Epidemiological Characteristics and Transmissibility for SARS-CoV-2 of Population Level and Cluster Level in a Chinese City

Abstract

BackgroundTo date, there is a lack of sufficient evidence on the type of clusters in which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is most likely to spread. Notably, the differences between cluster-level and population-level outbreaks in epidemiological characteristics and transmissibility remain unclear. Identifying the characteristics of these two levels, including epidemiology and transmission dynamics, allows us to develop better surveillance and control strategies following the current removal of suppression measures in China.MethodsWe described the epidemiological characteristics of SARS-CoV-2 and calculated its transmissibility by taking a Chinese city as an example. We used descriptive analysis to characterize epidemiological features for coronavirus disease 2019 (COVID-19) incidence database from 1 Jan 2020 to 2 March 2020 in Chaoyang District, Beijing City, China. The susceptible-exposed-infected-asymptomatic-recovered (SEIAR) model was fitted with the dataset, and the effective reproduction number (Reff) was calculated as the transmissibility of a single population. Also, the basic reproduction number (R0) was calculated by definition for three clusters, such as household, factory and community, as the transmissibility of subgroups.ResultsThe epidemic curve in Chaoyang District was divided into three stages. We included nine clusters (subgroups), which comprised of seven household-level and one factory-level and one community-level cluster, with sizes ranging from 2 to 17 cases. For the nine clusters, the median incubation period was 17.0 days [Interquartile range (IQR): 8.4–24.0 days (d)], and the average interval between date of onset (report date) and diagnosis date was 1.9 d (IQR: 1.7 to 6.4 d). At the population level, the transmissibility of the virus was high in the early stage of the epidemic (Reff = 4.81). The transmissibility was higher in factory-level clusters (R0 = 16) than in community-level clusters (R0 = 3), and household-level clusters (R0 = 1).ConclusionsIn Chaoyang District, the epidemiological features of SARS-CoV-2 showed multi-stage pattern. Many clusters were reported to occur indoors, mostly from households and factories, and few from the community. The risk of transmission varies by setting, with indoor settings being more severe than outdoor settings. Reported household clusters were the predominant type, but the population size of the different types of clusters limited transmission. The transmissibility of SARS-CoV-2 was different between a single population and its subgroups, with cluster-level transmissibility higher than population-level transmissibility.

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains

“…One study used case data from multiple countries around the world, 6 studies were conducted in South Korea, 4 in France, 3 in Japan, 2 in Singapore, 2 in India, 2 in Vietnam, and 2 in Australia . One hundred nineteen studies (83.8%) included patients infected with the wild-type strain, 5 (3.5%) with the multiple strains, and 11 (7.7%) with an unknown strain (eTable 4 in the Supplement).…”

“…One study used case data from multiple countries around the world, 81 6 studies were conducted in South Korea, 37 , 46 , 51 , 52 , 59 , 124 4 in France, 25 , 29 , 35 , 113 3 in Japan, 80 , 105 2 in Singapore, 87 , 111 2 in India, 16 , 78 , 83 , 103 2 in Vietnam, 21 , 58 and 2 in Australia. 45 , 99 One hundred nineteen studies (83.8%) included patients infected with the wild-type strain, 5 (3.5%) with the multiple strains, 17 , 26 , 35 , 80 , 112 and 11 (7.7%) with an unknown strain 84 , 93 , 99 , 106 , 116 , 126 , 135 , 142 , 148 , 150 , 157 (eTable 4 in the Supplement ).…”

“…We identified 5012 records through PubMed, EMBASE, and Science Direct database searches, and documented the study selection process in a flowchart and showed the total numbers of retrieved references and the numbers of included and excluded studies (Figure 1). Based on the inclusion and exclusion criteria, 142 articles (8112 patients) were selected for analysis …”

Modeling COVID-19 Transmission Dynamics: A Bibliometric Review

“…Many studies have been conducted in genomic epidemiology to find the transmission dynamics of COVID-19 in different cities and lineages of the virus [ 74 , 75 , 76 , 77 ]. These studies can see how many different lineages are responsible for affecting each city or country and which lineages are more deadly, more transmissible, and faster.…”

Perfil de transmisión del SARS COV2 en una región sanitaria del Paraguay

“…Según el Protocolo de Prevención y Control de Neumonía por Coronavirus emitido por la Comisión Nacional de Salud de China, las infecciones en "Clusters" se definen como dos o más casos confirmados o infecciones asintomáticas en un área pequeña como una familia, una unidad de trabajo, etc., dentro de los 14 días de contagio (5)(6).…”