Modeling the Prevalence of Asymptomatic COVID-19 Infections in the Chinese Mainland

Abstract

Recently, considerable efforts have been focused on intensifying the screening process for asymptomatic COVID-19 cases in the Chinese Mainland, especially for up to 10 million citizens living in Wuhan City by nucleic acid testing. However, a high percentage of domestic asymptomatic cases did not develop into symptomatic ones, which is abnormal and has drawn considerable public attention. Here, we aimed to investigate the prevalence of COVID-19 infections in the Chinese Mainland from a statistical perspective, as it is of referential significance for other regions. By conservatively assuming a development time lag from pre-symptomatic (i.e., referring to the infected cases that were screened before the COVID-19 symptom onset) to symptomatic as an incubation time of 5.2 days, our results indicated that 92.5% of those tested in Wuhan City, China, and 95.1% of those tested in the Chinese Mainland should have COVID-19 syndrome onset, which was extremely higher than their corresponding practical percentages of 0.8% and 3.3%, respectively. We propose that a certain false positive rate may exist if large-scale nucleic acid screening tests for asymptomatic cases are conducted in common communities with a low incidence rate. Despite adopting relatively high-sensitivity, high-specificity detection kits, we estimated a very low prevalence of COVID-19 infections, ranging from 10 −6 to 10 −4 in both Wuhan City and the Chinese Mainland. Thus, the prevalence rate of asymptomatic infections in China had been at a very low level. Furthermore, given the lower prevalence of the infection, close examination of the data for false positive results is necessary to minimize social and economic impacts.

Contribution of Temperature Increase to Restrain the Transmission of COVID-19

“…We did not take family-cluster infections into account, which might bias our results. We also did not consider the asymptomatic COVID-19 infection cases 32 due to limited data. Further studies are still needed to investigate the relationship between asymptomatic infection and transmission of COVID-19.…”

An Optimal Nucleic Acid Testing Strategy for COVID-19 during the Spring Festival Travel Rush in Mainland China: A Modelling Study

“…We set that each individual had a fixed probability of being infected every day, with a slightly increased risk on the day of travel [ 17 , 18 ]. Based on a previous estimation [ 19 ], the COVID-19 daily incidence was set at 20 per 10,000,000 persons. The daily incidence varied from 1 to 100 infections per 10,000,000 persons in sensitivity analysis.…”

“…We assumed that people who were symptomatic or had tested positive for COVID-19 were adhering to self-isolation guidelines and were avoiding travel by train. According to a published study, the sensitivity and specificity of RT-PCR tests were assumed to be 80–95% and 99.5–100% in the first two weeks after exposure, respectively [ 16 , 19 ].…”

Analysis of key factors of a SARS-CoV-2 vaccination program: A mathematical modeling approach

“…Two key initial subpopulations are those corresponding to the infected and asymptomatic, since they affect the initial dynamics of the COVID-19 pandemic under the vaccination program. We took the seven day average of the infected reported cases and then multiplied by seven days (assumed infectiousness period) and by 0.8 to obtain the initial number of symptomatic cases (assumption of the proportion of symptomatic cases in the reported cases) [17, 4, 89, 123, 23, 154, 65, 122, 44]. The percentage of asymptomatic cases in the official statistics varies for each country.…”

“…However, the detection of asymptomatic infections is possible in the case of the USA in situations in which testing is mandatory (as in some universities) or random. We approximated this value by relying on data from different studies [17, 4, 89, 123, 23, 154, 65, 122, 44]. However, in our simulations we varied the parameter through reasonable values.…”