Editorial: low population mortality from COVID‐19 in countries south of latitude 35 degrees North – supports vitamin D as a factor determining severity
Alimentary Pharmacology and Therapeutics 20 April 2020 https://doi.org/10.1111/apt.15777
Jonathan M Rhodes Sreedhar Subramanian Eamon Laird Rose Anne Kenny
VitaminDWiki
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San Marino is a microstate (pop 33,000) inside of Italy