I don’t buy this for a second.
If people would just take Vitamin D and some other vitamins/minerals, it would help them immensely.
It is a proven fact that overall health follows income/wealth in Western nations. This has been shown by numerous studies. The rate of obesity, diabetes, alcoholism, smoking, and drug usage is much higher among the poor than the middle class.
There are also other major factors when it is examined statistically. The poor are less likely to go to the doctor until the health issue is severe (this is a big one for mortality - cancer and heart disease). They are less likely to exercise. Their diet and overall nutrition tends to be very poor by choice - more junk food, sugars (diabetes), and lower quality food.
There is also an argument based on demographics that the poor typically receive lower health care quality - they are far less likely to go to their general practice doctor who is familiar with their health history - they tend to go to walk-in clinics and the ER.
All of this is well documented by hundreds if not thousands of studies here in the US, in Europe, and in Asia.
The fact that “Covid” follows these trend lines should not be a surprise to anyone.
Life for every person is dictated by their personal choices.
I would make an anecdotal observation about Covid that is interesting and frankly is very surprising to me. The incidences of Covid among our homeless populations seems to be lower than many of us expected when this first began. Why this appears to be true is an interesting question.