Metastable states in plateaus and multi-wave epidemic dynamics of Covid-19 spreading in Italy

TL;DR

This paper introduces a 3D phase diagram combining Rt(t) and doubling time to analyze Covid-19 dynamics in Italy, revealing metastable states that predict the emergence of new epidemic waves and aid policy decisions.

Contribution

It presents a novel 3D phase diagram approach to characterize Covid-19 epidemic regimes and metastable states, enhancing understanding and prediction of wave transitions.

Findings

Metastable states precede new epidemic waves.

Power law relationship between doubling time and Rt.

Exponential behavior of doubling time over time.

Abstract

The control of Covid 19 epidemics by public health policy in Italy during the first and the second epidemic waves has been driven by using reproductive number Rt(t) to identify the supercritical (percolative), the subcritical (arrested), separated by the critical regime. Here we show that to quantify the Covid-19 spreading rate with containment measures (CSRwCM) there is a need of a 3D expanded parameter space phase diagram built by the combination of Rt(t) and doubling time Td(t). In this space we identify the dynamics of the Covid-19 dynamics Italy and its administrative Regions. The supercritical regime is mathematically characterized by i) the power law of Td vs. [Rt(t)-1] and ii) the exponential behaviour of Td vs. time, either in the first and in the second wave. The novel 3D phase diagram shows clearly metastable states appearing before and after the second wave critical regime. for loosening quarantine and tracing of actives cases. The metastable states are precursors of the abrupt onset of a next nascent wave supercritical regime. This dynamic description allows epidemics predictions needed by policymakers to activate non-pharmaceutical interventions (NPIs), a key issue for avoiding economical losses, reduce fatalities and avoid new virus variant during vaccination campaign