That article does cover a lot of good things, but it mentioned vitamin D almost as a side note.
Various articles point to studies that seem to indicate that vitamin D might be the first line of defense against respiratory viral infections, including coronaviruses.
Staying active, as this article suggests, is a good thing, but do that outside, not at the recreation center. Our bodies create vitamin D with exposure to sunlight. Also, research and eat foods high in vitamin D. It might not hurt to take a vitamin D supplement, too. I take 5,000 iu each day with my pill regimen, but vitamins from food are best, since they include the whole package and not just the extracted and processed target vitamin.
It's the same with vitamin C. Eat citrus, bell peppers, and so on. Ascorbic acid, which is in many supplements, might not have the extras you can get and need from the foods.
Garlic is a natural anti-biotic, and it scares vampires A lot can also keep other people away, as an aid for social distancing.
The jalapeño became a staple several years ago. Quite the nutrition package, vitamins, minerals, fiber, etc. It's one of the few items I buy that has actually gone down in price over time, now hovering between 58 and 68 cts/lb.
My other power house of nutrition, from the controversy corner: the egg. A lot of conflicting reports about postive/negative health effects, but my reason for adopting it into my diet was that it's low cost/high nutrition helped me survive an extreme financially lean time.
Important health element, which can be a little riskier now, depending on where you live: walking
I find that working from home right now is encouraging less movement, allowing fluids to build up in my legs. I have to be more aware of the time and walk around the apartment complex a few times a day.