Multistationarity and multistability in SIRnS for n > 2

Investigate whether the SIRnS model (with n > 2 recovered classes) exhibits multistationarity and multistability; characterize parameter regimes yielding multiple equilibria and multiple stable equilibria.

Background

SIRnS generalizes SIRS by introducing multiple recovered stages and potential infectiousness during recovery, leading to richer dynamics and possible non-uniqueness of endemic equilibria.

While Hopf and bifurcation inheritance results exist, the existence and classification of multi-equilibria and multi-stability remain unresolved for higher n.