Vitamin D Fails to Ease COVID, but May Lower Long COVID Risk in Adherent Users

In the VIVID randomized trial, Mass General Brigham researchers found that high-dose vitamin D3 did not reduce COVID-19 severity, hospitalizations, or transmission. However, among participants who consistently followed the supplementation regimen, there was a borderline-significant hint that long COVID symptoms eight weeks after infection were less common (21% vs 25% in the placebo group), meriting further study. The trial enrolled 1,747 COVID-positive adults and 277 household contacts across the U.S. and Mongolia, using a regimen of 9,600 IU/day for two days then 3,200 IU/day for four weeks, starting about three days after a positive test. The study, published in The Journal of Nutrition, emphasizes no clear acute benefits but suggests a potential long-COVID effect in adherent users.