A general model is presented of a disease in which both recovered and vaccinated individuals are protected from acute disease, but are still susceptible to chronic infection. The special threshold conditions for the establishment and persistence of such a disease are derived and explained in full. The efficacies of alternative vaccination strategies are detailed and a specific example of such a disease is given by examining feline calicivirus (FCV), a cause of upper respiratory tract disease in cats.
Copyright 1998 Academic Press Limited.