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1.
Journal of Shandong University ; 58(10):95-99, 2020.
Article in Chinese | GIM | ID: covidwho-1975282

ABSTRACT

Objective: To investigate the transmission characteristics of a family cluster outbreak of coronavirus disease 2019 (COVID-19) in Xi-an, in order to provide reference for prevention and control efforts.

2.
J Clin Microbiol ; 58(8)2020 Jul 23.
Article in English | MEDLINE | ID: covidwho-999206

ABSTRACT

The outbreak of coronavirus disease 2019 (COVID-19) has spread across the world and was characterized as a pandemic. To protect medical laboratory personnel from infection, most laboratories inactivate the virus causing COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in clinical samples before testing. However, the effect of inactivation on the detection results remains unknown. Here, we used a digital PCR assay to determine the absolute SARS-CoV-2 RNA copy number in 63 nasopharyngeal swab samples and assess the effect of inactivation methods on viral RNA copy number. Viral inactivation was performed by three different methods: (i) incubation with the TRIzol LS reagent for 10 min at room temperature, (ii) heating in a water bath at 56°C for 30 min, and (iii) high-temperature treatment, including autoclaving at 121°C for 20 min, boiling at 100°C for 20 min, and heating at 80°C for 20 min. Compared to the amount of RNA in the original sample, TRIzol treatment destroyed 47.54% of the nucleocapsid protein (N) gene and 39.85% of open reading frame (ORF) 1ab. For samples treated at 56°C for 30 min, the copy number of the N gene and ORF 1ab was reduced by 48.55% and 56.40%, respectively. The viral RNA copy number dropped by 50 to 66% after heating at 80°C for 20 min. Nearly no viral RNA was detected after autoclaving at 121°C or boiling at 100°C for 20 min. These results indicate that inactivation reduced the quantity of detectable viral RNA and may cause false-negative results, especially in weakly positive cases. Thus, use of the TRIzol reagent rather than heat inactivation is recommended for sample inactivation, as the TRIzol reagent had the least effect on the RNA copy number among the tested methods.


Subject(s)
Betacoronavirus/drug effects , Betacoronavirus/radiation effects , Disinfection/methods , RNA, Viral/analysis , Specimen Handling/methods , Virus Inactivation/drug effects , Virus Inactivation/radiation effects , Adolescent , Adult , Aged , Aged, 80 and over , Disinfectants , Female , Gene Dosage , Hot Temperature , Humans , Male , Middle Aged , Polymerase Chain Reaction , RNA, Viral/genetics , SARS-CoV-2 , Young Adult
3.
China Tropical Medicine ; 20(9):853-856, 2020.
Article in Chinese | GIM | ID: covidwho-890728

ABSTRACT

Objective: To explore the transmission characteristics of the typical clusters of coronavirus diseases 2019 (COVID-19) in Xi'an, so as to provide scientific basis for optimizing the control strategy of COVID-19.

4.
Chinese Journal of Nosocomiology ; 30(6):834-838, 2020.
Article in Chinese | GIM | ID: covidwho-822403

ABSTRACT

OBJECTIVE: To explore the early features of COVID-19 epidemic in Shaanxi Province so as to provide scientific basis for optimizing the prevention strategies and evaluating the effects of interventions. METHODS: The epidemic data that were reported through official networks of Shaanxi Province from Dec. 31, 2019 to Feb. 13, 2020 and the case data from Chinese Information System for Disease Control and Prevention were collected, the population data during the same period were obtained from Shaanxi Statistical Yearbook. The descriptive epidemiological analysis was performed by using Excel and ArcGIS software, the transmission dynamics model of COVID-19 was built based on Berkeley Madonna software experiment platform, and the rules of occurrence and progression of the disease were observed. RESULTS: By Feb. 13, 2020, the accumulative confirmed cases of COVID-19 reached 230 in Shaanxi Province, and the incidence rate was about 0.59 per 100 000. The male cases were more than the female cases, and the patients aged between 40 and 50 years old were dominant. The COVID-19 was highly prevalent in Xi'an, Ankang and Hanzhong. The SEIAR model showed that the basic regeneration index(R0) of the epidemic in Shaanxi Province was about 2.95, concluding that the beginning of Feb. 2020 was the peak period of outbreak of COVID-19 in Shaanxi Province. CONCLUSION: The COVID-19 epidemic in Shaanxi province shows a fast spreading trend. The theoretical number of confirmed cases that is predicted based on the SEIAR model can provide basis for prevention and control of the COVID-19 epidemic and curb the spread of the epidemic.

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