Infectious Disease Control by Vaccines Giving Full or Partial Immunity

We use a simple Lotka-Volterra model of the disease transmission process to analyse the dynamic population structure when a vaccine is available at a constant price through time which gives partial immunity to the disease. In contrast to earlier results for the full immunity case, we find that there may be multiple stationary states and instability. In contrast to earlier work which has only considered policies in steady states, we consider the dynamic effects of different dynamic vaccination policies on any solution path for the case of publicly subsidised vaccines. We find that in the partial immunity case a procyclical policy is desirable but for the full immunity case a countercyclical policy is desirable.