This is besides the point but rabies doesn’t really ever get “cured” it’s fatal in 99% of cases (once symptoms begin). However because the rabies virus is dormant for a little bit (has a long latent period), you can get the vaccine after you are bit, and while you are infected. During this dormancy period, before your symptoms start, if you get the vaccine, your immune system will create antibodies to destroy the latent pathogen.

TLDR: your immune system can forget the response if the virus mutates too much since your last vaccine but since you get the vaccine even after the virus begins infection, most of the time you just need to get a shot immediately after getting bitten, kinda like tetanus shots.

Hope this helps a bit