How long is a meningitis shot good for? (mcv4 is the one i got) i had one when i was 17 and im about to turn 20 so i was wondering if i need to get a new one?

These bacterial vaccines are timed to be given in preparation for those settings where the disease is more often detected. College age/military recruits/etc. The expected benefit can be up to 8 or so years. There is less need for this when the life setting is less crowded but in theory repeating won't hurt you. Insurers may not pay for the vaccine when it is not part of normal recommended use.