ABSTRACT
Objective: To explore the epidemiological characteristic of a COVID-19 outbreak caused by 2019-nCoV Omicron variant BF.7 and other provinces imported in Shenzhen and analyze transmission chains and characteristics. Methods: Field epidemiological survey was conducted to identify the transmission chain, analyze the generation relationship among the cases. The 2019-nCoV nucleic acid positive samples were used for gene sequencing. Results: From 8 to 23 October, 2022, a total of 196 cases of COVID-19 were reported in Shenzhen, all the cases had epidemiological links. In the cases, 100 were men and 96 were women, with a median of age, M (Q1, Q3) was 33(25, 46) years. The outbreak was caused by traverlers initial cases infected with 2019-nCoV who returned to Shenzhen after traveling outside of Guangdong Province.There were four transmission chains, including the transmission in place of residence and neighbourhood, affecting 8 persons, transmission in social activity in the evening on 7 October, affecting 65 persons, transmission in work place on 8 October, affecting 48 persons, and transmission in a building near the work place, affecting 74 persons. The median of the incubation period of the infection, M (Q1, Q3) was 1.44 (1.11, 2.17) days. The incubation period of indoor exposure less than that of the outdoor exposure, M (Q1, Q3) was 1.38 (1.06, 1.84) and 1.95 (1.22, 2.99) days, respcetively (Wald χ2=10.27, P=0.001). With the increase of case generation, the number and probability of gene mutation increased. In the same transmission chain, the proportion of having 1-3 mutation sites was high in the cases in the first generation. Conclusions: The transmission chains were clear in this epidemic. The incubation period of Omicron variant BF.7 infection was shorter, the transmission speed was faster, and the gene mutation rate was higher. It is necessary to conduct prompt response and strict disease control when epidemic occurs.
Subject(s)
COVID-19 , Epidemics , Male , Humans , Female , SARS-CoV-2 , COVID-19/epidemiology , Disease Outbreaks , China/epidemiologyABSTRACT
This paper proposes a millimeter-wave (mmWave) radar sensor architecture for contactless vital signs detection and monitoring at the industrial, scientific, medical (ISM) 60 GHz band. Such fast remote touchless monitoring is extremely important during pandemic seasons such as COVID-19. The architecture utilizes a leaky wave antenna to synthesize a reconfigurable radar beam whose direction is steered in the space without additional modulator circuits. The modulatorless architecture enables monitoring the vital signs of multiple patients at different locations by measuring the Doppler shifts from their movements. Furthermore, it also offers building power and cost effective sensor components by eliminating the modulator circuitry. The system considerations of the proposed architecture are discussed and the Doppler radar technique for vital signs detection is reviewed. A laboratory experiment of measuring the Doppler shift due to a vibrating target using a prototype of the proposed sensor is successfully conducted. The application of the proposed sensor can be extended to remotely scan and control running machines in industrial environments. © 2021 IEEE.
ABSTRACT
Social media has enabled misinformation to circulate with ease around the world during the novel coronavirus disease 2019 (COVID-19) pandemic. This study applies the Crisis and Emergency Risk and Communication model (CERC) to understand the themes and evolution of misinformation on the Internet during the early phases of the COVID-19 outbreak in China, when the epidemic developed rapidly with mysteries. Drawing on 470 misinformation rated as false by three leading Chinese fact-checking platforms between 1 January and 3 February 2020, the analysis demonstrated five major misinformation themes surrounding COVID-19: prevention and treatment, crisis situation updates, authority action and policy, disease information, and conspiracy. Further trend analyses found that misinformation emerged only after the nationwide recognition of the crisis, and appeared to evolve relating to crisis stages, government policies, and media reports. This study is the first to apply the CERC model to investigate the primary themes of misinformation and their evolution. It provides a standard typology for crisis-related misinformation and illuminates how misinformation of a particular topic emerges. This study has significant theoretical and practical implications for strategic misinformation management.
ABSTRACT
Objectives: This study aimed to evaluate the effect of the strategies on COVID-19 outbreak control in Shenzhen, and to clarify the feasibility of these strategies in metropolitans that have high population density and strong mobility. Methods: The epidemic feature of COVID-19 was described by different phases and was used to observe the effectiveness of intervention. Hierarchical spot map was drawn to clarify the distribution and transmission risk of infection sources at different time points. The Susceptible-Exposed-Infectious-Asymptomatic-Recovered model was established to estimate case numbers without intervention and compare with the actual number of cases to determine the effect of intervention. The positive rate of the nucleic acid test was used to reflect the risk of human exposure. A survey on COVID-19 related knowledge, attitude and behaviors were used to estimate the abilities of personal protection and emergency response. Results: The epidemic of COVID-19 in Shenzhen experienced the rising, plateau and decline stage. The case number increased rapidly at the beginning, with short duration of peak period. Although the epidemic curve showed human-to-human transmission, the "trailing" was not obvious. From the spot map, during the intervention period, the source of infection was widely distributed. More cases and higher transmission risk were observed in areas with higher population density. After the effective intervention measures, both infection sources and the risk of transmission decreased. After compared with the estimated case numbers without intervention, actual number proved the COVID-19 control strategies were effective. The positive rate of nucleic acid test for high risk populations decreased and no new cases reported since February 16. Shenzhen citizens had high knowledge, attitude and behavior level, and high protection ability and emergency response. Conclusions: Although the response initiated by the health administration department played a key role at the early stage of the epidemic, it was not enough to contain the outbreak of COVID-19. The first-level emergency response initiated by provincial and municipal government was effective and ensured the start of work resumption after the Spring Festival. Metropolitans like Shenzhen can also achieve the goals of strategies and measures for containment and mitigation of COVID-19.