What is the immune response? What is immunity?
An immune response is the reaction your body gives (to any foreign invader).
Immunity is your own system's defense (native immunity, innate immunity) against invaders (pathogens). It ensures "recognition" of what is native and what is "foreign," and what can then be either tolerated or eliminated.
How does that work? This is explained here.
Taking good care of your gut microbiome (intestinal bacteria) contributes to long-term health protection.
When its composition is disrupted—for example, by poor diet, excessive use of antibiotics (directly or indirectly), or other medications such as pills and injections—the risk of disrupting your innate immunity increases, increasing the risk of illness and can lead to the development of autoimmune diseases.
Antibiotics taken to kill harmful bacteria unfortunately also damage these gut bacteria, resulting in reduced (compromised) immunity.
Overweight/obese people have a disrupted gut microbiome composition and risk triggering a cytokine storm in the event of an infection. This often leads to ARDS (Acute Respiratory Distress Syndrome), resulting in ICU admission and/or death.
Especially in Western countries - where the gut microbiome is affected by Western eating habits - the number of autoimmune diseases has increased dramatically. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056765/
SARS-COV-2
There is a correlation between how well one responds to a Covid infection and the composition of one's gut microbiome and the number of cytokine storms. The better the composition of your gut microbiome, the stronger your immunity, and the lower your risk of illness. https://gut.bmj.com/content/70/4/698
Maintain a healthy diet, consisting primarily of unprocessed plant foods:
fruit
vegetables
legumes
nuts and seeds
grains
eat enough fiber.
Avoid as much as possible:
processed products, as they boost bad bacteria and suppress good ones,
antibiotics – directly and indirectly (animal-based foods are often loaded with antibiotics),
foods of animal origin (meat, fish, dairy, and eggs), as these foods damage the composition of your gut microbiome.