If you do not have the Plague-Bearer: Vector of Infection feature, you may take it for half the listed AXP cost.
Your diseases refuse to die out. Any diseases which you catch live within you forever, still harmless to you but able to infect those around you. You may also infect a creature with two diseases instead of one with your Plague-Bearer: Vector of Infection feature, and your Medic Save DC increases to 8 + your Wisdom modifier + your Constitution modifier + your proficiency bonus for all effects.