Having low blood levels of vitamin D may not increase a person's risk for severe COVID-19, a study published Wednesday by JAMA Network Open found. People with extremely low levels of vitamin D in their blood were not more likely to test positive for antibodies to the coronavirus, the data showed. The presence of antibodies -- cells made by the immune system -- suggests past infection. Those with moderately low levels of the vitamin also did not have a higher risk for testing positive for coronavirus antibodies, the researchers said. "We found no evidence for an independent association between low...