Ratio of the basic reproduction numbers. Subfigure a shows the ratio R0,rep/R0,ran(as defined in equation 1) for 1 ≤ n ≤ 20 (number of daily contacts) and τ = 14 (infectious period). Triangles stand for β·n·τ = R0,ran= 2.4, squares for R0,ran= 1.8 and circles for R0,ran= 1.2. Subfigure b gives R0,rep/R0,randepending on the infectious period τ. Red lines and symbols are for n = 4, and blue lines stand for n = 10, whereas green lines represent n = 16. The meaning of the symbols is identical as in subfigure a.