Neural alterations of Omicron infection comorbid with insomnia in Chinese: Insight from surface-based morphometry and bibliometric analysis (preprint)

Growing evidence suggests that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect the central nervous system (CNS), and insomnia-related acute and long-term CNS sequelae may be suffered by infected patients. Nevertheless, as a common sub-typic strain of SARS-CoV-2, it is currently unknown the impacts of Omicron comorbid with insomnia on brain cortex. The purpose of this study was to mine the neural markers involving cortical grey matter volume (GMV), thickness, and surface area within Omicron individuals either with or without insomnia. Additionally, correlations between these morphological metrics and neuropsychiatric assessments were analyzed. 234 participants were recruited from a prospective cross-sectional study cohort during the Omicron pandemic (December 2022-May 2023) at the Second Xiangya Hospital (China). We further divided participants into healthy controls (HCs), Omicron infection with insomnia group (Omicron_insomnia group), and Omicron infection without insomnia group (Omicron_non_insomnia group). Based on T1-weighted MPRAGE image, cortical thickness, surface area, and GMV were compared via surface-based morphometry (SBM) analysis, and significant morphological metrics were then correlated with neuropsychiatric manifestations. Our findings revealed altered cortical morphology in Omicron individuals. Morphological changes in the temporal, frontal, cingulate, transverse collateral, and lingual gyrus were independent from insomnia comorbidity. The decreased cortical thickness in superior temporal gyrus (STG) was a specific feature for Omicron infection comorbid with insomnia. Then, we discovered greater morphological size indicating neuropsychiatric improvement. This study explores the neural mechanisms underlying Omicron infection comorbid with insomnia, which will help to promote improvement in post-Omicron neuropsychiatric prognosis and clinical management.

Comparison of foodborne disease outbreaks data in China and the United States from 2011 to 2017 and its inspiration for the construction of monitoring system in China

The history of the establishment of foodborne disease outbreak monitoring system in the United States was introduced and the surveillance data of foodborne disease outbreaks in the United States from 2011 to 2017 were analyzed and compared with that in China. It was found that there were obvious differences in the characteristics of surveillance data of foodborne disease outbreaks between China and the United States in the same period, and microbial pathogenic factors were the main cause of foodborne disease outbreaks. Facing the challenges of global trade integration and post epidemic era of COVID-19,China's foodborne disease outbreak monitoring system should accelerate the use of new technologies to improve the ability of identification and early warning, and foodborne disease outbreak data results should further play the technical support role in the formulation of relevant food safety management measures in China.

The study of psychological traits among Chinese college students during the COVID-19 campus lockdown

To investigate the prevalence of interpersonal sensitivity, anxiety, depression symptoms and associated risk factors among a large-scale sample of college students in China during the COVID-19 campus lockdown. The survey was conducted among undergraduate students at a university in eastern part of China in April 2022. The Chi-square test was used to compare the different variable groups and multivariable analysis was performed for the risk factors associated with interpersonal sensitivity, anxiety, and depression symptoms. A total of 12,922 college students were included, with an average age of (20.96 ± 1.66) years. The prevalence of interpersonal sensitivity, anxiety and depression symptoms in this study was 58.1, 22.7, and 46.8%, respectively. Male (OR = 1.16, p < 0.001), 22–23 years (OR = 1.40, p < 0.001), freshman (OR = 1.35, p = 0.002), and non-only child (OR = 1.15, p < 0.001) were positively associated with interpersonal sensitivity. Male (OR = 1.20, p < 0.001), sophomores (OR = 1.27, p = 0.020) and seniors (OR = 1.20, p = 0.027) were positively associated with anxiety symptoms. Compared with female students, male students (OR = 0.89, p < 0.001) were less likely to have depression symptoms. 22–23 years (OR = 1.37, p < 0.001), sophomores (OR = 1.26, p = 0.009) and non-only child (OR = 1.11, p = 0.009) were positively associated with depression symptoms. In addition, college students aged 18–21 years, learning status, skipping breakfast, roommate relationship and sleep quality were associated with interpersonal sensitivity, anxiety and depression symptoms (all p < 0.05). The findings of this study suggest a high prevalence of interpersonal sensitivity, anxiety and depression symptoms among Chinese college students during the COVID-19 campus lockdown. Younger ages, low grades, poor dormitory relationship, negative learning status, skipping breakfast and poor sleep quality were the risk factors for college students’ mental health, which should be concerned by the relevant departments of school during the campus lockdown.

Automatic CT Whole-Lung Segmentation in Radiomics Discrimination: Methodology and Application in Pneumonia Diagnosis and Distinguishment

Radiomics based on lesion segmentation has been widely accepted for disease diagnosis;however, it is difficult to precisely determine the boundary for pneumonia due to its diffuse characteristics. In this study, we aimed to propose an automatic radiomics method using whole-lung segmentation in pneumonia discrimination and assist clinical practitioners in fast and accurate diagnosis. In the discovery set, data from 151 participants diagnosed with type A or B influenza virus pneumonia, 63 diagnosed with coronavirus disease 2019 (COVID-19) and 50 healthy participants were collected. The three groups of data were compared in pairs. A total of 117 radiomics features were extracted from whole-lung images segmented by a four-layer U-net. We then utilized a logistic regression model to train the model and used the area under the receiver operating characteristic curve (AUC) to assess its performance. The L1 regularization term was used in feature selection, and 10-fold cross-validation was used to tune the hyperparameters. Fourteen radiomics features were selected to classify influenza pneumonia and health, and the AUC was 0.957 (95% confidential interval (CI): 0.939, 0.976) in the training set and 0.914 (95% CI: 0.866, 0.963) in the testing set. Eighteen features were selected for COVID-19 and health, and the AUC was 0.949 (95% CI: 0.926, 0.973)in the training set and 0.911 (95% CI: 0.859, 0.963) in the testing set. Twenty-eight features were selected for influenza virus pneumonia and COVID-19, and the AUC was 0.895 (95% CI: 0.870, 0.920) in the training set and 0.839 (95% CI: 0.791, 0.887) in the testing set. The results show that the automatic radiomics model based on whole lung segmentation is effective in distinguishing influenza virus pneumonia, COVID-19 and health, and may assist in the diagnosis of influenza virus pneumonia and COVID-19.

Cell culture model system utilizing engineered A549 cells to express high levels of ACE2 and TMPRSS2 for investigating SARS-CoV-2 infection and antivirals (preprint)

Novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose an imminent global threat since its initial outbreak in December 2019. A simple in vitro model system using cell lines highly susceptible to SARS-CoV-2 infection are critical to facilitate the study of the virus cycle and to discover effective antivirals against the virus. Human lung alveolar A549 cells are regarded as a useful and valuable model for respiratory virus infection. However, SARS-CoV-2 uses the ACE2 as receptor for viral entry and the TMPRSS2 to prime the Spike protein, both of which are negligibly expressed in A549 cells. Here, we report the generation of a robust human lung epithelial cell-based model by transducing ACE2 and TMPRSS2 into A549 cells and show that the ACE2 enriched A549ACE2/TMPRSS2 cells (ACE2plus) and its single-cell-derived subclone (ACE2plusC3) are highly susceptible to SARS-CoV-2 infection. These engineered ACE2plus showed higher ACE2 and TMPRSS2 mRNA expression levels than currently used Calu3 and commercial A549ACE2/TMPRSS2 cells. ACE2 and TMPRSS2 proteins were also highly and ubiquitously expressed in ACE2plusC3 cells. Additionally, antiviral drugs like Camostat mesylate, EIDD-1931, and Remdesivir strongly inhibited SARS-CoV-2 replication. Notably, multinucleated syncytia, a clinical feature commonly observed in severe COVID-19 patients was induced in ACE2plusC3 cells either by virus infection or by overexpressing the Spike proteins of different variants of SARS-CoV-2. Syncytial process was effectively blocked by the furin protease inhibitor, Decanoyl-RVKR-CMK. Taken together, we have developed a robust human A549 lung epithelial cell-based model that can be applied to probe SARS-CoV-2 replication and to facilitate the discovery of SARS-CoV-2 inhibitors.

Design characteristics on the indoor and outdoor environments of the COVID-19 emergency hospital

According to the discussion of the design method and operational effect for Wuhan Huoshenshan Hospital, this paper summarized the design control points of indoor and outdoor environment of COVID-19 emergency hospital. Based on the design of Wuhan Huoshenshan Hospital, this paper analyzed and discussed the site design, building layout, three-zones and two-passages, the design scheme of the ventilation and air conditioning system for negative pressure ward and negative pressure isolation ward, air distribution, as well as some other key designs for COVID-19 emergency hospital. The design points were summarized and refined. The design methods and technology requirements of the COVID-19 emergency hospital were provided in this study, such as ventilation and air conditioning system setting, ventilation quantity of wards, pressure gradient control measures among different areas, upper and lower air distribution, filter setting mode and distance of air inlet and outlet, which could benefit to provide references for the design of similar projects in the future.

Differentiation between COVID‐19 and bacterial pneumonia using radiomics of chest computed tomography and clinical features

To develop and validate an effective model for distinguishing COVID‐19 from bacterial pneumonia. In the training group and internal validation group, all patients were randomly divided into a training group (n = 245) and a validation group (n = 105). The whole lung lesion on chest computed tomography (CT) was drawn as the region of interest (ROI) for each patient. Both feature selection and model construction were first performed in the training set and then further tested in the validation set with the same thresholds. Additional tests were conducted on an external multicentre cohort with 105 subjects. The diagnostic model of LightGBM showed the best performance, achieving a sensitivity of 0.941, specificity of 0.981, accuracy of 0.962 on the validation dataset. In this study, we established a differential model to distinguish between COVID‐19 and bacterial pneumonia based on chest CT radiomics and clinical indexes.

Comprehensive Profiling and Characterization of The Absorbed Components and Metabolites in Mice Serum and Tissues Following Oral Administration of Qingfei Paidu Decoction by UHPLC-Q-Exactive-Orbitrap HRMS (preprint)

Background: Qingfei Paidu decoction (QFPDD) is a Chinese medicine compound formula recommended for combating corona virus disease 2019 (COVID-19) by National Health Commission of the People's Republic of China. This study aims to identify the main constituents in QFPDD and the absorbed components (including prototypes and metabolites) in serum and tissues after oral administration of QFPDD to mice.Methods: A practical and sensitive method of UHPLC-Q-Exactive-Orbitrap HRMS was developed to identify the chemical constituents in QFPDD and the absorbed prototypes as well as the metabolites in mice serum and tissues following oral administration of QFPDD.Results: A total of 405 chemicals, including 40 kinds of alkaloids, 162 kinds of flavonoids, 44 kinds of organic acids, 71 kinds of triterpene saponins and 88 kinds of other compounds in the water extract of QFPDD were tentatively identified via comparison with the retention times and MS/MS spectra of the standards or refereed by literature. With the help of the standards and in vitro metabolites, 195 chemical components (including 104 prototypes and 91 metabolites) were identified in mice serum after oral administration of QFPDD. In addition, 165, 177, 112, 120, 44, 53 constituents were identified in the lung, liver, heart, kidney, brain, and spleen of QFPDD-treated mice, respectively.Conclusions: An UHPLC-Q-Orbitrap HRMS based method was established for chemical profiling the constituents in QFPDD, while the absorbed prototypes and metabolites occurring in mice serum and tissues were investigated following oral administration of QFPDD. These findings provided key information and guidance for further investigation on the pharmacologically active substances and clinical applications of QFPDD.

Effects of case- and population-based COVID-19 interventions in Taiwan (preprint)

In the first wave of the COVID-19 pandemic, broad usage of non-pharmaceutical interventions played a crucial role in controlling epidemics. However, the substantial economic and societal costs of continuous use of border controls, travel restrictions, and physical distancing measures suggest that these measures may not be sustainable and that policymakers have to seek strategies to lift the restrictions. Taiwan was one of the few countries that demonstrated initial success in eliminating the COVID-19 outbreak without strict lockdown or school closure. To understand the key contributors to the successful control, we applied a stochastic branching model to empirical case data to evaluate and compare the effectiveness of more targeted case-based (including contact tracing and quarantine) and less targeted population-based interventions (including social distancing and face mask use) in Taiwan. We found that case-based interventions alone would not be sufficient to contain the epidemic, even in a setting where a highly efficient contact tracing program was in place. The voluntary population-based interventions have reduced the reproduction numbers by more than 60% and have likely played a critical role at the early stage of the outbreak. Our analysis of Taiwan's success highlights that coordinated efforts from both the government and the citizens are indispensable in the fight against COVID-19 pandemic.

Asymptomatic “Exposers” and “Infectors” are Sources of Infection by SARS-CoV-2: Analysis based on Family Clustering (preprint)

Background: Previous studies have documented the clinical characteristics of patients with Coronavirus disease 2019(COVID-19) and presented evidence of person-to-person transmission. Limited data are available for patients with asymptomatic infections. Some asymptomatic carriers, whom we characterize as “exposers” or “infectors”, may be responsible for family clustering of COVID-19.Methods: A questionnaire survey and follow-up survey based on media reports were used to assess familial clustering of SARS-CoV-2 infection induced by asymptomatic exposers/infectors. Individual data were collected for all members of each tracked family. A transmission map was then drawn for each family.Results: Our study of 5 families indicated that individuals with no obvious symptoms of COVID-19, regardless of the PCR results, transmitted the virus to other family members who were community contained at home and had no contact with other infected individuals. There was one death case in Family No.3. Conclusion: Asymptomatic exposers/infectors of SARS-CoV-2 were all middle-aged (average age: 44.4 ± 14.9 years) who had no symptoms but had the ability to disseminate the virus. Medical staff participating in treatment of COVID-19 cases all had a high risk of infection, they should be quarantined so as to protect their families. The morbidity and mortality of Case 3.2 remind us that although these asymptomatic infected people have no symptoms, they are also infectious. It is not ruled out that the subsequent infected people are seriously ill or even die. Therefore, we should not take it lightly.

An online tool for predicting the prognosis of cancer patients with SARS-CoV-2 infection: a multi-center study (preprint)

Purpose: During the coronavirus disease 2019 (COVID-19) pandemic, oncologists face new challenges and they need to adjust their cancer management strategies as soon as possible to reduce the risk of SARS-CoV-2 infection and tumor recurrence. However, data on cancer patients with SARS-CoV-2 infection remains scarce. Methods: We performed a retrospective study of 223 cancer patients with SARS-CoV-2 from 26 hospitals in Hubei, China. An individualized nomogram was constructed based on multivariable Cox analysis. Considering the convenience of the nomogram application, an online tool was also created by shiny app. C-index, calibration curves and decision curve analysis (DCA) were performed to verify the prediction performance and clinical application of the nomogram.Results: Among cancer patients with SARS-CoV-2, there were significant differences in clinical characteristics between survivors and non-survivors, and lung cancer patients had similar short-time survival with other cancer patients. Male, dyspnea, elevated PCT, increased heart rate, elevated D-dimers, decreased platelets and so on were risk factors for these patients. Furthermore, good prediction performance of the online tool (dynamic nomogram: https://covid-19-prediction-tool.shinyapps.io/DynNomapp/). was also fully demonstrated with the C-index of 0.841 (95% CI: 0.782 - 0.900) in the development cohort and 0.780 (95% CI: 0.678-0.882) in the validation cohort. Conclusion: Overall, cancer patients with SARS-CoV-2 had unique clinical features, and the established online tool could guide clinicians to predict the prognosis of patients and to develop more rational treatment strategies for cancer patients during the COVID-19 epidemic.

How can traditional Chinese medicine contribute to the therapeutic approach in coronavirus disease 2019 (COVID-19)? A review of the registered clinical trials (preprint)

Background: Since the outbreak of coronavirus disease 2019 (COVID-19) in January 2020, Traditional Chinese Medicine (TCM) has been fully and deeply involved in the treatment of COVID-19 in China. An increasing number of clinical trials has been registered to evaluate the effects of TCM in the prevention and therapeutic management of COVID-19.Objective: This study aims to review the existing TCM registered trials, identify promising and available TCM therapies, in order to provide reference for the global management of COVID-19. Methods: All clinical trials on TCM for COVID-19 registered in eight registry platforms worldwide were searched up to May 14, 2020. The data of registration trend, design, objective, interventions, current status, and relevant information were reviewed and summarized. Supportive information on the progress, results and potential value of the included registered trials were searched and reviewed from databases and official websites. Results: 161 TCM trials registered in three registries from January 26 to May 14 were included. 94 (58.4%) were randomized controlled trials, followed by controlled clinical trials (25, 15.5%), single-arm clinical studies (18, 11.2%) and others (24, 14.9%). 114 trials (70.8%) assessed therapeutic effects; while the remaining were for prevention, rehabilitation, and TCM syndrome epidemiology. The three most evaluated TCM interventions were Chinese herbal medicine (CHM) in the preparation forms of formulae decoction/granule (41.7%), Chinese patent medicine (24.8%) and Chinese herbal-derived injections (8.1%). The common outcomes in therapeutic trials were symptoms and signs (65.8%), time to viral clearance on PCR (50.9%), and improvement in CT images (43.9%). 78 trials (48.4%) had started recruiting and six trials (3.7%) had completed recruiting. Among the TCM interventions identified from the registered trials, the following are worthy of attention and may have the potential feasibility of being evaluated and then used worldwide due to their rigorous design, previous evidence and availability: for prevention in high-risk populations or suspected cases, moxibustion, Huoxiang Zhengqi pill and Jinye Baidu granule could be considered; for treatment, Qingfei Paidu decoction or granules in mild, moderate and severe cases, Huashi Baidu decoction, Lianhua Qingwen caplsule, Toujie Quwen granule and Xiyanping injection in mild and moderate cases, and Xuebijing injection in severe cases could be considered. For rehabilitation of cured patients, the effect of Tai Chi and Liuzijue on the patients’ lung function and quality of life deserves attention.Conclusion: A series of promising potentially effective TCM interventions including CHM formulae, Chinese patent medicines, herbal-derived injections and non-drug therapies have been identified in clinical practice and are being evaluated by registered clinical trials. Available and applicable interventions within relevant trials are worthy of worldwide attention and application, in order to contribute to the global management of COVID-19 epidemic.

Development and validation of chest CT-based imaging biomarkers for early stage COVID-19 screening (preprint)

Coronavirus Disease 2019 (COVID-19) is currently a global pandemic, and the early screening of COVID-19 is one of the key factors for COVID-19 control and treatment. Here, we developed and validated chest CT-based imaging biomarkers for COVID-19 patient screening. We identified the vasculature-like signals from CT images and found that, compared to healthy and community acquired pneumonia (CAP) patients, the COVID-19 patients revealed significantly higher abundance of these signals. Furthermore, unsupervised feature learning leads to the discovery of clinical-relevant imaging biomarkers from the vasculature-like signals for accurate and sensitive COVID-19 screening that has been double-blindly validated in an independent hospital (sensitivity: 0.941, specificity: 0.904, AUC: 0.952). Our findings could open a new avenue to assist screening of COVID-19 patients.

A Survey of Characteristics and Potential Contribution of Registered Studies for 2019 novel coronavirus disease (COVID-19) (preprint)

Background The World Health Organization characterized the 2019 novel coronavirus disease (COVID-19) as a pandemic on March 11. Many clinical trials on COVID-19 have been registered, and we aim to review the characteristics of the trials and provide guidance for future trials to avoid duplicated effort.Methods All the studies on COVID-19 registered before Mar 3, 2020 on eight registry platforms worldwide were searched and the data of design, participants, interventions, and outcomes were extracted and analyzed. The most promising trials were screened based on study design, rationale, and resource availability.Results 393 studies registered were identified until Mar 3 2020 and 380 (96.7%) studies were from mainland China, while 3 in Japan, 3 in France, 2 in the US, and 3 were international collaborative studies. 363 studies (92.4%) recruited participants from hospitals and 266 studies (67.7%) aimed at therapeutic effect, others were for prevention, diagnosis, prognosis, etc. 202 studies (51.4%) were randomized controlled trials (RCTs). The average sample size was 1061 and ranged from 8 to 150,000 per study. 177 out of 266 therapeutic studies (66.5% ) tested Western medicines including antiviral drugs (17.7%), stem cell and cord blood therapy (10.2%), chloroquine and derivatives (8.3%), 16 (6.0%) on Chinese medicines, and 73 (27.4%) on integrated therapy of Western and Chinese medicines. 14 Chinese medicines had its clear rationale for evaluation of therapeutic effects. 31 studies among 266 therapeutic studies (11.7%) used mortality as primary outcome, while the most designed secondary outcomes were symptoms and signs (47.0%). 106 studies (27.0%) were funded by the government, and 268 (68.2%) demonstrated ethical approval. 45.5% studies (179 out of 266) had not started recruiting till Mar 3. Eight RCTs were evaluated as the most promising trials.Conclusions Majority of the studies focused on assessing therapeutics for COVID-19 but inappropriate outcome setting, delayed recruitment and insufficient numbers of new cases in China implied many studies may fail to complete. Strategies and protocols of the studies with robust and rapid data sharing from international collaboration are warranted for emergency public health events, helping to accelerate priority setting for timely evidence-based decision-making.

Acceptance and preference for COVID-19 vaccination in health-care workers (HCWs) (preprint)

The objective of the present study is to reveal the acceptance and preference for the 2019 novel coronavirus disease (COVID-19) vaccination in health-care workers (HCWs). We performed an internet-based, region-stratified survey among 352 HCWs and 189 individuals in the general population enrolled on March 17th and 18th 2020 from 26 Chinese provinces. The HCWs developed a more in-depth understanding of SARS-Coronavirus-2 infection and showed a higher tolerance to the future vaccination than the general population. 76.4% of HCWs (vs. 72.5% in the general) showed their willingness to receive vaccination. Potential benefits from COVID-19 outbreak such as seeking influenza (65.3%) or pneumonia (55.7%) vaccination can be gained in HCWs. To estimate the relative effects of attributes influencing vaccination choice in the discrete choice experiment, 7 attributes (3 disease-relevant, 3 vaccine-relevant, and 1 of social acceptance) were identified as key determinants. Among them, disease trend (odds ratio, OR: 4.367 (95%CI, 3.721-5.126) for seasonal epidemic, OR: 3.069 (2.612-3.605) for persistent epidemic, with reference to disappearance in summer), social contacts decisions (0.398: 0.339-0.467 for refusal, 0.414: 0.353-0.487 for neutral, with reference to acceptance) and high possibility of being infected (2.076: 1.776-2.425 for infection probability of 30%+ ) were significantly associated with increased probability of choosing vaccination in the HCWs. In contrast, for the general population, vaccine safety and social contacts decisions were the most important predictors. For COVID-19 vaccination, education in HCWs should be taken as a priority, and further benefits of its recommendation to the general public will also be anticipated.

Modes of contact and risk of transmission in COVID-19 among close contacts (preprint)

Background Rapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Guangzhou and elsewhere in China. Modes of contact and risk of transmission among close contacts have not been well estimated. Methods We included 4950 closes contacts from Guangzhou, and extracted data including modes of contact, laboratory testing, clinical characteristics of confirmed cases and source cases. We used logistic regression analysis to explore the risk factors associated with infection of close contacts. Results Among 4950 closes contacts, the median age was 38.0 years, and males accounted for 50.2% (2484). During quarantine period, 129 cases (2.6%) were diagnosed, with 8 asymptomatic (6.2%), 49 mild (38.0%), and 5 (3.9%) severe to critical cases. The sensitivity of throat swab was 71.32% and 92.19% at first to second PCR test. Among different modes of contact, household contacts were the most dangerous in catching with infection of COVID-19, with an incidence of 10.2%. As the increase of age for close contacts and severity of source cases, the incidence of COVID-19 presented an increasing trend from 1.8% (0-17 years) to 4.2% (60 or over years), and from 0.33% for asymptomatic, 3.3% for mild, to 6.2% for severe and critical source cases, respectively. Manifestation of expectoration in source cases was also highly associated with an increased risk of infection in their close contacts (13.6%). Secondary cases were in general clinically milder and were less likely to have common symptoms than those of source cases. Conclusions In conclusion, the proportion of asymptomatic and mild infections account for almost half of the confirmed cases among close contacts. The household contacts were the main transmission mode, and clinically more severe cases were more likely to pass the infection to their close contacts. Generally, the secondary cases were clinically milder than those of source cases.

Antibody responses to SARS-CoV-2 in COVID-19 patients: the perspective application of serological tests in clinical practice (preprint)

Background We aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice. Methods A multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. Results The positive rate for IgG reached 100% around 20 days after symptoms onset. The median day of serocon-version for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of IgG seroconversion and [≥] 4-fold increase in the IgG titers in sequential samples together diagnosed 82.9% (34/41) of the patients. Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. Conclusion IgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or [≥] 4-fold increase in the IgG titer is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.

High transmissibility of COVID-19 near symptom onset (preprint)

Background The dynamics of coronavirus disease 2019 (COVID-19) transmissibility after symptom onset remains unknown. Methods We conducted a prospective case-ascertained study on laboratory-confirmed COVID-19 cases and their contacts. Secondary clinical attack rate (considering symptomatic cases only) was analyzed for different exposure windows after symptom onset of index cases and for different exposure settings. Results Thirty-two confirmed patients were enrolled and 12 paired data (index-secondary cases) were identified among the 1,043 contacts. The secondary clinical attack rate was 0.9% (95% CI 0.5-1.7%). The attack rate was higher among those whose exposure to index cases started within five days of symptom onset (2.4%, 95% CI 1.1-4.5%) than those who were exposed later (zero case from 605 close contacts, 95% CI 0-0.61%). The attack rate was also higher among household contacts (13.6%, 95% CI 4.7-29.5%) and non-household family contacts (8.5%, 95% CI 2.4-20.3%) than that in healthcare or other settings. The higher secondary clinical attack rate for contacts near symptom onset remained when the analysis was restricted to household and family contacts. There was a trend of increasing attack rate with the age of contacts (p for trend < 0.001). Conclusions High transmissibility of COVID-19 near symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized social distancing measures are required. Rapid reduction of transmissibility over time implies that prolonged hospitalization of mild cases might not be necessary in large epidemics.