Fig. 1.

Function $y_1(t)$ of strain 1 carriers, when the second strain is absent ($p_2=0$) for $u(0)=0.8$ (solid) and for $u(0)=0.7$ (dashed). The parameters are $p_1=0.15$, $y_1(0)=0.01$, the average duration of the virus carrier $T_1=15$ days