“They can help the immune system identify pathogens in the body so helping the immune system recognize the virus in the body and they also are part of the immune system and the mechanism that blocks the viruses from being able to get into the cells,” said registered dietitian Erin Gussler. It turns out more than 80% of those patients were deficient in vitamin D and 47% of the general population had a deficiency. The higher percentage of vitamin D deficiencies among hospitalized COVID-19 patients suggests an association -- however they did not find a relationship between vitamin D levels and the severity of their coronavirus infections. This aligns with another study of 489 patients from the University of Chicago Medicine that found there could be an association between vitamin D deficiency and the likelihood of catching coronavirus. Nonetheless, given the mounting data, it is a good idea to correct any deficiency in vitamin D.