Editorial: low population mortality from COVID‐19 in countries south of latitude 35 degrees North – supports vitamin D as a factor determining severity. Authors’ reply

Mayur Garg, Aysha Al‐Ani, Hannah Mitchell, Philip Hendy, Britt Christensen

First published: 30 April 2020


We  read  with  interest  the  comments  by  Rhodes  et  al,  and  Panarese  and  Shahini,  regarding  a potential association between vitamin D levels and risk of severe coronavirus-19 disease (COVID-19). Their cogent arguments regarding low dose vitamin D supplementation during a period of lockdown, particularly in areas of low sunlight exposure and low baseline vitamin D levels, appear reasonable in the context of bone protection. However, whether this association carries forward to a protective effect against severe COVID-19 remains tenuous, and best regarded with caution.

Vitamin D has been associated with multiple cellular processes implicated in innate and adaptive immunity, and  multiple  disease  associations  with  vitamin  D  deficiency  have  been  noted. However,  despite  more  than  a  decade  of  interventional  clinical  studies,  few  have  supported vitamin D supplementation for altering clinical outcomes for patients with inflammatory disease. Variable study methodology, including dose and method of vitamin D administration, or target 25-hydroxy vitamin D levels, may have contributed to the many negative studies to date. However, it is more likely that laboratory data and clinical associations have failed to translate to causality or meaningful therapy.

The  data  regarding  north-south  gradient  and  outcomes  of  COVID-19  outlined  by  Panarese  and Shahini, and Rhodes et al must be interpreted in the context of public health measures, population density,  urban  connectivity  and  spread  of  COVID-19 across  various  countries.  Strict  physical distancing  and  shutdown  measures  were  implemented  much  earlier  in  Australia (where  a  large proportion  of  the  population  lives  in  a  latitude  below  32  degrees  south),  New  Zealand  and Norway, accounting  for  improved  outcomes.  In  comparison,  countries  with  relatively  high sunlight  exposure  such  as  Indonesia, Morocco  and  Egypt,  are  currently  experiencing  high  case-fatality rates (CFRs). Singapore, which acted swiftly, is currently experiencing a surge in cases. Different  practices  in  testing  for  the  virus  and  in  reporting  medical  outcomes  will  also  skew  comparison  of  mortality  figures  between  nations.  Furthermore,  until  cross-sectional  antibody testing has been performed, CFRs will exclude undiagnosed asymptomatic patients and are likely to be gross overestimates that should be interpreted with care.

It may be premature to suggest widespread  vitamin D  supplementation with  the aim to improve outcomes  from  COVID-19.  It would  be  reasonable,  however,  to  consider  vitamin  D supplementation  to  protect  musculoskeletal  health  in  those  at  risk  of deficiency  due  to  being housebound,  as  recommended  currently  by  the  UK  National  Health  Service  (NHS  online). Additionally,  measured  recommendations  for  a  balanced  nutritious  diet,  physically  distanced exercise  and  sunlight  exposure may be better for overall physical and mental health  during  this global crisis.


Wiley – DOI: https://doi.org/10.1111/apt.15796