I wrote this as part of an unrelated series of musings on how to best characterize mixtures of microorganisms from complex samples. Those musings remain so, but I thought the below was worth sharing. Dysbiosis is defined as a dysregulation of the gut microbiome such that its composition is altered, and this has negative impacts on the host organism.
Might also be useful for the study of bacteria that form biofilms which may keep out viruses in mucosal surfaces like lung, nasal, throat, or intestinal tissues: which bacteria are consistently positively or negatively associated with viral presence or infection and which form capsular material that might affect the ability of viral particles (like a coronavirus particle in the lungs) to infect? Does the gut-lung axis affect the composition or thickness of lung mucus, so making it more difficult to traverse in some patients but not others, and since gut microbiome composition is associated with so many pathologies (diabetes, heart disease, lung disease, obesity, psychological conditions, cancers, inflammatory diseases) might this by why there is a relationship between these pathologies (which may come with dysbiosis) and susceptibility to novel coronavirus as well as severe cytokine storms?
Your gut microbiome composition is affected by a lot of factors: sleep cycles, stress, diet, age, general health, exercise, and probably also your genetic makeup. This is still an emerging field of study and the complexity is appreciated but has not yet been untangled, so people marketing products claiming “this product boosts the immune system” are basically only doing that- marketing products. Beware of hype (and in the case of your immune system, making it more active might result in autoimmune disorders, so you really want to talk to an immunologist if you are concerned about your immune function- not some quack selling pills).
That being said, if it is possible for you to take healthy measures, like increasing exercise if you get too little, eating more colorful fruits and vegetables, getting consistent and adequate sleep, and managing stress in a healthy way, this would be expected to alter the composition of your gut microbiome if consistently applied, and it is known that these measures will help your general health (just ask your doctor). It’s never too late to take up healthy habits.