My understanding on vitamin C is that without it, the immune system does not function, we cannot heal, scurvy is the result and the usual cause of death from scurvy is pneumonia.
Without vitamin C, the body in unable to produce the natural antiviral Interferon. Interferon is what "controls" the immune system and suppresses white cells (that are attracted to an infection site) from releasing the cytokines they contain that the white cells use to chemically dismantle a bacteria or virus they have enveloped. White cells locate foreign bodies because immunoglobulin sticks to them and mark them for elimination. The white cells envelop the foreign invader and dismantle it with vitamin C and cytokines that the white cells have in abundance....more than any other cell.
We can become deficient in vitamin C during an illness because viruses attempting to invade mucosal, blood or organ cells can cause extensive damage and vitamin C is used in repair along with collagen. Eventually, vitamin C levels can get low which affects Interferon levels which suppress the cytokine release from white cells. When the vitamin C and Interferon fall too low, the cytokine release occurs into the infection site as a last ditch effort to stop the infection. Cytokines are highly irritating inflammatory substances that inflame lung tissue causing edema and asthma, making breathing very difficult.
When this occurs, the patient is running out of time. Failing raw material supplies (vitamin C, B1 and B6) and collagen make it imperative that the immune system find the right immunoglobulin antibody to neutralize or kill replicating viruses before the patient succumbs to the disease.
In addition to vitamin C, vitamins A, B1, B6, D , E, zinc, selenium, iron all potentiate, provide energy for, provide raw material for or act as viral antagonists during an infection. The stronger the infection, the greater the degree of replication that is taking place (related directly to just barely adequate vitamin and mineral stores) result in rapidly falling essential chemical artillery needed by the immune system. Perfectly healthy looking people with no health compromises can have barely adequate vitamin and mineral stores which will be driven into deficiency in the face of a dangerous infection.
That the reason they become a fatality to everyone's surprise. Just enough is not good enough when you are in the fight for your life. Supplement your diet to be sure. As far as the elderly are concerned (and I'm 72 this year) most of them don't exercise and have low food intakes. Some eat poorly because they adhere to old habits and wish to do what they want. Any many, many doctors and health care professionals continue to insist that "a balanced diet is all you need" thereby fueling the belief that if you eat 3 times a day, you've covered the basics which are woefully inadequate when you are really sick with a nasty infection. The FDA's abysmally low MDR/RDA do not help the situation.
Nutrition needs differ from person to person. Its not a one size fits all situation. No surprise to me that perfectly "healthy" people die from a virus infection under a "for profit health care system" that puts money ahead of patients.
By the way, more than HALF of patients on a ventilator never recover. That's why the healthcare workers in the ICU cheer when someone beats the odds and makes it through.
Personally, I am in awe of the brave self-sacrifice that is going on in hospital ICU's, ER's and Coronavirus Wards. It saddens me to watch video of the degree that patients are suffering and just how tired and strained the health care workers: Doctors,Nurses, Inhalation Therapists, Phlebotomists, Technicians and Custodial Staff appear to be yet pick themselves up and go at it again for another extended shift, while running on empty
I wish it wasn't this way. I wish the PPE and supplies were readily at hand in abundance and I wish that the testing of all kinds was available nationwide. I wish the staffing was more than just adequate and sufficient for inevitable disasters that ALWAYS occur without much warning. It didn't have to be this way. We didn't need to repeat the horror of 1918 a second time. We were warned by very intelligent people over many years but it was more important to spend a 100 times more on an oversized military while public health was relegated to a back seat in an out of the way building laboratory.
We ignored the greatest threat to our economy, democracy and our very lives and the lives of our progeny. We ignored History and have been cursed to relive it again because of greed and stupidity.