Bifurcation of parameter K4 and ρ for RIC, [Cytokines] and [Teffector] on day 30 after infection.
a-c for parameter K4 when the value of ρ is taken as 0.0025. d-f for parameter ρ when the value of K4 is taken as 84. Red solid circles and blue squares represent severe and mild-moderate cases, respectively. The other parameters are default and are shown in Table A in S1 Text. The gray region indicates a bistable status for mild-moderate and severe cases.