Scientists from the University of Barcelona showed that patients prescribed calcifediol – an intensive dose of Vitamin D usually used for people with chronic kidney failure – had their risk of admission to intensive care dramatically cut and death rates significantly lowered.
Currently the steroid dexamethasone has shown the greatest impact, reducing deaths by 30 per cent, and is now recommended for seriously ill NHS patients, but the new study suggests calcifediol could be twice as beneficial if given early.
In the study, 10 per cent of patients admitted to Barcelona's Hospital del Mar with coronavirus died within 30 days. However, while 57 out of 379 (15 per cent) control patients died, just 36 out of 551 (6.5 per cent) of those treated with calcifediol died.
The researchers found that earlier treatment was better. If given on admission to intensive care, the treatment made no difference.
The authors concluded: "Our results indicate that early calcifediol administration is critical for mortality reduction, since initiation of calcifediol during ICU admission did not modify patient survival.
"Ultimately these effects are thought to curb the inflammatory cascade that leads to the cytokine and chemokine storm associated with the pathogenesis of acute respiratory distress syndrome (ARDS). Adequate Vitamin D status could also play a role in preventing Covid-19 infection."
There has been growing speculation that one of the reasons why black, Asian and minority ethnic (BAME) communities are so disproportionately impacted by coronavirus is endemic low levels of Vitamin D in BAME populations.
The vitamin is produced naturally in the body when skin comes into contact with sunshine and is vital for healthy bones, strong muscles and a good immune system. But not as much sunlight can penetrate darker skins, meaning less of the vitamin is produced.
The NHS currently recommends that people take Vitamin D supplements in the winter.
Last year, researchers from Anglia Ruskin University published work showing a significant correlation between the number of coronavirus cases compared to average population levels of Vitamin D.
Italy and Spain have both experienced high mortality rates, and scientists found both countries have lower than average Vitamin D levels. This is partly because people in southern Europe, particularly the elderly, avoid strong sun, while their darker skin pigmentation also reduces the body's ability to produce natural Vitamin D.
In contrast, the highest average levels of Vitamin D are found in northern Europe, due to high consumption of cod liver oil and Vitamin D supplements, and possibly less sun avoidance.
Vitamin D has been shown to protect against acute respiratory infections. It also regulates the response of white blood cells, preventing them from releasing too many inflammatory cells which may stop the body overreacting to the virus.
The study was published as a preprint of The Lancet journal and is yet to be peer reviewed.
Some scientists said it was unclear whether the study was fully randomised, while others said they were concerned that people may think vitamin D would be enough to protect them from Covid and urged them to still have a vaccine.