Evaluation of COVID-19 control strategies in differentcountries and periods based on an adaptive PSO-SEIR model

ABSTRACT

The COVID-19 pandemic has battered the world in more than 100 countries and regions due to its deadly and high transmission. How to control or limit the first and possible second wave of the infection has become an essential problem based on the control strategies implemented globally. This study presented a model to evaluate the efficiency of strategies based on an improved multi-stage SEIR (susceptible-exposed-infectious-recovered) model considering quarantine factor, treatment delay, transmission risk by the exposed, and time. The particle swarm optimization (PSO) algorithm with an adaptive weight strategy is adopted to find the SEIR model's critical parameters associated with the control strategies based on the confirmed cases, the cured cases, and the death cases in the Chinese mainland, Italy, Spain, and Germany. The model was verified by the coefficients of correlation (R2) between the predicted results using parameters found by PSO and the actual data on the confirmed, the death, and the cured cases. The R2s are all greater than 0.93 in the Chinese mainland, Italy, Spain, and Germany, showing a good accuracy of the proposed model. Base on the data of analyzed countries, PSO finds the incubation period of COVID-19 is approximately 5.1 d, which is consistent with other literatures. Besides, the period from exposure to medical care delivery is the most significant for controlling the transmission, followed by the quarantined rate according to our model. The effective reproduction number reduces from 3.9 to 1.4 while the delivery period shortens from 13 to 1 d, even without considering the effect of quarantined rate and crowd protection awareness, indicating the importance of acid testing. Moreover, the effective reproduction number is smaller than 1 when the delivery period is 1 d and the quarantined rate is higher than 0.1, which shows the transmission of COVID-19 can be contained in these conditions. Furthermore, the establishment of Fangcang shelter hospitals and the implication of aided diagnosis guideline of COVID-19 gradually reduce the period to the hospital for patients in Hubei Province from 16 to 1-2 d. In addition, the efficiency of strategies among Italy, Spain, and Germany shows that Germany reached a better condition in comparison with others, and the number of confirmed cases in each country can drop by nearly 1/3 as the protection awareness of the population rises from 0.25 to 0.69, through reducing social activities, keeping social distance, and wearing masks, indicating the importance of government advertisement, education, etc. This study might help the governments to make strategies to limit the spreading of COVID-19 or potential outbreak of emerging infectious diseases in the future. © 2021, Science Press. All right reserved.