Is urban malnutrition feeding cytokine storms in COVID-19 patients? Vitamin D insufficiency, a Hong Kong perspective
Published in Hong Kong Institute of Allergy Spring Newsletter April 2022.
The 5th Wave of SARS COVID-19, predominantly the Omicron variant, hit Hong Kong hard with unprecedented hospital admissions and mortality in the vulnerable. By mid-March 2022, 1,900 children were admitted with 2 yrs. and younger, being the highest proportion in PICU. Sudden complications, some fatal were reported with fainting, coma and convulsions. Over 6555 elderlies have succumbed.
Clinical presentations of COVID-19 include symptoms of viral infection and the life-threatening auto-immune response to the invasion. Termed ‘Cytokine storm’, this uninhibited release of inflammatory factors by the patient’s immune system is comparable with a raging forest-fire destroying without precision. The T-cells becoming overactive have been implicated in excessive inflammatory cytokine release.
Presence of Vitamin D3 in the body at normal levels (30ng/ml or 75nmol/L) supports the healthy maturation of the immune system. VitD enhances cellular immunity in young children, importantly the regulation and differentiation of T cells.
A 2018 study had shown 22-60% of HK infants had severe VitD deficiency below 25 nmol/L (10ng/ml). Recent data published by HKU for the HK paediatric population found evidence of a progressive decline in serum 25(OH)D levels since social distancing measures first began in 2020 COVID-19 pandemic.
By Nov 2021, VitD Levels were found to be declining at the rate of 6.32nmol/L per month and this is from an already lower baseline. Pregnant and breast-feeding mothers would also have a lower VitD levels due to reduced sun exposure unless supplemented. Seventy-two percent of Hong Kong young adults were VitD deficient in 2017.17 Vitamin D receptor polymorphisms which may cause dysfunction and VitD deficiency have been reported at a higher incidence in Chinese ethnicity including in Hong Kong.
Having present-day data of local deficiency, evidence from global studies and proof of healthy VitD levels in immune modulation, swift action is warranted to improve this easily modifiable factor in the war against COVID-19. The youngest age group and others, not eligible for COVID-19 vaccines are left further immunocompromised if VitD deficient. Presently there is no known program of Vitamin D supplementation for the Hong Kong adult, elderly or paediatric population. As social distancing measures continue, urgent targeted therapeutic supplementation is needed to support immune regulation. Improvement of the VitD status of the Hong Kong population will be a cost-effective, ethical measure to support reduction of severe illness and hospitalizations during the COVID-19 pandemic and future viral illnesses.
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