Here N denotes the population size of infectives and DS is the relative evolutionary entropy of the incumbent and the invader. The quantities W (the reproductive potential) and c (the demographic index) are statistical parameters, and both are functions of the agespecific fecundity and survival functions which determine the infectious net-reproductive function V (x). The parameters W and c define different scenarios for the epidemiological population biology that prevail during the competitive invasion process. These quantities, in contrast to entropy, can assume positive or negative values contingent on the geometry of the infectious net-reproductive function. The demographic index, c, relates to the flatness or peakness of the infectious net-reproductive function V (x): generally speaking cv0 implies a peaked net-reproductive function, whereas cw0 implies it is flat. This term is less influential on the dynamics as it is scaled by 1=N, so when N (the number of infectives) is moderately largẽ s s~{WDS; so competitive advantage is now determined by the relative entropy and the reproductive potential.