The key difference is that polio, measels, etc do not mutate so a vaccine is very effective and a disease can cease to exist by being denied the hosts it needs to live. Meanwhile, things like the flu and Covid actively mutate, so any vaccine is aiming at a moving target. This is why the flu vaccine has such a relatively low effectiveness. Epidemiologists need to guess which strain of the flu will prevail this year and they have to do it sufficiently in advance to allow for the manufacture prior to the start of the flu season. One of the key arguments for gettung everyone vaccinated against Covid is to deny the virus hosts because it is only in the presence of a host that it can mutate. There is an excellent book by John Barry called The Great Influenza that is all about the Spanish Flu pandemic (that actually is now believed to have started in yhe US). It explains alot of the epidemiology too.