Just as Canada might be the best neighbor a country could have (secure border, similar cultural priorities), Vitamin A should be a best friend in your health supplementation.

According to an article in the Journal Aging, August 2020 (Rong Li1,*, Ka Wu2,*, Yu Li1, Xiao Liang1, William Ka Fai Tse3, Lu Yang1, Keng Po Lai1. Revealing the targets and mechanisms of vitamin A in the treatment of COVID-19; AGING 2020, Vol. 12, No. 15; August 15, 2020.)Revealing the targets and mechanisms of vitamin A in the treatment of Covid-19.pdf:

Vitamin A (VA) has potent physiological functions, such as promoting growth and reproduction and maintaining bone, epithelial tissue, vision, and normal secretion of mucosal epithelium. VA and its derivatives can prevent precancerous lesions [9]. An increasing number of reports indicate that VA is necessary to maintain immune function and that it is responsible for immune cell differentiation and proliferation [10]. It has been reported that VA can improve the ability of immune cells to produce antibodies and induce T lymphocytes to release functional lymphokines through modulation of target genes via nuclear receptors [11]. Additionally, VA is extremely important for maintaining sufficient levels of natural “killer cells” (showing antiviral activity) in circulating blood [12]. VA adjuvant therapy may enhance body immune function by increasing IgM and IgG levels and activating T lymphocytes [13]. More importantly, vitamin A was reported to play a significant role against pneumonia. It is evidenced that low VA content is linked to neonatal pneumonia [14]. Clinical data show that VA deficiency is implicated in fatal mycoplasma-induced pneumonia in children [15]. In addition, VA supplementation contributes to the reduction of clinical complications and shortening of in-hospital time for children with pneumonia [16]. 

That is all very interesting. After reading this article I was curious, what sort of people suffer most from covid, the old, yes, but that isn't something we can prevent, so who else? The diabetics, alcoholics, and obese suffer more from coronavirus than many others. If Vitamin A is an important factor in surviving coronavirus, do any of the three categories of people above suffer from a vitamin A deficiency? The answer, astonishingly, is yes, all three. In fact, the mechanism is even fairly understandable. for instance, in the case of alcohol consumption, your body processes ethanol converting it from an alcohol to an aldehyde (formaldehyde - enbalming fluid), then to an organic acid (acetic acid - vinegar) and then your body passes the vinegar out in urine. Enzymes in your liver perform the conversion of alcohol into vinegar. When you consume vitamin A, it is usually taken in the form of retinol, an alcohol. Your body converts retinol into retinoic acid, which is the form useful to your body. The same enzymatic pathway that converts ethanol to acetic acid. so, when your body is taxed by excessive alcohol consumption, the enzymes are not available to make vitamin A useful to your body. the adverse effects of alcohol on vitamin a metabolism.pdf