efficacy than chronic prophylaxis (31% [22‑39%]), suggesting that long-term supplementation may not be ideal.• Late stage treatment with calcifediol/calcitriol shows greater improvement compared to cholecalciferol: 73% [57‑83%] vs. 41% [21‑55%].• Sufficiency studies show a strong association between vitamin D sufficiency and outcomes. Meta analysis of the 126 studies using the most serious outcome reported shows 55% [50‑60%] improvement.• While many treatments have some level of efficacy, they do not replace vaccines and other measures to avoid infection. Only 13% of vitamin D treatment studies show zero events in the treatment arm.• No treatment, vaccine, or intervention is 100% available and effective for all variants. All practical, effective, and safe means should be used. Denying the efficacy of treatments increases mortality, morbidity, collateral damage, and endemic risk.• All data to reproduce this paper and the sources are in the appendix.

	Improvement	Studies	Authors	Patients
Treatment RCTs	38% [10‑57%]	18	216	6,688
Treatment studies	38% [31‑45%]	82	848	114,052
Cholecalciferol treatment	37% [28‑44%]	72	726	105,575
Calcifediol/calcitriol treatment	52% [26‑69%]	10	122	8,477
Treatment mortality	37% [25‑47%]	47	464	33,014
Sufficiency studies	55% [50‑60%]	126	1,085	128,852