Self-organized wavy infection curve of COVID-19

TL;DR

This paper uses the SIQR model to explain the wavy COVID-19 infection curves in Japan as a self-organized phenomenon caused by fluctuating government policies and citizen responses.

Contribution

It introduces a two-valued infection coefficient model and classifies COVID-19 outbreaks into five types based on transmission and quarantine rates.

Findings

Wavy infection curves result from policy-induced fluctuations.

Classification of COVID-19 outbreaks into five types.

Relation between outbreak types and transmission/quarantine rates.

Abstract

Exploiting the SIQR model for COVID-19, I show that the wavy infection curve in Japan is the result of fluctuation of policy on isolation measure imposed by the government and obeyed by citizens. Assuming the infection coefficient be a two-valued function of the number of daily confirmed new cases, I show that when the removal rate of infected individuals is between these two values, the wavy infection curve is self-organized. On the basis of the infection curve, I classify the outbreak of COVID-19 into five types and show that these differences can be related to the relative magnitude of the transmission coefficient and the quarantine rate of infected individuals.