Vitamin D3 reduces COVID-19 infections that result in severe illness and significantly decreases the risk of death in at risk population
  
It was long ago demonstrated that Vitamin D3 prevents colds and influenza (1) . A meta analysis (2) published in 2017 confirmed this finding with the lead investigator, Professor Adrian Martineau from QMUL, concluding that "the reduction in risk of acute respiratory infection induced by Vitamin D was on a par with the protective effect of the flu vaccine."

Given the prevalence of COVID-19 to result in severe respiratory impairment, it is welcome news that Vitamin D3 can have an equally meaningful effect of COVID-19 infections.

Soon after the outbreak of COVID-19 pandemic in 2020, two studies suggested that the severity of the illness and the death rate caused by the virus was related to patients' level of Vitamin D. The first study from Trinity College Dublin  (3)   showed that countries where the population had higher Vitamin D levels had significantly lower rates of infection and even death. Norway and Finland, which had the highest Vitamin D levels hardly any deaths as compared to 300 deaths per million population in Spain which was found to have the lowest Vitamin D levels.

These findings are the result of Norway, Finland and Sweden, having long ago recognized the dangers of Vitamin D deficiency so supplementation and fortification of foods became widely adapted many years ago.

The correlation between low Vitamin D levels and death from COVID-19 was found to have high statistical significance. A second study conducted by Northwestern University confirmed this finding  (4)

Three additional studies have emerged and appear to confirm these important findings. The conclusions that adequate Vitamin D levels could prevent the disease becoming severe in 90% of cases and reduce patients risk of dying from the infection by 96%  (  5 ,  6 ,  7 ) 

The first study (5) was conducted in the Philippines in 212 cases with laboratory confirmed infection of COVID-19. Of these 212 cases the majority had good clinical outcomes. But Vitamin D levels were lowest in the most critically ill patients cases and highest in patients with mild symptoms. It was found that 72.8% of patients with Vitamin D levels of less than 50nmol/L had severe or critical conditions as compared to 7.2% of patients with Vitamin D levels of greater than 75nmol/L .(see detailed chart below)  The Philippines study concluded that the patient's Vitamin D level was highly significantly associated with the patient's clinical outcome.