Predicting the Prevalence of COVID-19 and its Mortality Rate in Iran Using Lyapunov Exponent

Background: COVID-19 was first reported in late December 2019 in Wuhan, China, and spread rapidly throughout the world including Iran. Objective The purpose of this paper is to predict the prevalence of coronavirus and the number of confirmed cases and deaths in Iran based on the theory of chaos and measuring the Lyapunov exponent. Methods: In this analytical study, the number of confirmed cases, recovered patients, total tests, and deaths between February 20 and May 30, 2020 were collected daily from the website of the Iranian Ministry of Health and Medical Education. The prevalence rate and the time to reach saturation in a short period were estimated using a formula using Lyapunov exponent and the initial and final number of confirmed cases in Matlab software. Findings: Simulation of all confirmed cases between 20 February 2020 to 4 May 2020 show the number of people infected with the coronavirus would be close to saturation, but in end of May 2020 the number of people with the disease re-entered the second phase of increase. The slope of the simulation curve decreases in the second phase and the virus spreads in May at a slower rate than in the first phase (April). The simulation diagram of the total confirmed patients to the total number of tests performed also shows the entry into the second phase of increasing in May. Conclusion: Simulation results of all confirmed cases and total deaths in Iran, using chaos theory and the Lyapunov-based model, can properly represent the real data and can predict the trend of spread and time to approach saturation in a short time. Sensitivity to the initial condition in the equation by changing the quarantine restrictions and the observance of health protocols causes a change in the rate of total number of confirmed patients enters the third or fourth increasing phase. Also, based on the calculated deaths, it is predicted that the total number of deaths at the end of May will reach less than 5% of the total number of people who have recovered and died.