scholarly journals Assessing Viral Shedding and Infectivity of Asymptomatic or Mildly Symptomatic Patients with COVID-19 in a Later Phase

2020 ◽  
Vol 9 (9) ◽  
pp. 2924 ◽  
Author(s):  
Yujin Sohn ◽  
Su Jin Jeong ◽  
Won Suk Chung ◽  
Jong Hoon Hyun ◽  
Yae Jee Baek ◽  
...  
Keyword(s):  
Viral Rna ◽  
Community Treatment ◽  
Transmission Risk ◽  
Treatment Center ◽  
Public Health Issue ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Viral Shedding ◽  
Viral Culture ◽  
Later Phase

Background: The coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a major global public health issue. SARS-CoV-2 infection is confirmed by the detection of viral RNA using reverse transcription polymerase chain reaction (RT-PCR). Prolonged viral shedding has been reported in patients with SARS-CoV-2 infection, but the presence of viral RNA does not always correlate with infectivity. Therefore, the present study aimed to confirm the presence of viable virus in asymptomatic or mildly symptomatic patients in the later phase of the disease, more than two weeks after diagnosis. Method: Asymptomatic or mildly symptomatic COVID-19 patients who had been diagnosed with the disease at least two weeks previously and admitted to a community treatment center (CTC) from 15 March to 10 April 2020 were enrolled in this study. Nasopharyngeal and salivary swab specimens were collected from each patient. Using these specimens, RT-PCR assay and viral culture were performed. Result: In total, 48 patients were enrolled in this study. There were no significant differences in baseline characteristics between the asymptomatic and mildly symptomatic patient groups. RT-PCR assay and viral culture of SARS-CoV-2 were performed using nasopharyngeal and salivary swabs. The results of RT-PCR performed using salivary swab specimens, in terms of cycle threshold (Ct) values, were similar to those of RT-PCR using nasopharyngeal swab specimens. In addition, no viable virus could be cultured from swab specimens collected from the late-phase COVID-19 patients with prolonged viral RNA shedding. Conclusions: In conclusion, our study suggests that even if viral shedding is sustained in asymptomatic or mildly symptomatic patients with later phase of COVID-19, it can be expected that the transmission risk of the virus is low. In addition, saliva can be used as a reliable specimen for the diagnosis of SARS-CoV-2 infection.

scholarly journals Is it enough for COVID-19 screening test? Limitation of swab test and general characteristics of mild symptom patients

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110261
Author(s):  
Sungwoo Choi ◽  
Hyo Jeong Choi ◽  
Ho Jung Kim
Keyword(s):  
Screening Test ◽  
Community Treatment ◽  
Upper Respiratory Tract ◽  
Test Results ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Positive Rate ◽  
Upper Respiratory ◽  
Polymerase Chain ◽  
Discharge Criteria

The most common method for SARS-CoV-2 testing is throat or nasal swabbing by real-time reverse transcription polymerase chain reaction (RT-PCR) assay. In South Korea, drive-through swab test is used for screening system and community treatment centers (CTCs), which admit and treat confirmed COVID-19 patients with mild symptoms, are being used. This retrospective study was conducted on patients admitted to a CTC on March 6, 2020. A total of 313 patients were admitted. The nasal and throat swabs were collected from the upper respiratory tract, and a sputum test was performed to obtain lower respiratory samples. The positive rate of the first set of test, sputum test was higher than that of the swab test ( p = 0.011). In the second set of test, 1 week after the first ones, the rate of positive swab tests was relatively high ( p = 0.026). In the first set of test, 66 of 152 (43.4%) patients showed 24-h consecutive negative swab test results, when the sputum test results were considered together, that number fell to 29 patients (19.1%) ( p < 0.001). Also, in the second set of test, 63 of 164 (38.4%) patients met the discharge criteria only when the swab test was considered; that number fell to 30 (18.3%) when the sputum test results were also considered ( p < 0.001). Using the swab test alone is insufficient for screening test and discharge decision. Patients who may have positive result in the sputum test can be missed.

scholarly journals Assessment of Specimen Pooling to Conserve SARS CoV-2 Testing Resources

2020 ◽  
Vol 153 (6) ◽  
pp. 715-718 ◽  
Author(s):  
Baha Abdalhamid ◽  
Christopher R Bilder ◽  
Emily L McCutchen ◽  
Steven H Hinrichs ◽  
Scott A Koepsell ◽  
...  
Keyword(s):  
Incidence Rate ◽  
Group Testing ◽  
Viral Rna ◽  
Optimal Parameters ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Web Based ◽  
Negative Patient ◽  
Cycle Threshold ◽  
Unselected Group

Abstract Objectives To establish the optimal parameters for group testing of pooled specimens for the detection of SARS-CoV-2. Methods The most efficient pool size was determined to be five specimens using a web-based application. From this analysis, 25 experimental pools were created using 50 µL from one SARS-CoV-2 positive nasopharyngeal specimen mixed with 4 negative patient specimens (50 µL each) for a total volume of 250 µL. Viral RNA was subsequently extracted from each pool and tested using the CDC SARS-CoV-2 RT-PCR assay. Positive pools were consequently split into individual specimens and tested by extraction and PCR. This method was also tested on an unselected group of 60 nasopharyngeal specimens grouped into 12 pools. Results All 25 pools were positive with cycle threshold (Ct) values within 0 and 5.03 Ct of the original individual specimens. The analysis of 60 specimens determined that 2 pools were positive followed by identification of 2 individual specimens among the 60 tested. This testing was accomplished while using 22 extractions/PCR tests, a savings of 38 reactions. Conclusions When the incidence rate of SARS-CoV-2 infection is 10% or less, group testing will result in the saving of reagents and personnel time with an overall increase in testing capability of at least 69%.

scholarly journals Inference of Active Viral Replication in Cases with Sustained Positive RT-PCRs for SARS-CoV-2

2020 ◽  
Author(s):  
Cristina Rodríguez-Grande ◽  
Javier Adán-Jiménez ◽  
Pilar Catalán ◽  
Luis Alcalá ◽  
Agustín Estévez ◽  
...  
Keyword(s):  
Housekeeping Gene ◽  
Viral Rna ◽  
Hiv Positive ◽  
Rt Pcr ◽  
Specific Detection ◽  
E Gene ◽  
Viral Shedding ◽  
Active Viral Replication ◽  
Age Range ◽  
Viral Genomic Rna

Objectives: The purpose of this study was to detect COVID-19 cases with persistent positive RT-PCR results for SARS-CoV-2, for which viable virus can be inferred, due to the presence of subgenomic (SG) viral RNA, which is expressed only in replicating viruses. Methods: RNA remnants, purified from diagnostic nasopharyngeal specimens, were used as templates for RT-PCR specific detection of SG E gene RNA. As controls, we also detected viral genomic RNA for the E gene and/or a human housekeeping gene (RNase P). Results: We assessed the samples of 60 RT-PCR-positive cases with a prolonged viral SARS-CoV-2 shedding (24-101 days) since the first diagnostic RT-PCR. SG viral RNA was detected in 12/60 (20%) of the persistent cases, 28-79 days after the onset of symptoms. The age range of the cases with prolonged viral shedding and presence of SG RNA was quite wide (40-100 years), and they were equally distributed between males (42%) and females (58%). None was HIV positive, although seven were immunosuppressed. According to the severity of the COVID-19 episodes they were mild (40%), intermediate (20%), and severe (40%) Conclusion: In a percentage of persistent positive SARS-CoV-2 PCR positive cases the presence of actively replicating virus may be inferred, far beyond diagnosis. We should not assume a universal lack of infectiousness for COVID-19 cases with prolonged viral shedding.

scholarly journals Diabetes mellitus is a risk factor for prolonged SARS-CoV-2 viral shedding in lower respiratory tract samples of critically ill patients

Endocrine ◽  
2020 ◽  
Vol 70 (3) ◽  
pp. 454-460 ◽  
Author(s):  
Niccolò Buetti ◽  
Pierpaolo Trimboli ◽  
Timothy Mazzuchelli ◽  
Elia Lo Priore ◽  
Carlo Balmelli ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Cox Model ◽  
Viral Rna ◽  
Rt Pcr ◽  
Viral Shedding

Abstract Purpose The length of time a critically ill coronavirus disease 2019 (COVID-19) patient remains infectious and should therefore be isolated remains unknown. This prospective study was undertaken in critically ill patients to evaluate the reliability of single negative real-time polymerase chain reaction (RT-PCR) in lower tracheal aspirates (LTA) in predicting a second negative test and to analyze clinical factors potentially influencing the viral shedding. Methods From April 9, 2020 onwards, intubated COVID-19 patients treated in the intensive care unit were systematically evaluated for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by RT-PCR of nasopharyngeal swabs and LTA. The time to negativity was defined as the time between the onset of symptoms and the viral clearance in LTA. In order to identify risk factors for prolonged viral shedding, we used univariate and multivariate Cox proportional hazards models. Results Forty-eight intubated SARS-CoV-2 patients were enrolled. Overall, we observed that the association of the first negative RT-PCR with a second negative result was 96.7%. Median viral shedding was 25 (IQR: 21.5–28) days since symptoms’ onset. In the univariate Cox model analysis, type 2 diabetes mellitus was associated with a prolonged viral RNA shedding (hazard ratio [HR]: 0.41, 95% CI: 0.06–3.11, p = 0.04). In the multivariate Cox model analysis, type 2 diabetes was associated with a prolonged viral RNA shedding (HR: 0.31, 95% CI: 0.11–0.89, p = 0.029). Conclusion Intubated patients with type 2 diabetes mellitus may have prolonged SARS-CoV-2 shedding. In critically ill COVID-19 patients, one negative LTA should be sufficient to assess and exclude infectivity.

Detection of Colorado Tick Fever viral RNA in acute human serum samples by a quantitative real-time RT-PCR assay

2007 ◽  
Vol 140 (1-2) ◽  
pp. 43-48 ◽  
Author(s):  
Amy J. Lambert ◽  
Olga Kosoy ◽  
Jason O. Velez ◽  
Brandy J. Russell ◽  
Robert S. Lanciotti
Keyword(s):  
Human Serum ◽  
Real Time ◽  
Viral Rna ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Serum Samples ◽  
Human Serum Samples

Delayed oseltamivir treatment is associated with longer viral shedding of pandemic (H1N1) 2009 virus

2011 ◽  
Vol 140 (5) ◽  
pp. 814-817 ◽  
Author(s):  
Y. H. LEUNG ◽  
W. L. LIM ◽  
M. H. WONG ◽  
S. K. CHUANG
Keyword(s):  
Influenza Pandemic ◽  
Onset Date ◽  
Pandemic H1n1 ◽  
Rt Pcr ◽  
Illness Onset ◽  
Viral Shedding ◽  
Viral Culture ◽  
Polymerase Chain ◽  
Pandemic H1n1 2009 ◽  
Kinetics Of

SUMMARYDuring the early phase of the influenza pandemic in 2009, all cases of laboratory-confirmed pandemic (H1N1) 2009 (pH1N1) infection required compulsory isolation in hospital. These cases were offered oseltamivir treatment and only allowed to be discharged from the hospital when three consecutive respiratory specimens were negative for the virus by reverse transcription–polymerase chain reaction (RT–PCR). We reviewed the case records of these patients to assess the viral shedding kinetics of the pH1N1 virus. We defined viral shedding duration as the interval from illness onset date to the date of collection of the last positive specimen from the patients. Fifty-six patients were included in the study, of whom 96% received oseltamivir. The median viral shedding duration of pH1N1 virus by viral culture and RT–PCR were 3 days and 4 days, respectively. Patients who started oseltamivir treatment >48 h after onset had a significantly longer median viral shedding duration by viral culture than those who started treatment within 48 h of onset (4 days vs. 2 days, P=0·014).

scholarly journals Factors affecting duration of SARS-Cov-2 viral shedding in mildly symptomatic patients isolated in a community facility

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257565
Author(s):  
Hui Mei Cheng ◽  
Xiahong Zhao ◽  
Wei Shyann Lim ◽  
Beatrice Jia Min Tan ◽  
Hong Liang Tey
Keyword(s):  
Vital Signs ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Systematic Analysis ◽  
Factors Affecting ◽  
Viral Shedding ◽  
Laboratory Investigations ◽  
Baseline Characteristics ◽  
Concomitant Medications ◽  
Test Result

Introduction Mildly symptomatic cases of Covid-19 in previously-well individuals form the majority of infections and also serve as potent vectors of transmission. The factors affecting the duration of SARS-CoV-2 RNA viral shedding (DVS) in these patients remain largely unknown. Objectives To perform a systematic analysis of the clinical, radiologic, laboratory investigations in patients with few comorbidities infected with mild Covid-19 to identify factors associated with the DVS. Methods In this retrospective cohort study, patients with mild or asymptomatic Covid-19 were included. Baseline characteristics including age, nationality, comorbidities, concomitant medications, and type of isolation arrangement in the facility (single or in pairs) were collected. Clinical features and radiologic/haematologic findings were also collected. Taking day 28 as the cut-off, 187 patients who had a negative swab result up to day 28 (no prolonged DVS) were compared to 126 patients with a persistently positive result on or after day 28 (prolonged DVS). Results Of 964 consecutive patients included, 851 (88.3%) patients were symptomatic. 266 patients had a documented negative RT-PCR assay with a median DVS of 25 days (range: 13 to 96 days; interquartile range (IQR): 22 to 33 days). Patients isolated in pairs were associated with prolonged DVS (OR: 2.7; 95% CI: 1.7 to 4.5; p<0.0001) compared to those isolated individually. Among vital signs, only tachycardia was associated with prolonged DVS (OR: 2.6; 95% CI: 1.0 to 7.1; p = 0.03). Amongst investigations, only a raised CRP was associated with prolonged DVS (OR: 2.7; 95% CI: 1.1 to 6.8; p = 0.02). Conclusions In young, mildly symptomatic Covid-19 patients, prolonged DVS was associated with being isolated in pairs compared to individually. In situations where a negative RT-PCR test result is required, retesting in patients who were not isolated individually, or who had baseline tachycardia or a raised CRP, may be delayed to increase the yield of a negative result.

scholarly journals Transmission potential of vaccinated and unvaccinated persons infected with the SARS-CoV-2 Delta variant in a federal prison, July-August 2021

2021 ◽  
Author(s):  
Phillip P. Salvatore ◽  
Christine C. Lee ◽  
Sadia Sleweon ◽  
David W. McCormick ◽  
Lavinia Nicolae ◽  
...  
Keyword(s):  
Rt Pcr ◽  
Federal Prison ◽  
Transmission Potential ◽  
Vaccination Rates ◽  
Viral Shedding ◽  
Viral Culture ◽  
Culture Positivity ◽  
Health Practitioners ◽  
Polymerase Chain ◽  
Public Health Practitioners

Background The extent to which vaccinated persons who become infected with SARS-CoV-2 contribute to transmission is unclear. During a SARS-CoV-2 Delta variant outbreak among incarcerated persons with high vaccination rates in a federal prison, we assessed markers of viral shedding in vaccinated and unvaccinated persons. Methods Consenting incarcerated persons with confirmed SARS-CoV-2 infection provided mid-turbinate nasal specimens daily for 10 consecutive days and reported symptom data via questionnaire. Real-time reverse transcription-polymerase chain reaction (RT-PCR), viral whole genome sequencing, and viral culture was performed on these nasal specimens. Duration of RT-PCR positivity and viral culture positivity was assessed using survival analysis. Results A total of 978 specimens were provided by 95 participants, of whom 78 (82%) were fully vaccinated and 17 (18%) were not fully vaccinated. No significant differences were detected in duration of RT-PCR positivity among fully vaccinated participants (median: 13 days) versus those not fully vaccinated (median: 13 days; p=0.50), or in duration of culture positivity (medians: 5 days and 5 days; p=0.29). Among fully vaccinated participants, overall duration of culture positivity was shorter among Moderna vaccine recipients versus Pfizer (p=0.048) or Janssen (p=0.003) vaccine recipients. Conclusions As this field continues to develop, clinicians and public health practitioners should consider vaccinated persons who become infected with SARS-CoV-2 to be no less infectious than unvaccinated persons. These findings are critically important, especially in congregate settings where viral transmission can lead to large outbreaks.

scholarly journals Sensitive Detection and Quantification of SARS-CoV-2 by Multiplex Droplet Digital RT-PCR

2020 ◽  
Author(s):  
Remco de Kock ◽  
Mieke Baselmans ◽  
Volkher Scharnhorst ◽  
Birgit Deiman
Keyword(s):  
Simultaneous Detection ◽  
Housekeeping Gene ◽  
Multiplex Assay ◽  
Viral Rna ◽  
Sensitive Detection ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Assay Sensitivity ◽  
One Step ◽  
Detection And Quantification

Abstract Purpose. We aimed to develop a one-step droplet digital RT-PCR (RT-ddPCR) multiplex assay that allows for sensitive detection of SARS-CoV-2 RNA with respect to human derived RNA and could be used for triage and monitoring of Covid-19 patients. Methods. A one step RT-ddPCR multiplex assay was developed for simultaneous detection of SARS-CoV-2 E, RdRp and N viral RNA, and human Rpp30 DNA and GUSB mRNA, for internal nucleic acid (NA) extraction and RT-PCR control. Dilution series of viral RNA transcripts were prepared in water and total NA extract of Covid-19 negative patients. As reference assay, an E-GUSB duplex RT-PCR was used. Results. Assay sensitivity of the RT-PCR assay drastically decreased when SARS-CoV-2 copies were detected in a background of total NA extract compared to water, while the sensitivity of the RT-ddPCR was not affected by the total NA background. GUSB mRNA detection was used to set validity criteria to assure viral RNA and RT-PCR assay quality. In a background of at least 100 GUSB mRNA copies, 5 copies of viral RNA are reliably detectable and 10 copies viral RNA copies are reliably quantifiable. Conclusion. The present study describes a robust and sensitive one-step RT-ddPCR multiplex assay for reliable detection and quantification of SARS-CoV-2 RNA. By determining the fractional abundance of viral RNA with respect to a human housekeeping gene, viral loads from different samples can be compared, what could be used to investigate the infectiveness and to monitor Covid-19 patients.

Sign in / Sign up

Export Citation Format

Share Document