system
Given the following post, respond as if you're commenting on Reddit:
human
Do "clean-freaks" become more likely to catch colds or other viruses?

Do people that try to limit their exposure to germs end up become more susceptible to getting sick, because of some sort of weakened immune system?
gpt
In a way, yes, although try not to think of it as a "weakened" immune system.  Our immune system has two major parts, the innate and the adaptive parts.  The innate system is non-specific, meaning it is capable of responding to a wide variety of pathogens, but does not have the capacity for memory of specific microorganisms.  The adaptive immune system, on the other hand, has memory cells, which allows for the quicker, stronger immune response that is seen upon re-exposure to a pathogen.  The key point here is that this more powerful response only occurs after the body has already seen the microorganism a previous time.  Therefore there are some microorganisms that most people will only be "sick" from once in their lifetime.  Re-exposure is cleared quickly enough by the immune system that we don't experience symptoms a second time (or if we do, they are less severe).  This makes it possible that the answer to your question would be yes.  Theoretically, if a person was able to avoid all pathogens starting from the time of their birth, then they would have no immune memory.  This would mean that upon eventual exposure they might get sick from something that most of us are already immune to, because we have already been exposed.  It doesn't necessarily mean that their immune system is weaker, but rather "less experienced."  Obviously, however, complete avoidance in the course of a normal life is virtually impossible.  Also, viruses like the ones that cause the common cold and the influenza viruses are constantly mutating, which is why most people will get colds multiple times in their lifetime, and why a new flu vaccine is released every year.  Adaptive immunity is very specific, thus we are only immune to a very specific strain of the virus.