Further to Ulfberg & Stehlik’s letter of September 29th, further evidence supports the role of Se in COVID-19 virulence(Reference Ulfberg and Stehlik1). In their pre-print analysis by machine learning of Medicare patients, Dun et al. found that the leading comorbidity associated with COVID-19 mortality, adjusted for age and race, was sickle cell disease (aOR, 1·73; (95 % CI 1·21, 2·47)), followed by chronic kidney disease (aOR, 1·32; (95 % CI 1·29, 1·36))(Reference Dun, Walsh and Bae2).
Both SCD and kidney disease can lower Se levels by decreasing tubular Se resorption and are associated with deficient Se status(Reference Delesderrier, Cople-Rodrigues and Omena3,Reference Iglesias, Selgas and Romero4) .
Se status or intake has been correlated with COVID-19 outcomes, including mortality and recovery rates, in four patient groups in China, Germany, South Korea and southern India(Reference Zhang, Taylor and Bennett5–Reference Majeed, Nagabhushanam and Gowda8). SARS-CoV-2, like other RNA viruses, sequesters Se causing Se levels to drop during infection(Reference Moghaddam, Heller and Sun6,Reference Wang, Huang and Sun9) . SARS-CoV-2 may infect cells in bone marrow, supressing red blood cell formation(Reference Reva, Yamamoto and Rasskazova10). Se status is inversely associated with haemolysis in SCD and may both inhibit haemolysis and enhance erythropoiesis in SCD(Reference Delesderrier, Cople-Rodrigues and Omena3,Reference Jagadeeswaran, Lenny and Zhang11) .
Se is required for the actions of both vitamin D and dexamethasone(Reference Schütze, Fritsche and Ebert-Dümig12,Reference Rock and Moos13) . Se infusion is safe, including in critically ill and dialysis patients, and Se supplementation has had favourable effects in other RNA virus infections(Reference Zhao, Yang and Mao14–Reference Steinbrenner, Al-Quraishy and Dkhil16).
It should be noted that vitamin C and Mg are also commonly deficient nutrients and are required for the activation of vitamin D3 by hydroxylation(Reference Cantatore, Loperfido and Magli17–Reference Cooper, Crofts and DiNicolantonio19). Deficiency of ascorbate has been associated with COVID-19 and COVID-19 outcomes in hospital populations(Reference Carr and Rowe20).
Se, supplemented if necessary with its cofactors in vitamin D metabolism, is proposed to be an important protective factor in the general population, but has the potential to reduce mortality from SARS CoV-2 infection in the sickle cell disease population to an even greater extent.
Acknowledgements
George Henderson reports that he has no conflict of interest to report in regard to this letter.