In March, as coronavirus deaths in the UK began to mount, two hospitals in northeast England began taking vitamin D readings from patients and prescribing them with extremely high doses of the nutrient. Studies had suggested that having sufficient levels of vitamin D, which is created in the skin's lower layers through the absorption of sunlight, plays a central role in immune and metabolic function and reduces the risk of certain community-acquired respiratory illnesses. But the conclusions were disputed, and no official guidance existed. A French experimental study at a nursing home with 66 people suggested that taking regular vitamin D supplements was "associated with less severe Covid-19 and a better survival rate". A study of 200 people in South Korea suggested that vitamin D deficiency could "decrease the immune defences against Covid-19". Preliminary research by Queen Elizabeth Hospital foundation trust and the University of East Anglia found a correlation between European countries with low vitamin D levels and coronavirus infection rates. A Spanish study ... came close to incontrovertibly proving low vitamin D levels have a pivotal role in causing increased death rates. 50 patients with Covid-19 were given a high dose of vitamin D, while another 26 patients did not receive the nutrient. Half of patients who weren't given vitamin D had to be placed in intensive care, and two later died. Only one patient who received vitamin D required ICU admission, and they were later released.