Yongchen Zhang

Bio: Yongchen Zhang is an academic researcher from Nanjing University of Chinese Medicine. The author has contributed to research in topics: Virology & Virus. The author has an hindex of 2, co-authored 4 publications receiving 1092 citations.

Development and Clinical Application of A Rapid IgM-IgG Combined Antibody Test for SARS-CoV-2 Infection Diagnosis

Abstract: The outbreak of the novel coronavirus disease (COVID-19) quickly spread all over China and to more than 20 other countries. Although the virus (severe acute respiratory syndrome coronavirus [SARS-Cov-2]) nucleic acid real-time polymerase chain reaction (PCR) test has become the standard method for diagnosis of SARS-CoV-2 infection, these real-time PCR test kits have many limitations. In addition, high false-negative rates were reported. There is an urgent need for an accurate and rapid test method to quickly identify a large number of infected patients and asymptomatic carriers to prevent virus transmission and assure timely treatment of patients. We have developed a rapid and simple point-of-care lateral flow immunoassay that can detect immunoglobulin M (IgM) and IgG antibodies simultaneously against SARS-CoV-2 virus in human blood within 15 minutes which can detect patients at different infection stages. With this test kit, we carried out clinical studies to validate its clinical efficacy uses. The clinical detection sensitivity and specificity of this test were measured using blood samples collected from 397 PCR confirmed COVID-19 patients and 128 negative patients at eight different clinical sites. The overall testing sensitivity was 88.66% and specificity was 90.63%. In addition, we evaluated clinical diagnosis results obtained from different types of venous and fingerstick blood samples. The results indicated great detection consistency among samples from fingerstick blood, serum and plasma of venous blood. The IgM-IgG combined assay has better utility and sensitivity compared with a single IgM or IgG test. It can be used for the rapid screening of SARS-CoV-2 carriers, symptomatic or asymptomatic, in hospitals, clinics, and test laboratories.

Characterization of a big family cluster infection associated with SARS-Cov-2 in Nanjing district

Abstract: Background: Outbreak of COVID-19 has brought catastrophe to huge numbers of families. However, even though numerous tragedies occurred, there were few reports about family cluster infection in the academic journals. Methods: The electronic medical records of 10 COVID-19 patients in a big family were retrospectively reviewed and analyzed.Results: These 10 patients, 4 males and 6 females, were infected through two successive family feasts during Spring Festival. The infection source was a family member at asymptomatic state, who lived in Hubei but travelled to Nanjing. The median age of these 10 patients was 61.5, with the oldest 95 and youngest 38. The incubation period varied from 3 to 17 days, with the median of 5.5. Of them, 2 patients were asymptomatic. The most common symptoms at onset were fever (6/10) and dry cough (6/10). All of them displayed lesions on the chest CT. 40% of them had leukopenia, neutropenia and lymphopenia. After anti-virus treatment, all the patients significantly improved and were discharged. Conclusions: SARS-Cov-2 was highly contagious and so crafty that a varied incubation period did exist. Part of patients might be asymptomatic, which was the potential source of transmission. More measures for protection or quarantine should be taken at home if family member had travel history nearby the epidemic area.

Epidemiological and clinical characteristics of COVID-19 patients in Nanjing

Abstract: Background: Since December 2019, the outbreak of COVID-19 has spread quickly and thumped many countries and regions. The epidemic of central China was under the spotlight and attracted much more attentions. However, there are few reports describing COVID-19 patients in the regions outside of Wuhan, which are undergoing the change from sporadic imported cases to community-acquired transmission.Methods: The electronic medical records of 74 laboratory-confirmed patients of COVID-19 were retrospectively reviewed and analyzed. Their epidemiological, demographic, clinical and radiological characteristics were systematically summarized. The difference between severe patients and non-severe patients were also analyzed statistically.Results: The 74 COVID-19 patients were composed of 4 (5.4%) mild patients, 56 (75.7%) common patients, 13 (17.6%) severe patients and 1 (1.4%) critical patient. 43 were male, and 31 were female, with the average age 48.1±17.5. No significant difference of susceptibility was observed between genders, and almost people with all age were susceptible to SARS-CoV-2 infection. Before Jan 26, only imported sporadic cases were observed. However, from that day onward, family cluster infection cases increased dramatically, up to 70.3% (52/74), which were mainly from 15 family. The incubation period spanned from 0 to 19 days, with the median 5, and 81.4% had symptom onset within 7 days. At admission, 31.1% of patients had underlying diseases and the most common underlying diseases were hypertension (13.5%) and diabetes (5.4%). The most common symptoms were fever (90.5%), cough (75.7%), fatigue (36.5%) and chest distress (32.4%). 36.5% and 16.2% of patients had leukopenia and lymphocytopenia. 43.2% of patients had increased C reactive protein (CRP), and 40.5% had higher erythrocyte sedimentation rate (ESR) and 21.6% had higher calcitonin. 74.3% of patients had obvious lesions in both lung lobes and 56.8% of lesions manifested as ground glass opacity. Compared with non-severe group, the severe/critical group were significantly older and had more underlying diseases. After treatment, all patients improved and were discharged. No medical professional infection and death case were reported.Conclusion: The epidemic of COVID-19 in Nanjing were mainly caused by family cluster infection. The entire prevalence and illness were much milder than those of Wuhan. The disease of COVID-19 could be controlled and cured.

Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study

Abstract: Summary Background Since December, 2019, Wuhan, China, has experienced an outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemiological and clinical characteristics of patients with COVID-19 have been reported but risk factors for mortality and a detailed clinical course of illness, including viral shedding, have not been well described. Methods In this retrospective, multicentre cohort study, we included all adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China) who had been discharged or had died by Jan 31, 2020. Demographic, clinical, treatment, and laboratory data, including serial samples for viral RNA detection, were extracted from electronic medical records and compared between survivors and non-survivors. We used univariable and multivariable logistic regression methods to explore the risk factors associated with in-hospital death. Findings 191 patients (135 from Jinyintan Hospital and 56 from Wuhan Pulmonary Hospital) were included in this study, of whom 137 were discharged and 54 died in hospital. 91 (48%) patients had a comorbidity, with hypertension being the most common (58 [30%] patients), followed by diabetes (36 [19%] patients) and coronary heart disease (15 [8%] patients). Multivariable regression showed increasing odds of in-hospital death associated with older age (odds ratio 1·10, 95% CI 1·03–1·17, per year increase; p=0·0043), higher Sequential Organ Failure Assessment (SOFA) score (5·65, 2·61–12·23; p Interpretation The potential risk factors of older age, high SOFA score, and d-dimer greater than 1 μg/mL could help clinicians to identify patients with poor prognosis at an early stage. Prolonged viral shedding provides the rationale for a strategy of isolation of infected patients and optimal antiviral interventions in the future. Funding Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences; National Science Grant for Distinguished Young Scholars; National Key Research and Development Program of China; The Beijing Science and Technology Project; and Major Projects of National Science and Technology on New Drug Creation and Development.

Modelling the COVID-19 epidemic and implementation of population-wide interventions in Italy.

Abstract: In Italy, 128,948 confirmed cases and 15,887 deaths of people who tested positive for SARS-CoV-2 were registered as of 5 April 2020. Ending the global SARS-CoV-2 pandemic requires implementation of multiple population-wide strategies, including social distancing, testing and contact tracing. We propose a new model that predicts the course of the epidemic to help plan an effective control strategy. The model considers eight stages of infection: susceptible (S), infected (I), diagnosed (D), ailing (A), recognized (R), threatened (T), healed (H) and extinct (E), collectively termed SIDARTHE. Our SIDARTHE model discriminates between infected individuals depending on whether they have been diagnosed and on the severity of their symptoms. The distinction between diagnosed and non-diagnosed individuals is important because the former are typically isolated and hence less likely to spread the infection. This delineation also helps to explain misperceptions of the case fatality rate and of the epidemic spread. We compare simulation results with real data on the COVID-19 epidemic in Italy, and we model possible scenarios of implementation of countermeasures. Our results demonstrate that restrictive social-distancing measures will need to be combined with widespread testing and contact tracing to end the ongoing COVID-19 pandemic.

Laboratory Diagnosis of COVID-19: Current Issues and Challenges.

Abstract: The COVID-19 outbreak has had a major impact on clinical microbiology laboratories in the past several months. This commentary covers current issues and challenges for the laboratory diagnosis of infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In the preanalytical stage, collecting the proper respiratory tract specimen at the right time from the right anatomic site is essential for a prompt and accurate molecular diagnosis of COVID-19. Appropriate measures are required to keep laboratory staff safe while producing reliable test results. In the analytic stage, real-time reverse transcription-PCR (RT-PCR) assays remain the molecular test of choice for the etiologic diagnosis of SARS-CoV-2 infection while antibody-based techniques are being introduced as supplemental tools. In the postanalytical stage, testing results should be carefully interpreted using both molecular and serological findings. Finally, random-access, integrated devices available at the point of care with scalable capacities will facilitate the rapid and accurate diagnosis and monitoring of SARS-CoV-2 infections and greatly assist in the control of this outbreak.