If you are infected by a virus, and subsequently survive it and get completely rid of the infection, are there any other possible reasons for the same virus to be able to infect you again any time in the future, other than the virus mutating enough to not "match" the antibodies that were created in your body during the first infection?
The background for this question is the talk among researchers about the possibility of SARS-CoV-2 antibodies possibly "not remaining in the body" forever, and the associated risk of it being possible to get infected again by this virus after a certain amount of time has passed (i.e. EVEN if the virus has NOT mutated anything at all).
This got me curious and led me to trying to find examples of viruses that can infect you twice WITHOUT any mutation of the virus in question being involved, but I did not manage to find any such examples?
My question is therefore, put in another way:
Are there any viruses that can infect you twice, WITHOUT any mutation of the virus being involved, and in that case why (by means of which mechanisms) and what are some examples of such viruses?