Cross-national study associates low vitamin D levels with higher COVID-19-related mortality

The coronavirus disease 2109 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to wreak havoc across the globe. Since SARS-CoV-2 was first detected in Wuhan, China, in December 2019, more than 120 million cases of COVID-19 have been confirmed.

It has been reported that vitamin D supplementation can help reduce the fatal effects of COVID-19. Past studies have also tied vitamin D deficiency to increased mortality due to COVID-19.

A new study by an international team of researchers – from New York University, Abu Dhabi, the Ludwig-Maximilians-Universität, München, and Barts Cancer Institute, London – showed that there are lower COVID-19 mortality rates in countries with the most insufficient annual sun exposure, but highest mean 25-hydroxyvitamin D (25(OH)D) or vitamin D (25)-HD levels.

Study: Mean Vitamin D levels in 19 European Countries & COVID-19 Mortality over 10 months. Image Credit: FotoHelin / Shutterstock

The study, which appeared on the pre-print server medRxiv*, provides evidence for the importance of fortification with vitamin D to prevent severe complications caused by SARS-CoV-2 infection.

Vitamin D and COVID-19

Previous studies showed the plausibility of vitamin D prophylaxis and therapy for COVID-19, especially in areas where vitamin D deficiency is prominent.

Vitamin D has a potential role in preventing infections, which stems from its ability to influence innate and adaptive immune responses. There are pieces of evidence showing the link between vitamin D deficiency and increased risk of influenza infection.

However, more than a year into the coronavirus pandemic, there are no significant vitamin D trials that have been completed. Despite this, reports are demonstrating the effect of vitamin D deficiency on COVID-19 severity.

Since exposure to sunlight helps activate vitamin D synthesis in the skin, most people living in northern climates can develop deficiencies – especially in colder seasons. Diets and eating habits can also contribute to a vitamin D deficiency. In darker-skinned individuals, it is harder to metabolize vitamin D.

The study

In the study, the team aims to update recent analyses on the effects of low vitamin D levels on mortality in COVID-19 patients. They focused on the link between vitamin D (25)-HD average and COVID-19 mortality rates based on the public health record of deaths in two-week periods in 19 European countries. To arrive at the study findings, the researchers downloaded coronavirus pandemic data for the countries from “Our World in Data,” which was last updated on January 24, 2020.

Data from March 21, 2020, to January 22, 2021, were included in the statistical analyses, while data on vitamin-D (25)-HD average were collected through literature review.

The study findings showed that the crude mortality rate (CMR) elevates with decreasing mean vitamin D level. European countries with Vitamin D (25)-HD means less than or equal to 50 have increased COVID-19 death rates than those with a higher vitamin D level.

The findings highlight the importance of food fortification and vitamin D supplementation to reduce the risk of death from COVID-19. Further, vitamin D levels provide support for more awareness of its importance in preventing infections, especially COVID-19.

The data from this statistical analysis shows a strong and statistically significant association between the Vitamin D deficiency and the total number of COVID-19 deaths in the 19 European countries included in this statistical analysis,” the researchers concluded in the study.

The team emphasizes detecting people who are more likely to develop complications and die due to COVID-19. Novel vitamin D techniques to detect deficiency through the finger-prick technology can help clinicians identity patients at a higher risk of developing severe COVID-19.

To date, the number of people who died due to COVID-19 has reached 2.65 million. The United States reports the highest numbers of cases and deaths, reaching 29.47 million and 535,000, respectively.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

  • COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) –
Journal reference:
  • Ahmad, A., Heumann, C., Ali, R., and Oliver, T. (2021). Mean Vitamin D levels in 19 European Countries & COVID-19 Mortality over 10 months. medRxiv. doi:,

Posted in: Medical Science News | Medical Research News | Disease/Infection News | Healthcare News

Tags: Cancer, Coronavirus, Coronavirus Disease COVID-19, Influenza, Mortality, Pandemic, Prophylaxis, Public Health, Respiratory, SARS, SARS-CoV-2, Severe Acute Respiratory, Severe Acute Respiratory Syndrome, Skin, Syndrome, Vitamin D, Vitamin D Deficiency

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Written by

Angela Betsaida B. Laguipo

Angela is a nurse by profession and a writer by heart. She graduated with honors (Cum Laude) for her Bachelor of Nursing degree at the University of Baguio, Philippines. She is currently completing her Master's Degree where she specialized in Maternal and Child Nursing and worked as a clinical instructor and educator in the School of Nursing at the University of Baguio.

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