Fig. 4.

X axis: days. Y axis: proportion of the population infected (note different scale used for panel A). All epidemics are based on a population with 50 % A / 50 % O individuals and initialised at t = 0 with type O index cases and 1/1,000,000 of the population infected. R_max = 2 and ρ = 30 % for all epidemics modelled. A: No vaccination. B: 35.4 % of the population vaccinated at t = 0, all type A. C: 35.4 % of the population vaccinated at t = 0, all type O. D: 35.4 % of the population vaccinated at t = 0, half type A and half type O. Vaccinating O is slightly more effective than vaccinating A, but vaccinating both types leads to herd immunity at a lower threshold.