COVID-19 fatalities, latitude, sunlight, and vitamin D

Am J Infect Control. 2020 Sep;48(9):1042-1044. doi: 10.1016/j.ajic.2020.06.193. Epub 2020 Jun 26.


Background: Since Vitamin D is known to be vital in regulating the immune system, and sunlight UV radiation exposure on the skin produces Vitamin D and UV intensity is highest nearest the equator, a study was done to examine the correlation between the latitude and COVID-19 fatality rates for countries.

Methods: Eighty-eight countries were selected based on their likelihood of providing reliable data. Using death rates/million for each country from the "worldometer" website, a correlation analysis was done between death rates and a country's latitude.

Results: A highly significant, positive correlation was found between lower death rates and a country's proximity to the equator (Pearson r = 0.40 P < .0001, 2-tailed t test). The R squared of 0.16 means that 16% of the variation in death rates among nations is accounted for by the latitude of the country. Evidence is presented suggesting a direct correlation between sunlight exposure and reduced mortality.

Discussion: This study is the first to document a statistically significant correlation between a country's latitude and its COVID-19 mortality and is consistent with other research regarding latitude, Vitamin D deficiency, and COVID-19 fatalities. Limitations of this study are noted.

Conclusions: Further research is needed to confirm the correlation between latitude and COVID-19 fatalities, and to determine the optimum amounts of safe sunlight exposure and/or vitamin D oral supplementation to reduce COVID-19 fatalities in populations that are at high risk for vitamin D deficiency.

Keywords: Death rates; Insufficient vitamin D; Proximity to the equator; UV radiation.

MeSH terms

  • Betacoronavirus*
  • COVID-19
  • Coronavirus Infections / blood
  • Coronavirus Infections / mortality*
  • Coronavirus Infections / virology
  • Female
  • Geography
  • Global Health / statistics & numerical data*
  • Humans
  • Male
  • Pandemics
  • Pneumonia, Viral / blood
  • Pneumonia, Viral / mortality*
  • Pneumonia, Viral / virology
  • Radiation Exposure / analysis
  • SARS-CoV-2
  • Sunlight*
  • Vitamin D / blood*
  • Vitamin D Deficiency / mortality
  • Vitamin D Deficiency / virology


  • Vitamin D