Aerodynamic performance of a ventilation system for droplet control by coughing in a hospital isolation ward.

Over 766 million people have been infected by coronavirus disease 2019 (COVID-19) in the past 3 years, resulting in 7 million deaths. The virus is primarily transmitted through droplets or aerosols produced by coughing, sneezing, and talking. A full-scale isolation ward in Wuhan Pulmonary Hospital is modeled in this work, and water droplet diffusion is simulated using computational fluid dynamics (CFD). In an isolation ward, a local exhaust ventilation system is intended to avoid cross-infection. The existence of a local exhaust system increases turbulent movement, leading to a complete breakup of the droplet cluster and improved droplet dispersion inside the ward. When the outlet negative pressure is 4.5 Pa, the number of moving droplets in the ward decreases by approximately 30% compared to the original ward. The local exhaust system could minimize the number of droplets evaporated in the ward; however, the formation of aerosols cannot be avoided. Furthermore, 60.83%, 62.04%, 61.03%, 60.22%, 62.97%, and 61.52% of droplets produced through coughing reached patients in six different scenarios. However, the local exhaust ventilation system has no apparent influence on the control of surface contamination. In this study, several suggestions with regards to the optimization of ventilation in wards and scientific evidence are provided to ensure the air quality of hospital isolation wards.

Nucleic acid detection of fecal samples from confirmed cases of COVID-19

To investigate the status of viral infection in the feces of confirmed COVID-19, cases fecal samples or anal swabs from 36 confirmed cases were collected, 2019-nCoV was detected by real-time fluorescence RT-PCR, and the infection rates of the cases were compared by statistical analysis software SPSS 19.0. Among the 36 samples, 20 (55.56%) were positive for 2019-nCoV. The positive rate of critical cases (2/3) and severe cases(6/9) were both 66.67%, the positive rate of common pneumonia was 62.50% (10/16), and the positive rate of mild pneumonia was 25.00% (2/8). The 36 confirmed COVID-19 cases included 22 males and 14 females, with a detection rate of 54.55% and 57.14%, respectively. The age distribution range of the cases was ranging between 17 and 86 years old, with an average age of 48.75 years. Among the 36 samples, 2 positive specimens in 5 anal swab specimens and 18 positive specimens in 31 fecal specimens were detected. There were no statistically significant differences in the positive detection rates among clinical types, genders, ages and specimen types, respectively. From these results, we deduced that fecal samples of confirmed COVID-19 cases contained 2019-nCoV, which can cause infection through potential fecal-oral transmission and be significant for clinical treatment and epidemiological study.

Improvement of Sensitivity of Pooling Strategies for COVID-19.

Group testing (or pool testing), for example, Dorfman's method or grid method, has been validated for COVID-19 RT-PCR tests and implemented widely by most laboratories in many countries. These methods take advantages since they reduce resources, time, and overall costs required for a large number of samples. However, these methods could have more false negative cases and lower sensitivity. In order to maintain both accuracy and efficiency for different prevalence, we provide a novel pooling strategy based on the grid method with an extra pool set and an optimized rule inspired by the idea of error-correcting codes. The mathematical analysis shows that (i) the proposed method has the best sensitivity among all the methods we compared, if the false negative rate (FNR) of an individual test is in the range [1%, 20%] and the FNR of a pool test is closed to that of an individual test, and (ii) the proposed method is efficient when the prevalence is below 10%. Numerical simulations are also performed to confirm the theoretical derivations. In summary, the proposed method is shown to be felicitous under the above conditions in the epidemic.

Long non-coding RNAs: Promising new targets in pulmonary fibrosis.

Pulmonary fibrosis is characterized by progressive and irreversible scarring in the lungs with poor prognosis and treatment. It is caused by various factors, including environmental and occupational exposures, and some rheumatic immune diseases. Even the rapid global spread of the COVID-19 pandemic can also cause pulmonary fibrosis with a high probability. Functions attributed to long non-coding RNAs (lncRNAs) make them highly attractive diagnostic and therapeutic targets in fibroproliferative diseases. Therefore, an understanding of the specific mechanisms by which lncRNAs regulate pulmonary fibrotic pathogenesis is urgently needed to identify new possibilities for therapy. In this review, we focus on the molecular mechanisms and implications of lncRNAs targeted protein-coding and non-coding genes during pulmonary fibrogenesis, and systematically analyze the communication of lncRNAs with various types of RNAs, including microRNA, circular RNA and mRNA. Finally, we propose the potential approach of lncRNA-based diagnosis and therapy for pulmonary fibrosis. We hope that understanding these interactions between protein-coding and non-coding genes will contribute to the development of lncRNA-based clinical applications for pulmonary fibrosis.

Gastrointestinal Symptoms Onset in COVID-19 Patients in Wuhan, China.

BACKGROUND: Early detection is critical in limiting the spread of 2019 novel coronavirus (COVID-19). Although previous data revealed characteristics of GI symptoms in COVID-19, for patients with only GI symptoms onset, their diagnostic process and potential transmission risk are still unclear. METHODS: We retrospectively reviewed 205 COVID-19 cases from January 16 to March 30, 2020, in Renmin Hospital of Wuhan University. All patients were confirmed by virus nuclei acid tests. The clinical features and laboratory and chest tomographic (CT) data were recorded and analyzed. RESULTS: A total of 171 patients with classic symptoms (group A) and 34 patients with only GI symptoms (group B) were included. In patients with classical COVID-19 symptoms, GI symptoms occurred more frequently in severe cases compared to non-severe cases (20/43 vs. 91/128, respectively, p < 0.05). In group B, 91.2% (31/34) patients were non-severe, while 73.5% (25/34) patients had obvious infiltrates in their first CT scans. Compared to group A, group B patients had a prolonged time to clinic services (5.0 days vs. 2.6 days, p < 0.01) and a longer time to a positive viral swab normalized to the time of admission (6.9 days vs. 3.3 days, respectively, p < 0.01). Two patients in group B had family clusters of SARS-CoV-2 infection. CONCLUSION: Patients with only GI symptoms of COVID-19 may take a longer time to present to healthcare services and receive a confirmed diagnosis. In areas where infection is rampant, physicians must remain vigilant of patients presenting with acute gastrointestinal symptoms and should do appropriate personal protective equipment.

Isolation and genome sequence analyses of 2019-nCoV from COVID-19 patients in Fujian Province, China

To explore genomic characteriation of 2019-nCoV, throat swab specimens from COVID-19 patients were inoculated on Vero-E6 cells. Six days post-inoculation, supernatants of cell cultures were collected, tested, and sequenced on the Ion Torrent S5 Next-Generation Sequencing system. Two strains viruses were isolated from 12 specimens (eight of them were positive in ORF1ab gene and N gene, one of them was positive in N gene and three of them were negative in ORF1ab gene and N gene), as confirmed by online BLAST search at NCBI website. Genetic similarity of more than 99.9% were observed, from genomic level to structure genes including E, M, N and S genes, between the 2 isolates and the 2019-nCoV reference strain Wuhan-Hu-1 that isolated from Wuhan, Hubei province. Therefore, these results indicated that 2019-nCoV isolates in Fujian province have not mutated significantly yet so far.