Disclosed is the use of an immunogen that induces an immune response against P. gingivalis in the manufacture of a medicament for reducing the incidence or severity of a disease or condition in a subject who has received, or is receiving an anti-inflammatory agent to minimise inflammation of oral tissue of the subject and/or an antimicrobial agent to remove microorganisms and fragments thereof from oral tissue of the subject wherein the disease or condition in the subject is one that is associated with the presence of P. gingiva/is in oral tissue of a subject.
