Many of the herbs and foods that are typically good for viral infections work by stimulating cytokine release in our bodies. This is an inflammatory response that helps to kill viruses and bacteria and normally this is a good thing. With some viruses such as coronavirus, bird flu, swine flu, and others, the virus itself stimulates cytokine release to very high levels, causing huge amounts of inflammation that damage the cells in the lungs, causing cell death, fluids to be released, and allows the infection to spread into the blood (sepsis). This is a "cytokine storm" that is a big part of what's killing people with this virus. Others have posed links that are good and are probably more accurate.
From what I've read and understand, the foods and herbs that are typically good for us such as mushrooms, fermented foods, elderberry, astragalus, echinacea, spirulina, chlorella, and ginger also stimulate cytokine release. I intend to avoid them at all costs if I start to feel sick.
The foods and herbs that I plan to focus on that are supposed to help with viruses but either don't stimulate cytokines or actually reduce them are: fresh apples, garlic, fresh onions, green tea (antiviral yet reduces cytokine production), turmeric, quercetin (supplements and foods that contain it), resveratrol (supplements and foods that contain it such as red wine....), vitamin C, and zinc.
My Traditional Chinese Medicine teacher suggests that if we get sick it would be a good idea to stop eating meat, dairy, wheat or any other mucus containing foods and focus on vegetable soups, chicken, fish, fruit. That's a healthy diet to me no matter what so I'm good with that.
I hope this helps. We're all learning during these difficult times. I hope that as people recover and figure out what worked well for them that they will share that also. Every bit helps.
I forgot to add that I am currently eating mushrooms, fermented foods and ginger now to keep my immune system strong, but if I start to get sick and it goes beyond just the initial stages, I will take those out of my diet to reduce the potential for overstimulation of the immune system. This is what I've learned in my Chinese Medicine (TCM) courses also - treatment at the beginning of a disease can be very different later on in the progression of a disease. Pearl also mentioned this.