Epidemic plateau in critical SIR dynamics with non-trivial initial conditions

Understand

Containment measures implemented by some countries to suppress the spread of COVID-19 have resulted in a slowdown of the epidemic characterized by time series of daily infections plateauing over extended periods of time.

• We prove that such a dynamical pattern is compatible with critical Susceptible-Infected-Removed (SIR) dynamics.
• In traditional analyses of the critical SIR model, the critical dynamical regime is started from a single infected node.
• The application of containment measures to an ongoing epidemic, however, has the effect to make the system enter in its critical regime with a number of infected individuals potentially large.