Boston researchers are studying another potential weapon in the coronavirus fight.

Brigham and Women’s Hospital will look at whether vitamin D can lessen the severity of COVID-19 symptoms.

Researchers are also studying whether vitamin D supplements reduce the chance of becoming infected if you have been exposed to someone in your household who tested positive for COVID-19.

Vitamin D is already known as an immune system booster.

The study ( https://www.vividtrial.org/) will focus on patients age 30 or older who have been recently diagnosed with the virus within the previous five days.

Participants will be asked to take the vitamin D or placebo study capsules every day for 28 days, provide at-home blood samples by fingerprick and complete questionnaires.

Studies have suggested that vitamin D may reduce the risk of respiratory tract infections.

Researchers said, “the potential role of vitamin D to protect against infection by the novel coronavirus that leads to COVID-19 is promising but unknown.”