What must an unvaccinated person's immune system do upon initial exposure to a real pathogen?

Answer

Start from scratch: identify, activate naïve cells, multiply, and produce antibodies.

An unprotected individual must initiate the entire immune process from the beginning when first exposed to a genuine pathogen, a process that consumes several days or weeks, during which illness can develop.

What must an unvaccinated person's immune system do upon initial exposure to a real pathogen?
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