Without going into complicated concepts, immunity is a system that has different defense components, each of which is responsible for defense against a specific type of infection.
The main components of defense against viruses are the NK (natural killers) and Th1 (T-helpers-1) cell lines. Roughly speaking, if your immune system is dominated by these components, viral infections will be easy or asymptomatic, but on the other hand there is a risk of autoimmune reactions.
Other cell lines such as B-cells (that produce antibodies), as well as Th2 (T-helpers-2) , etc. mostly "work" with bacteria, fungi, parasites, but do not cope with viruses (hi Covid:)). That is why all sorts of "measuring the strength" of immunity against viruses (or after vaccination) through antibodies is complete nonsense.
From a practical point of view, it is first of all important to determine your individual activity of some components against the background of others. For example, there are people whose immune system is good at dealing with bacteria but does not "take out" viruses, and vice versa. You can do this with an immunogram, which can be done in any civilian laboratory. This analysis will show the concentration of all major immune cells and their ratio.
Further, if we see the dominance of components that are responsible for bacteria, then we need to switch the immune system to the dominance of viral defense components. How do we do that? - Take certain supplements (google "th1 th2 supplements" and "NK cell-activating compounds")
I personally use NOW IMMUNE RENEW. However, any supplement with large amounts of Astragalus membranaceus (Astragalus membranaceus) plant extract has properties to stimulate components of the immune system's viral defenses.
Evidence citations:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8324177/
https://www.mdpi.com/2227-9059/10/2/296
https://www.nature.com/articles/s41423-021-00825-2
https://pubmed.ncbi.nlm.nih.gov/34695836/
https://pubmed.ncbi.nlm.nih.gov/15015443/
https://pubmed.ncbi.nlm.nih.gov/17361521/
https://pubmed.ncbi.nlm.nih.gov/12205961/
