The Positive Rate of Nucleic Acid Testing and the Epidemiological Characteristics of COVID-19 in Chongqing

ObjectiveThe purpose of this study is to analyze the positive rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid testing (NAT), cases of and deaths due to SARS-CoV-2, and the epidemiological characteristics of SARS-CoV-2 to identify high-risk populations.MethodsA retrospective study in Jiulongpo district of Chongqing was conducted by performing continuous observations of the frequency of SARS-CoV-2 NAT, analyzing the data of close contacts of patients and asymptomatic carriers, and collecting epidemiological data. Data were collected from January 20, 2020, when the first case of SARS-CoV-2 infection was reported, to March 26, 2020. Descriptive statistical analysis and Cochrane–Mantel–Haenszel analysis were used to compare the positive detection rates and positive diagnostic rates of different exposure groups.ResultsA total of 7,118 people received 10,377 SARS-CoV-2 nucleic acid tests in one district, and the SARS-CoV-2 positive rates were 0.40% (18/4446) and 0.15% (4/2672) in people receiving one and ≥ two nucleic acid tests (p = 0.06), respectively. Those with suspected cases (12.35%) and close contacts (8%) had higher positive rates than people tested at fever clinics (0.39%) (p < 0.001). The median latency (range) of cases was 5 (2, 9) days, and the median time from diagnosis to recovery was 22 (14, 25) days. One recovered patient received a positive test result at 28 days after recovery when she attempted to donate blood. Six clustered cases, including one patient who died, indicated persistent human-to-human transmission. One patient who was diagnosed after death was found to have infected 13 close contacts. People working in catering and other public service departments (36.36%) and people who are unemployed and retirees (45.45%) have an increased risk of infection compared with technical staff (9.09%) and farmers (9.09%).ConclusionThe total positive rate was low in the tested population, and more effective detection ranges should be defined to improve precise and differentiated epidemic control strategies. Moreover, in asymptomatic carriers, SARS-CoV-2 tests were positive after recovery, and patients with suspected SARS-CoV-2 infection who die may pose serious potential transmission threats.

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Clinical Characteristics of 24 Asymptomatic Infections with COVID-19 Screened among Close Contacts in Nanjing, China

10.1101/2020.02.20.20025619 ◽

2020 ◽

Cited By ~ 22

Author(s):

Zhiliang Hu ◽

Ci Song ◽

Chuanjun Xu ◽

Guangfu Jin ◽

Yaling Chen ◽

...

Keyword(s):

Nucleic Acid ◽

Clinical Characteristics ◽

Close Contact ◽

Contact Tracing ◽

Severe Illness ◽

Asymptomatic Carriers ◽

Asymptomatic Infections ◽

Clinical Records ◽

Close Contacts ◽

Nucleic Acid Tests

AbstractBackgroundPrevious studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers.MethodsEpidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed.FindingsNone of the 24 asymptomatic cases presented any obvious symptoms before nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue, etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and 5 (20.8%) presented stripe shadowing in the lungs. The remaining 7 (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These 7 cases were younger (median age: 14.0 years; P = 0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia.InterpretationThe asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged.

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Efficacy and Safety of Lianhuaqingwen Capsules for the Prevention of Coronavirus Disease 2019: A Prospective Open-Label Controlled Trial

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/7962630 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Xiaowei Gong ◽

Boyun Yuan ◽

Yadong Yuan ◽

Fengju Li

Keyword(s):

Nucleic Acid ◽

Treatment Group ◽

Close Contact ◽

Controlled Trial ◽

Control Group ◽

Open Label ◽

Medical Observation ◽

Observation Period ◽

Close Contacts ◽

Nucleic Acid Tests

Coronavirus disease 2019 (COVID-19) has become a global pandemic. Community and close contact exposures continue to drive the COVID-19 pandemic. There is no confirmed effective treatment for suspected cases and close contacts. Lianhuaqingwen (LH) capsules, a repurposed Chinese herbal product that is currently on the market, have proven effective for influenza and COVID-19. To determine the safety and efficacy of LH capsules for the prevention of COVID-19, we conducted a prospective open-label controlled trial of LH capsules on subjects who had close contact with people infected with COVID-19. Subjects received LH capsules (4 capsules, three times daily) or the usual medical observation for 14 days. The primary endpoint was the rate of positive nucleic acid tests of nasal and pharyngeal swabs during the quarantine medical observation period. We included 1976 patients, including 1101 in the treatment group and 875 in the control group. The rate of positive nucleic acid tests in the treatment group was significantly lower than that in the control group (0.27% vs. 1.14%, respectively; mean difference: −0.87%; 95% CI: −1.83 to −0.13; p = 0.0174 ) during the quarantine medical observation period (14 days). Among subjects with different close contact states, there was no significant difference in the rate of positive nucleic acid test results among close contacts in the treatment group and the control group (6.45% vs. 11.43%, respectively; p = 0.6762 ). Among secondary close contacts, the rate of positive nucleic acid tests in the treatment group was significantly lower than that in the control group (0.09% vs. 0.71%, respectively; p = 0.0485 ). No serious adverse events were reported. Taken together, and in light of the safety and effectiveness profiles, these results show that LH capsules can be considered to prevent the progression of COVID-19 after close contact with an infected person. This trial is registered with ChiCTR2100043012.

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Repeated Nucleic Acid Tests Are Necessary for Early Diagnosis of Atypical COVID-19: A Case Report

Nano LIFE ◽

10.1142/s179398442040005x ◽

2020 ◽

Vol 10 (01n02) ◽

pp. 2040005 ◽

Cited By ~ 1

Author(s):

Lihong Qu ◽

Wujun Xiong ◽

Chenghui Fan ◽

Sheng Kang

Keyword(s):

Nucleic Acid ◽

Early Diagnosis ◽

Ct Scan ◽

Infected Individual ◽

Left Lung ◽

Atypical Symptoms ◽

First Case ◽

History Of ◽

Ground Glass Nodules ◽

Nucleic Acid Tests

In Wuhan, China, the first case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported on December 8, 2019. The patient’s symptoms included fever, coughing and breathing difficulties. According to the sixth China version of 2019 coronavirus disease (COVID-19) diagnostic criteria, some patients with COVID-19 may present atypical symptoms and have negative nucleic acid tests (NATs), possibly leading to misdiagnosis and viral transmission. Our patient was a 29-year-old woman who complained of a three-day history of nasal obstruction, and no fever, coughing or breathing difficulties were noted. Physical examination revealed no obvious signs of pneumonia. On January 16, 2020, the patient flew from Wuhan to Germany for a business trip and returned to Shanghai on January 28, a passenger on her flight was tested positive for SARS-CoV-2 later. Although two consecutive NATs performed at an interval of 24 h were negative, considering her direct contact with a SARS-CoV-2-infected individual, a 64-slice computed tomography (CT) scan showed a few scattered ground-glass nodules in the left lung, suggesting possible viral pneumonia. Given the clinical characteristics, epidemiological records, CT findings and a third positive NAT, our patient was diagnosed with COVID-19. The combination of history of epidemiology, clinical symptom, lung CT scan and routine blood test will improve the clinical diagnosis of asymptomatic COVID-19, but the early diagnosis of COVID-19 can be confirmed only by the repeated NATs.

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Effects of prolonged incubation period and centralized quarantine on the COVID-19 outbreak in Shijiazhuang, China: a modeling study

BMC Medicine ◽

10.1186/s12916-021-02178-z ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Wenlong Zhu ◽

Mengxi Zhang ◽

Jinhua Pan ◽

Ye Yao ◽

Weibing Wang

Keyword(s):

Nucleic Acid ◽

Incubation Period ◽

Likelihood Method ◽

Cumulative Number ◽

Nucleic Acid Testing ◽

Prolonged Incubation ◽

Serial Interval ◽

Epidemic Period ◽

Epidemiological Characteristics ◽

The Impact

Abstract Background From 2 January to 14 February 2021, a local outbreak of COVID-19 occurred in Shijiazhuang, the capital city of Hebei Province, with a population of 10 million. We analyzed the characteristics of the local outbreak of COVID-19 in Shijiazhuang and evaluated the effects of serial interventions. Methods Publicly available data, which included age, sex, date of diagnosis, and other patient information, were used to analyze the epidemiological characteristics of the COVID-19 outbreak in Shijiazhuang. The maximum likelihood method and Hamiltonian Monte Carlo method were used to estimate the serial interval and incubation period, respectively. The impact of incubation period and different interventions were simulated using a well-fitted SEIR+q model. Results From 2 January to 14 February 2021, there were 869 patients with symptomatic COVID-19 in Shijiazhuang, and most cases (89.6%) were confirmed before 20 January. Overall, 40.2% of the cases were male, 16.3% were aged 0 to 19 years, and 21.9% were initially diagnosed as asymptomatic but then became symptomatic. The estimated incubation period was 11.6 days (95% CI 10.6, 12.7 days) and the estimated serial interval was 6.6 days (0.025th, 0.975th: 0.6, 20.0 days). The results of the SEIR+q model indicated that a longer incubation period led to a longer epidemic period. If the comprehensive quarantine measures were reduced by 10%, then the nucleic acid testing would need to increase by 20% or more to minimize the cumulative number of cases. Conclusions Incubation period was longer than serial interval suggested that more secondary transmission may occur before symptoms onset. The long incubation period made it necessary to extend the isolation period to control the outbreak. Timely contact tracing and implementation of a centralized quarantine quickly contained this epidemic in Shijiazhuang. Large-scale nucleic acid testing also helped to identify cases and reduce virus transmission.

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Analysis of the positive rate of 4254 cases of COVID‐19 nucleic acid tests in different aites in Wuhan, China

Journal of Medical Virology ◽

10.1002/jmv.26323 ◽

2020 ◽

Vol 93 (2) ◽

pp. 870-877

Author(s):

Kebin Deng ◽

Hui Li ◽

Xin Ma ◽

Bianbian Yu ◽

Xinlin Yi ◽

...

Keyword(s):

Nucleic Acid ◽

Positive Rate ◽

Nucleic Acid Tests

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Gastrointestinal symptoms and fecal nucleic acid testing of children with 2019 coronavirus disease: a systematic review and meta-analysis

Scientific Reports ◽

10.1038/s41598-020-74913-0 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Ji-gan Wang ◽

Hai-rong Cui ◽

Hua-bo Tang ◽

Xiu-li Deng

Keyword(s):

Nucleic Acid ◽

Respiratory Tract ◽

Case Reports ◽

Meta Analysis ◽

Clinical Manifestations ◽

Gastrointestinal Symptoms ◽

Nucleic Acid Detection ◽

Nucleic Acid Testing ◽

Pooled Prevalence ◽

Positive Rate

Abstract In order to understand the clinical manifestations and incidence of gastrointestinal symptoms of coronavirus disease (COVID-19) in children and discuss the importance of fecal nucleic acid testing.We retrospectively analyzed studies on gastrointestinal symptoms and fecal nucleic acid detection in pediatric COVID-19 patients from January 1, 2020 to August 10, 2020, including prospective clinical studies and case reports. The results of fecal nucleic acid detection were analyzed systematically. Stata12.0 software was used for meta-analysis.The results showed that the most common gastrointestinal symptoms in children with COVID-19 were vomiting and diarrhea, with a total incidence of 17.7% (95% Cl 13.9–21.5%). However, the prevalence of gastrointestinal symptoms in other countries (21.1%, 95% CI 16.5–25.7%) was higher compared to China (12.9%, 95% CI 8–17.7%). In Wuhan, the pooled prevalence was much higher (41.3%, 95% CI 3.2–79.4%) compared to areas outside Wuhan in China (7.1%, 95% CI 4.0–10.3%). The positive rate of fecal nucleic acid testing in COVID-19 children was relatively high at 85.8% (91/106). Additionally, 71.2% (52/73) were still positive for fecal nucleic acid after respiratory tract specimens turned negative. One and two weeks after the respiratory tract specimens turned nucleic acid-negative, 45.2% (33/73) and 34.2% (25/73) patients, respectively, remained fecal nucleic acid-positive. The longest interval between the respiratory tract specimens turning negative and fecal specimens turning negative exceeded 70 days. Conclusions and relevance: gastrointestinal symptoms in pediatric COVID-19 are relatively common. Attention should be paid to the detection of fecal nucleic acids in children. Fecal nucleic acid-negative status should be considered as one of the desegregation standards.

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Improved Early Recognition of Coronavirus Disease-2019 (COVID-19): Single-Center Data from a Shanghai Screening Hospital

Archives of Iranian Medicine ◽

10.34172/aim.2020.10 ◽

2020 ◽

Vol 23 (4) ◽

pp. 272-276 ◽

Cited By ~ 6

Author(s):

Ling Peng ◽

Kang-Yong Liu ◽

Fei Xue ◽

Ya-Fang Miao ◽

Ping-An Tu ◽

...

Keyword(s):

Nucleic Acid ◽

Clinical Laboratory ◽

Clinical Symptoms ◽

Early Recognition ◽

Case Reports ◽

Clinical Manifestations ◽

Nucleic Acid Testing ◽

Single Center ◽

Cross Sectional ◽

Epidemiological Characteristics

Background: In December 2019, an outbreak of a novel coronavirus disease (COVID-19; previously known as 2019-nCoV) was reported in Wuhan, Hubei province, China, which has subsequently affected more than 200 countries worldwide including Europe, North America, Oceania, Africa and other places. The number of infected people is rapidly increasing, while the diagnostic method of COVID-19 is only by nucleic acid testing. Objective: To explain the epidemiological characteristics, clinical features, imaging manifestations and to judge diagnostic value of COVID-19 by analyzing the clinical data of COVID-19 suspected and confirmed patients in a non-outbreak, Shanghai, China. To clarify the early epidemiology and clinical characteristics about COVID-19. Methods: Cross-sectional, single-center case reports of the 86 patients screened at Zhoupu Hospital in Pudong New District, Shanghai, China, from January 23 to February 16, 2020. Epidemiology, demography, clinical, laboratory and chest CTs were collected and analyzed. The screened patients were divided into COVID-19 and non-COVID-19 based on nucleic acid test results. Results: Of the 86 screened patients, 11 were confirmed (12.8%) by nucleic acid testing (mean age 40.73 ± 11.32, 5 males). No significant differences were found in clinical symptoms including fever, cough, dyspnea, sore throat, and fatigue (P > 0.05). No statistical difference was observed in plasma C-reactive protein (CRP) between the two groups (COVID-19 and non-COVID-19 ) of patients (P = 0.402), while the white blood cell count and lymphocyte count of the confirmed patients were slightly lower than those of the suspected patients (P < 0.05). Some non-COVID-19 chest CTs also showed subpleural lesions, such as ground-glass opacities (GGO) combined with bronchiectasis; or halo nodules distributed under the pleura with focal GGO; consolidation of subpleural distribution or combined with air bronchi sign and vascular bundle sign, etc. Conclusion: The early clinical manifestations and imaging findings of COVID-19 are not characteristic in non-outbreak areas. Etiological testing should be performed as early as possible for clinically suspected patients.

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Highlighted Prospects of an IgM/IgG Antibodies Test in Identifying Individuals With Asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

Archives of Pathology & Laboratory Medicine ◽

10.5858/arpa.2020-0310-sa ◽

2020 ◽

Vol 145 (1) ◽

pp. 39-45

Author(s):

Yaqing Li ◽

Qiang He ◽

Rizhen Yu ◽

Hui Jiang ◽

Weizhong Wang ◽

...

Keyword(s):

Nucleic Acid ◽

Severe Acute Respiratory Syndrome ◽

Ct Scanning ◽

Immunoglobulin M ◽

Antibody Detection ◽

Igg Antibodies ◽

Igg Antibody ◽

Imaging Results ◽

Close Contacts ◽

Nucleic Acid Tests

Context.— Covert severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections could be seeding new outbreaks. How to identify asymptomatic SARS-CoV-2 infections early has become a global focus. Objective.— To explore the roles of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies detection, nucleic acid tests, and computed tomography (CT) scanning to identify asymptomatic SARS-CoV-2 infection. Design.— The clinical data of 389 individuals with close contacts, including in general characteristics, SARS-CoV-2 etiology, serum-specific IgM and IgG antibody detection and CT imaging results, were systematically analyzed. Results.— The present study showed that only 89 of 389 individuals with close contacts were positive after the first nucleic acid test, while 300 individuals were still negative after 2 nucleic acid tests. Among the 300 individuals, 75 did not have pneumonia, and the other 225 individuals had pulmonary imaging changes. A total of 143 individuals were eventually diagnosed as having asymptomatic infection through IgM antibody and IgG antibody detection. The sensitivity, specificity, and false-negative rate of IgM and IgG antibody detection were approximately 97.1% (347 of 357), 95.3% (204 of 214), and 4.67% (10 of 214), respectively. It also indicated that during approximately 2 weeks, most individuals were both IgM positive and IgG positive, accounting for 68.57% (72 of 105). During approximately 3 weeks, the proportion of IgM-positive and IgG-positive individuals decreased to 8.57% (9 of 105), and the proportion of IgM-negative and IgG-positive individuals increased to 76.19% (80 of 105). Conclusions.— There are highlighted prospects of IgM/IgG antibody detection as a preferred method in identifying the individuals with asymptomatic SARS-CoV-2 infection, especially combined with nucleic acid tests and pulmonary CT scanning.

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Clinical Outcomes in 55 Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Who Were Asymptomatic at Hospital Admission in Shenzhen, China

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa119 ◽

2020 ◽

Vol 221 (11) ◽

pp. 1770-1774 ◽

Cited By ~ 115

Author(s):

Yanrong Wang ◽

Yingxia Liu ◽

Lei Liu ◽

Xianfeng Wang ◽

Nijuan Luo ◽

...

Keyword(s):

Nucleic Acid ◽

Young People ◽

Severe Acute Respiratory Syndrome ◽

Hospital Admission ◽

Clinical Outcomes ◽

Close Contact ◽

Nucleic Acid Testing ◽

Pharyngeal Swab ◽

Asymptomatic Carriers ◽

Novel Coronavirus

Abstract An epidemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has spread unexpectedly in Wuhan, Hubei Province, China, since December 2019. There are few reports about asymptomatic contacts of infected patients identified as positive for SARS-CoV-2 through screening. We studied the epidemiological and clinical outcomes in 55 asymptomatic carriers who were laboratory confirmed to be positive for SARS-CoV-2 through nucleic acid testing of pharyngeal swab samples. The asymptomatic carriers seldom occurred among young people (aged 18–29 years) who had close contact with infected family members. In the majority of patients, the outcome was mild or ordinary 2019 novel coronavirus disease during hospitalization.

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Improving Detection Efficiency of SARS-CoV-2 Nucleic Acid Testing

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2020.558472 ◽

2020 ◽

Vol 10 ◽

Author(s):

Jie Zhang ◽

Kecheng Li ◽

Ling Zheng ◽

Jianbo Zhang ◽

Zhilin Ren ◽

...

Keyword(s):

Nucleic Acid ◽

Symptom Onset ◽

Detection Efficiency ◽

False Negative ◽

False Negative Rate ◽

Nucleic Acid Testing ◽

Detection Rates ◽

High False Negative Rate ◽

Before And After ◽

Positive Rate

BackgroundSARS-CoV-2 nucleic acid testing (NAT) has been routinely used for COVID-19 diagnosis during this pandemic; however, there have been concerns about its high false negative rate. We dissected its detection efficiency with a large COVID-19 cohort study.MethodsWe analyzed SARS-CoV-2 NAT positive rates of 4,275 specimens from 532 COVID-19 patients in Sichuan Province with different disease severities, statuses, and stages, as well as different types and numbers of specimens.ResultsThe total positive rate of the 4,275 specimens was 37.5%. Among seven specimen types, BALF generated a 77.8% positive rate, followed by URT specimens (38.5%), sputum (39.8%), and feces/rectal swabs (34.1%). Specimens from critical cases generated a 43.4% positive rate, which was significantly higher than that of other severities. With specimens from patients at stable status, the SARS-CoV-2 positive rate was 40.6%, which was significantly higher than that of improved status (17.1%), but lower than that of aggravated status (61.5%). Notably, the positive rate of specimens from COVID-19 patients varied significantly from 85 to 95% during 3 days before and after symptom onset, to 20% at around 18 days after symptom onset. In addition, the detection rate increased from 72.1% after testing one throat swab, to 93.2% after testing three consecutive respiratory specimens from each patient.ConclusionsSARS-CoV-2 NAT detection rates vary with patient disease severity and status, specimen type, number of specimens, and especially disease progression. Sampling as close to symptom onset as possible, and consecutively collecting more than one respiratory specimen could effectively improve SARS-CoV-2 NAT detection efficiency.

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