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. 2021 Jun 23:8:591372.
doi: 10.3389/fmed.2021.591372. eCollection 2021.

Estimating the Prevalence of Asymptomatic COVID-19 Cases and Their Contribution in Transmission - Using Henan Province, China, as an Example

Chunyu Li  1 , Yuchen Zhu  1 , Chang Qi  1 , Lili Liu  1 , Dandan Zhang  1 , Xu Wang  1 , Kaili She  1 , Yan Jia  1 , Tingxuan Liu  1 , Daihai He  2 , Momiao Xiong  3 , Xiujun Li  1
Affiliations

Estimating the Prevalence of Asymptomatic COVID-19 Cases and Their Contribution in Transmission - Using Henan Province, China, as an Example

Chunyu Li et al. Front Med (Lausanne). .

Abstract

Background: Novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), is now sweeping across the world. A substantial proportion of infections only lead to mild symptoms or are asymptomatic, but the proportion and infectivity of asymptomatic infections remains unknown. In this paper, we proposed a model to estimate the proportion and infectivity of asymptomatic cases, using COVID-19 in Henan Province, China, as an example. Methods: We extended the conventional susceptible-exposed-infectious-recovered model by including asymptomatic, unconfirmed symptomatic, and quarantined cases. Based on this model, we used daily reported COVID-19 cases from January 21 to February 26, 2020, in Henan Province to estimate the proportion and infectivity of asymptomatic cases, as well as the change of effective reproductive number, R t . Results: The proportion of asymptomatic cases among COVID-19 infected individuals was 42% and the infectivity was 10% that of symptomatic ones. The basic reproductive number R 0 = 2.73, and R t dropped below 1 on January 31 under a series of measures. Conclusion: The spread of the COVID-19 epidemic was rapid in the early stage, with a large number of asymptomatic infected individuals having relatively low infectivity. However, it was quickly brought under control with national measures.

Keywords: COVID-19; asymptomatic cases; infectious dynamic model; prevention and control measures; the effective reproductive number.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Location of Henan Province (the map was created with ArcGIS software, 10.5).
Figure 2
Figure 2
Schematic diagram of SEAIUHR model propagation process. S, susceptible; E, latent; A, asymptomatic infectious; I, confirmed symptomatic infectious; U, unconfirmed symptomatic infectious; H, hospitalized; R, removed.
Figure 3
Figure 3
Comparison of the number of cases estimated and observed. The asterisk represents the number of cases with symptoms observed on a daily basis; the curve shows the change in the average number of confirmed symptomatic cases per day estimated by the model. The light blue shade was the 95% confidence interval of the estimation.
Figure 4
Figure 4
Comparison of the number of cases estimated and generated. The asterisk represents the number of cases with symptoms observed on a daily basis; the curve shows the change in the average number of confirmed symptomatic cases per day estimated by the model. The light blue shade was the 95% confidence interval of the estimation.
See this image and copyright information in PMC

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