Effect of Vitamin D3 Supplementation vs. Placebo on Hospital Length of Stay

Not a doctor but is it perhaps not too late to start giving vitamin D3 once the patient has been admitted?

tl;dr:

"In this double-blind, randomized, placebo-controlled trial involving 240 hospitalized patients with severe COVID-19, a single dose of 200,000 IU of vitamin D3 supplementation was safe and effective in increasing 25-hydroxyvitamin D levels, but did not significantly reduce hospital length of stay (hazard ratio, 1.12) or any other clinically-relevant outcomes compared with placebo."

TLDR; covid patients were given single dose of 200,000 IU vitamin d3 or placebo. Results indicate that it didn’t mattered.