REsCue trial: Randomized controlled clinical trial with extended-release calcifediol in symptomatic COVID-19 outpatients.

Nutrition (Burbank, Los Angeles County, Calif.). 2023;107:111899

Plain language summary

Literature shows that vitamin D repletion may reduce the risk for infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mitigate severity of coronavirus disease (COVID-19), and accelerate recovery. Sufficient serum level of 25-hydroxyvitamin D (25D) is postulated to potentiate COVID-19 vaccine effectiveness, boost innate and control adaptive immunity, and reduce post-infection cytokine storm and lung injury. The aim of this study was to evaluate the safety and efficacy of extended-release calcifediol capsules to treat symptomatic patients infected with SARS-CoV-2. This study is a multicentre, randomised, double-blind, placebo-controlled phase 2 clinical trial titled REsCue. One hundred seventy-one symptomatic COVID-19 outpatients participants were enrolled. Patients were randomised (1:1) to 4 weeks of treatment with extended-release calcifediol (30 mcg/capsule) or matching placebo and a 2-week follow-up. Results show that extended-release calcifediol treatment was effective in increasing serum 25D levels to ≥50 ng/mL, which may have yielded significantly shorter resolution times for three aggregated respiratory symptoms (trouble breathing, chest congestion, and dry or hacking cough) commonly observed in patients with mild to moderate COVID-19. Authors conclude that the positive findings from this study warrant confirmation in additional larger studies.


OBJECTIVES This double-blind randomized controlled trial investigated raising serum 25-hydroxyvitamin D (25D) with extended-release calcifediol (ERC) on time to symptom resolution in patients with mild to moderate COVID-19. METHODS COVID-19 outpatients received oral ERC (300 mcg on days 1-3 and 60 mcg on days 4-27) or placebo (NCT04551911). Symptoms were self-reported daily. Primary end points were raising 25D to ≥50 ng/mL and decreasing resolution time for five aggregated symptoms (three respiratory). RESULTS In all, 171 patients were randomized, 160 treated and 134 (65 ERC, 69 placebo) retained. The average age was 43 y (range 18-71), 59% were women. The mean baseline 25D was 37 ± 1 (SE) ng/mL. In the full analysis set (FAS), 81% of patients in the ERC group achieved 25D levels of ≥50 ng/mL versus 15% in the placebo group (P < 0.0001). In the per-protocol (PP) population, mean 25D increased with ERC to 82 ± 4 (SE) ng/mL (P < 0.0001) by day 7; the placebo group trended lower. Symptom resolution time was unchanged in the FAS by ERC (hazard ratio [HR], 0.983; 95% confidence interval [CI], 0.695-1.390; P = 0.922). In the PP population, respiratory symptoms resolved 4 d faster when 25D was elevated above baseline level at both days 7 and 14 (median 6.5 versus 10.5 d; HR, 1.372; 95% CI, 0.945-1.991; P = 0.0962; Wilcoxon P = 0.0386). Symptoms resolved in both treatment groups to a similar extent by study end. Safety concerns including hypercalcemia were absent with ERC treatment. CONCLUSION ERC safely raised serum 25D to ≥50 ng/mL in outpatients with COVID-19, possibly accelerating resolution of respiratory symptoms and mitigating the risk for pneumonia. These findings warrant further study.

Lifestyle medicine

Fundamental Clinical Imbalances : Immune and inflammation
Patient Centred Factors : Mediators/COVID-19
Environmental Inputs : Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood
Bioactive Substances : Vitamin D ; Calcifediol

Methodological quality

Jadad score : 5
Allocation concealment : Yes


Nutrition Evidence keywords : Vitamin D ; Calcifediol