A simple vitamin supplement could help reduce the mortality rate from COVID-19 studies show.
Vitamin D, which is produced naturally in the body from sunlight, is believed to reduce the severity of many respiratory illnesses, but studies have shown a deficiency is evident in many patients who died from COVID-19.
Studies also show death rates have been higher in countries where the population generally has lower vitamin D levels, such as parts of Europe.
While in the UK the Scientific Advisory Committee on Nutrition has been tasked with reviewing whether ethnicities such as black and Asian people, who are disproportionately represented in the COVID-19 death rates, could benefit from vitamin D supplements.
The British Medical Association has also called for a review into using vitamin D after 94 per cent of the healthcare workers who died from COVID-19 were from a black, Asian or minority ethnic (BAME) background.
Dark skin with a higher melanin level produces less vitamin D from the sun, so when people with darker skin live in a country with low rates of sunshine, such as the UK, vitamin D deficiency occurs.
Adrian Martineau, a professor of respiratory infection and immunity at Queen Mary University of London, told The Guardian deaths among BAME NHS staff had highlighted the issue of vitamin D deficiency.
"Vitamin D could almost be thought of as a designer drug for helping the body to handle viral respiratory infections," Martineau said.
"It boosts the ability of cells to kill and resist viruses and simultaneously dampens down harmful inflammation, which is one of the big problems with COVID-19."
Research done at Anglia Ruskin University in the UK showed a correlation between high COVID-19 mortality rates and low levels of vitamin D in European countries.
The study showed in Italy and Spain, where there were high mortality rates, there were low levels of vitamin D, particularly in older people who stay out of the strong sun.
The study showed there were higher levels of vitamin D in Scandanavian countries due to a diet higher in fish oils - a good source of the vitamin. These countries had a lower mortality rate.
According to the World Health Organization vitamin D can help reduce the severity of respiratory illnesses such as pneumonia, tuberculosis and bronchiolitis. It also says low levels of vitamin D can weaken the immune system.
As well as protecting against respiratory infections, vitamin D is also believed to stop white blood cells from releasing too many inflammatory cells during an infection, which has been an issue in COVID-19 patients when the virus has spread to the lungs.
A study published in the British Medical Journal in 2017, of which Martineau was one of the authors, concluded that vitamin D supplements were safe and effective in the treatment of respiratory illnesses.
However, Martineau recently told the Guardian further work was needed to see if vitamin D was effective in reducing the effect of COVID-19.
According to the Ministry of Health website around 5 per cent of Kiwis are deficient in vitamin D.
