One thing to consider in this train of thought is that those antibodies and cells are not being constantly produced or maintained. This is the beauty of “immunological memory”.

These cells die off in massive numbers once you clear a pathogen (or following vaccination), leaving behind a tiny colony of memory cells that lies relatively dormant until you encounter the same pathogen (or vaccinate antigen) again.

When that happens, they multiply enormously and mount a whole new immune response, then repeat. This is basically what allows an enormous & diverse immune library.

Using the computing analogy, it’s like running a program vs storing program files. You can’t run all your programs at once, but you can store a lot of program files.

There is obviously a lot more happening in the grand scheme of immunity but hope this is easier to understand!