Research on safety strategies for nucleic acid testing in sudden epidemic conditions based on a SEIARD dynamic model

Abstract

Infectious diseases have caused enormous disasters in human society, and asymptomatic carriers are an important challenge in our epidemic prevention and control process. Nucleic acid testing has played an important role in rapid testing for asymptomatic individuals. How to carry out nucleic acid testing in a scientific manner is a practical problem encountered in normal production and life. Based on the real COVID-19 epidemic data from Shanghai, we established a susceptible-exposed-infected-asymptomatic-recovered-death (SEIARD) dynamic model. The least squares method was used to fit the data and estimate the unknown parameters β and E(0) in the model, and MATLAB software was employed to simulate the development of the epidemic. The data fitting results indicated that the SEIARD model can better describe the early development patterns of the epidemic (R² = 0.98; MAPE = 2.54%). We calculated the basic reproduction number of the Shanghai epidemic as R₀ = 2.86. As the frequency of nucleic acid testing increased, the basic reproduction number R₀ continued to decrease. When there is one latent carrier and one asymptomatic carrier in the nucleic acid testing team, the number of queues is directly proportional to the number of infected individuals, the nucleic acid testing team increases by 50 people, and the number of new asymptomatic cases increases by approximately 4 people. If both susceptible individuals (S) and asymptomatic patients (A) are not wearing masks, the infection rate reaches approximately 7%; after wearing masks, the final infection rate is less than 1% at 1.5 m between two people. The queue spacing is inversely proportional to the number of infected individuals. With a distance of d = 1 m, a nucleic acid testing team of 100 people added 8% of the infected individuals; when d = 1.5 m, fewer than 2% of the newly infected individuals. The results confirmed that controlling the queue size for nucleic acid testing, strictly wearing masks, and maintaining a queue spacing of more than 1.5 m are safe and effective nucleic acid testing strategies. Our findings are also applicable to the prevention of other newly emerging infectious diseases.

Keywords: Infectious diseases; Nucleic acid testing; SEIARD model; Simulation.

Fig. 1

SEIAR model with asymptomatic infected individuals.

Fig. 2

Fitting of the confirmed case recovery rate function.

Fig. 3

Fitting results of daily new confirmed cases, new asymptomatic patients, cumulative confirmed cases, and cumulative removed cases in Shanghai from March 19 to April 30, 2022.

Fig. 4

Trend of basic reproduction number changes with nucleic acid testing frequency (1/day).

Fig. 5

Changes in the number of new asymptomatic infections among patients with different incubation periods.

Fig. 6

Changes in the number of new asymptomatic infected individuals under different queue spacings.

Fig. 7

Changes in the number of new asymptomatic infected individuals under different queue sizes.