People who are deficient in the sunshine vitamin are almost twice as likely to contract COVID-19, according to a new study.

Researchers from the University of Chicago Medicine found that patients with low levels of vitamin D, less than 20 nanograms per milliliter, had a 1.77 times greater chance of testing positive for the virus, according to their findings published in JAMA Network.

According to Insider, low vitamin D levels have been associated with increased severity of COVID-19 and a higher risk of death.

"Vitamin D is important to the function of the immune system and vitamin D supplements have previously shown to lower the risk of viral respiratory tract infections," said Dr. David Meltzer, at UChicago Medicine in a press release. "Our statistical analysis suggests this may be true for COVID-19 infection."

Global research has shown that vitamin D also affects mortality rates. Scientists found that people in countries that had the highest mortality rates from COVID-19 like Italy and Spain, also had the lowest levels of vitamin D. Conversely, the highest levels of vitamin D were found in northern European countries, like those in Scandinavia, which was among the regions with the lowest mortality rates, according to Science Daily.

High levels of vitamin D is also linked to milder illness from COVID-19. Research has indicated that vitamin D boosts the immune system to help fight viral infections and, at the same time, helps modulate the damaging cytokine storms that occur when the immune system goes into overdrive in patients with severe illness, according to Business Insider.