Vitamin D3 Shows No Benefit for Acute COVID-19 Severity, Hints at Impact on Long COVID

A study by Mass General Brigham researchers found that high-dose vitamin D3 did not reduce the severity of COVID-19 infection. However, the findings, published in The Journal of Nutrition, indicated a potential impact on long COVID outcomes.

JoAnn Manson, MD, DrPH, a senior author from the Mass General Brigham Department of Medicine, noted that while the trial did not show a reduction in COVID severity or hospitalizations, a promising signal for long COVID warrants further investigation.

About the VIVID Trial

The Vitamin D for COVID-19 (VIVID) Trial was designed to clarify vitamin D's role in immune health specifically concerning COVID-19. This randomized trial included 1,747 adults who had recently tested positive for COVID-19 and 277 household contacts across the United States and Mongolia.

Participants were divided into two groups, receiving either daily vitamin D3 (beginning with an initial high dose followed by 3,200 IU/day) or a placebo, for a period of four weeks. The study employed stratified randomization and statistical weighting to ensure a balance between the groups regarding factors such as age, sex, body mass index, race/ethnicity, and COVID-19 vaccination status.

No Impact on Acute COVID-19 Severity

During the four-week study period, no significant differences were observed between the vitamin D and placebo groups in terms of healthcare utilization, which included hospitalizations, clinic visits, or emergency visits. There were also no significant variations in death rates or symptom severity.

Furthermore, high-dose vitamin D did not reduce the rate of COVID-19 contraction among household contacts of infected participants.

A Promising Signal for Long COVID

Despite the lack of impact on acute COVID-19, an analysis of participants who consistently adhered to their vitamin D regimen revealed a noteworthy signal: they were less likely to experience long COVID symptoms at eight weeks compared to the placebo group.

Specifically, 21% in the vitamin D group reported at least one persistent symptom, versus 25% in the placebo group. This difference held borderline statistical significance.

Manson highlighted the ongoing significant impact of long COVID on individuals and expressed hope that future research in larger populations could confirm if long-term vitamin D supplementation can effectively reduce the risks and severity of long COVID.