scholarly journals Evaluation of the SARS-CoV-2 positivity ratio and upper respiratory tract viral load among asymptomatic individuals screened before hospitalization or surgery in Flanders, Belgium

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259908
Author(s):  
Laura Heireman ◽  
Steven Abrams ◽  
Peggy Bruynseels ◽  
Reinoud Cartuyvels ◽  
Lize Cuypers ◽  
...  
Keyword(s):  
Viral Load ◽  
Respiratory Tract ◽  
Age Group ◽  
Test Results ◽  
Rt Pcr ◽  
Median Viral Load ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Positivity Ratio ◽  
Second Wave

Introduction The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in the Belgian community is mainly estimated based on test results of patients with coronavirus disease (COVID-19)-like symptoms. The aim of this study was to investigate the evolution of the SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) positivity ratio and distribution of viral loads within a cohort of asymptomatic patients screened prior hospitalization or surgery, stratified by age category. Materials/Methods We retrospectively studied data on SARS-CoV-2 real-time RT-PCR detection in respiratory tract samples of asymptomatic patients screened pre-hospitalization or pre-surgery in nine Belgian hospitals located in Flanders over a 12-month period (1 April 2020–31 March 2021). Results In total, 255925 SARS-CoV-2 RT-PCR test results and 2421 positive results for which a viral load was reported, were included in this study. An unweighted overall SARS-CoV-2 real-time RT-PCR positivity ratio of 1.27% was observed with strong spatiotemporal differences. SARS-CoV-2 circulated predominantly in 80+ year old individuals across all time periods except between the first and second COVID-19 wave and in 20–30 year old individuals before the second COVID-19 wave. In contrast to the first wave, a significantly higher positivity ratio was observed for the 20–40 age group in addition to the 80+ age group compared to the other age groups during the second wave. The median viral load follows a similar temporal evolution as the positivity rate with an increase ahead of the second wave and highest viral loads observed for 80+ year old individuals. Conclusion There was a high SARS-CoV-2 circulation among asymptomatic patients with a predominance and highest viral loads observed in the elderly. Moreover, ahead of the second COVID-19 wave an increase in median viral load was noted with the highest overall positivity ratio observed in 20–30 year old individuals, indicating they could have been the hidden drivers of this wave.

scholarly journals Insufficient Sensitivity of RNA Dependent RNA Polymerase Gene of SARS-CoV-2 Viral Genome as Confirmatory Test using Korean COVID-19 Cases

2020 ◽  
Author(s):  
Soyoun Kim ◽  
Dong-Min Kim ◽  
Baeckseung Lee
Keyword(s):  
Diagnostic Methods ◽  
Confirmatory Test ◽  
Test Results ◽  
Rt Pcr ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Pcr Method ◽  
Who Guideline ◽  
Rna Polymerase Gene ◽  
Insufficient Sensitivity

Since mid-December of 2019, coronavirus disease 2019 (COVID-19) has been spreading from Wuhan, China. As of February 21, total 75,773 confirmed cases worldwide have spread to more than two dozen countries. Transmission of COVID-19 can occur early in the course of infection since SARS-CoV-2 viral loads in asymptomatic patients are similar to that in the symptomatic patients. Therefore, more sensitive diagnostic methods are needed to detect early phase of the infection to prevent secondary or tertiary spreads. Here, we compare the RT-PCR confirmatory test results using two different SARS-CoV-2 viral RNAs from two Korean COVID-19 confirmed cases.RT-PCR method targeting the RdRP gene, which was recommended by WHO guideline, was less sensitive than targeting N genes (as per CDC guideline). Because many countries follow the WHO guideline, our findings may contribute to the early diagnosis of COVID-19.

scholarly journals Viral load of SARS-CoV-2 in adults during the first and second wave of COVID-19 pandemic in Houston, TX: the potential of the super-spreader

2021 ◽  
Author(s):  
Vasanthi Avadhanula ◽  
Erin G Nicholson ◽  
Laura Ferlic-Stark ◽  
Felipe-Andres Piedra ◽  
Brittani N Blunck ◽  
...  
Keyword(s):  
Viral Load ◽  
Contingency Table ◽  
Social Dynamics ◽  
High Viral Load ◽  
Rt Pcr ◽  
Median Viral Load ◽  
Viral Shedding ◽  
The Social ◽  
Second Wave ◽  
Index Cases

Abstract Background During the COVID-19 pandemic, a minority of index cases are associated with a majority of secondary cases suggesting that super-spreaders could drive the pandemic. We identified a phenotype in individuals with extremely high viral load who could act as super-spreaders. Methods Data were analyzed from individuals tested for SARS-CoV-2 from March 18 through August 15, 2020. Outcomes were compared using contingency table and quantile regression to test the equality of medians between the pandemic waves and by viral load groups. Results Of the 11,564 samples tested, 1,319 (11.4%) were positive for SARS-CoV-2. An increase in weekly median viral load occurred in the second wave of the SARS-CoV2 pandemic. This population was more likely to be women, outpatients, symptomatic and have an extremely high or high viral load. In patients with multiple RT-PCR positive tests, the duration of viral shedding was comparable between individuals with asymptomatic/mild and mild/moderate illness severity. Conclusions We detected a small group of individuals with extremely high SARS-CoV-2 viral load with mild illness. We believe that these individuals’ characteristics could be consistent with the super-spreader phenomenon and that greater awareness of the social dynamics of these individuals is needed to understand the spread of SARS-CoV-2.

scholarly journals Viral load in upper respiratory tract of COVID-19 patients detected by digital PCR

2020 ◽  
Author(s):  
Jiankang Zhao ◽  
Haibo Li ◽  
Hui Li ◽  
Qiaoling Wu ◽  
Ke Wu ◽  
...  
Keyword(s):  
Viral Load ◽  
Respiratory Tract ◽  
Digital Pcr ◽  
Upper Respiratory Tract ◽  
Rt Pcr ◽  
Lung Lesions ◽  
Viral Loads ◽  
Ct Value ◽  
Upper Respiratory ◽  
Close Contacts

Abstract Background: Upper respiratory tract specimens are widely applicable for the diagnosis of COVID-19. To date, no study has analyzed the actual viral loads in upper respiratory tract and its relationship with the severity of lung lesions, Ct value of RT-PCR and transmission capacity in COVID-19 patients.Methods: We retrospectively enrolled nine COVID-19 patients. Clinical data and close contacts of these patients were investigated. Respiratory samples were tested for SARS-CoV-2 with both normal RT-PCR and droplet digital PCR.Results: All the COVID-19 patients complicated with pneumonia. Viral loads in nasopharyngeal swabs were accurately quantified, and they had no direct correspondence with the severity of lung lesions. The Cycle Threshold (Ct) value of RT-PCR was approximately consistent with the absolute quantification of digital PCR. The spearman correlation coefficient between them was -0.952 with P value < 0.001. Close contacts of patients with very low viral load or no detected virus were not infected.Conclusions: Viral loads in nasopharyngeal swabs, could not predict the severity of lung lesions revealed by CT in COVID-19 patients. The infectious capacity of patients with low or absent viral load in upper respiratory tract was relatively weak, and wearing mask might be helpful for lower its spread.

scholarly journals Clinical importance of reporting SARS-CoV-2 viral loads across the different stages of the COVID-19 pandemic

2020 ◽  
Author(s):  
Milo Moraz ◽  
Damien Jacot ◽  
Matthaios Papadimitriou-Olivgeris ◽  
Laurence Senn ◽  
Gilbert Greub ◽  
...  
Keyword(s):  
Viral Load ◽  
Universal Screening ◽  
Clinical Importance ◽  
Screening Strategy ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Admission Screening ◽  
Polymerase Chain

On April 25th, corresponding to the first deconfinement phase after the end of the lockdown in Switzerland, a universal admission screening strategy for COVID-19 was introduced in our hospital. All patients, including asymptomatic patients were tested for SARS-CoV-2 by quantitative reverse transcription polymerase chain reaction (RT-PCR). In addition to a qualitative answer, providing viral load values to the RT-PCR results not only helped the clinician to evaluate the stage of the infection but addressed patient contagiousness and guided infection control decisions. Here, we discuss the importance of reporting viral load values when a shift from a symptomatic to a universal screening strategy was performed.

scholarly journals Transmissibility of COVID-19 depends on the viral load around onset in adult and symptomatic patients

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243597
Author(s):  
Hitoshi Kawasuji ◽  
Yusuke Takegoshi ◽  
Makito Kaneda ◽  
Akitoshi Ueno ◽  
Yuki Miyajima ◽  
...  
Keyword(s):  
Viral Load ◽  
Linear Regression ◽  
University Hospital ◽  
Sample Collection ◽  
Initial Sample ◽  
Median Viral Load ◽  
Secondary Transmission ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Non Linear

Objective To investigate the relationship between viral load and secondary transmission in novel coronavirus disease 2019 (COVID-19). Methods Epidemiological and clinical data were obtained from immunocompetent laboratory-confirmed patients with COVID-19 who were admitted to and/or from whom viral loads were measured at Toyama University Hospital. Using a case-control approach, index patients who transmitted the disease to at least one other patient were analysed as “cases” (index patients) compared with patients who were not the cause of secondary transmission (non-index patients, analysed as “controls”). The viral load time courses were assessed between the index and non-index symptomatic patients using non-linear regression employing a standard one-phase decay model. Results In total, 28 patients were included in the analysis. Median viral load at the initial sample collection was significantly higher in symptomatic than in asymptomatic patients and in adults than in children. Among symptomatic patients (n = 18), non-linear regression models showed that the estimated viral load at onset was higher in the index than in the non-index patients (median [95% confidence interval]: 6.6 [5.2–8.2] vs. 3.1 [1.5–4.8] log copies/μL, respectively). In adult (symptomatic and asymptomatic) patients (n = 21), median viral load at the initial sample collection was significantly higher in the index than in the non-index patients (p = 0.015, 3.3 vs. 1.8 log copies/μL, respectively). Conclusions High nasopharyngeal viral loads around onset may contribute to secondary transmission of COVID-19. Viral load may help provide a better understanding of why transmission is observed in some instances, but not in others, especially among household contacts.

Detection of SARs CoV-2 during initial phase of pandemic from population of banas kantha district of Gujarat-India with special emphasis on pooled samples

2021 ◽  
Vol 7 (4) ◽  
pp. 295-299
Author(s):  
Hiren Patel ◽  
Parijat N Goswami
Keyword(s):  
Viral Load ◽  
Age Groups ◽  
High Viral Load ◽  
Rt Pcr ◽  
Viral Loads ◽  
Corona Virus ◽  
Asymptomatic Patients ◽  
Care Workers ◽  
Pcr Method ◽  
Pharynx Swab

Corona virus (SARs CoV-2) has caused immense effect on morbidity and mortality of the population globally. We undertook this study as we are a part of one of the network laboratories of ICMR to test the patient’s sample by RT PCR for the ORF 1 ab gene of corona virus. : For a period of one and half months (14 April to 31 May 2020) we tested the nasopharynx and oro-pharynx swab samples sent to us in VTM from the assigned districts of Gujarat. All the samples were subjected to RT PCR method by following standard methods. Total of 9.04%(256/2833) population was positive and 4.73%(139/2833) belonged to age groups 21-40 and 2.33% (66/2833) to 41-60yrs. Above the age of 60yrs there were only 0.95% (22/2833) cases which were positive. It was advantageous to pool the samples. Out of the number of pools prepared, we reported around 80% negative and rest were positive in pools. The study also included association of viral load and infectivity. We found that 12% of the asymptomatic people and 5.1% of symptomatic individuals had high viral load. : It is seen that the incidence of Novel corona virus -19 detection by RT PCR is a reliable method and the establishment of the Ct value and infectivity of the patient to the health care workers and relatives needs to be taken care of. Also, the study presents asymptomatic patients having high viral loads being highly infective.

scholarly journals Viral load dynamics in transmissible symptomatic patients with COVID-19

2020 ◽  
Author(s):  
Hitoshi Kawasuji ◽  
Yusuke Takegoshi ◽  
Makito Kaneda ◽  
Akitoshi Ueno ◽  
Yuki Miyajima ◽  
...  
Keyword(s):  
Viral Load ◽  
University Hospital ◽  
Linear Regression Models ◽  
Sample Collection ◽  
Median Viral Load ◽  
Secondary Transmission ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Novel Coronavirus ◽  
The Relationship

AbstractTo investigate the relationship between viral load and secondary transmission in novel coronavirus disease 2019 (COVID-19), we reviewed epidemiological and clinical data obtained from immunocompetent laboratory-confirmed patients with COVID-19 at Toyama University Hospital. In total, 28 patients were included in the analysis. Median viral load at the initial sample collection was significantly higher in adults than in children and in symptomatic than in asymptomatic patients. Among symptomatic patients, non-linear regression models showed that the estimated viral load at onset was higher in the index (patients who transmitted the disease to at least one other patient) than in the non-index patients (patients who were not the cause of secondary transmission; median [95% confidence interval]: 6.6 [5.2–8.2] vs. 3.1 [1.5–4.8] log copies/μL, respectively). High nasopharyngeal viral loads around onset may contribute to secondary transmission of COVID-19.Article Summary LineHigh nasopharyngeal viral load around the onset may contributes to secondary transmission of COVID-19.

scholarly journals Implementing SARS-CoV-2 Rapid Antigen Testing in the Emergency Ward of a Swiss University Hospital: The INCREASE Study

2021 ◽  
Vol 9 (4) ◽  
pp. 798
Author(s):  
Giorgia Caruana ◽  
Antony Croxatto ◽  
Eleftheria Kampouri ◽  
Antonios Kritikos ◽  
Onya Opota ◽  
...  
Keyword(s):  
Immunoglobulin A ◽  
University Hospital ◽  
Lower Sensitivity ◽  
Clinical Settings ◽  
Rt Pcr ◽  
Emergency Ward ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Asymptomatic Subjects ◽  
Antigen Testing

Following the Swiss Federal Office of Public Health (FOPH) authorization of the rapid antigen test (RAT), we implemented the use of the RAT in the emergency ward of our university hospital for patients’ cohorting. RAT triaging in association with RT-PCR allowed us to promptly isolate positive patients and save resources. Among 532 patients, overall sensitivities were 48.3% for Exdia and 41.2% for Standard Q®, PanbioTM and BD Veritor™. All RATs exhibited specificity above 99%. Sensitivity increased to 74.6%, 66.2%, 66.2% and 64.8% for Exdia, Standard Q®, PanbioTM and BD Veritor™, respectively, for viral loads above 105 copies/mL, to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/mL and 100% for viral loads above 107 copies/mL. Sensitivity was significantly higher for patients with symptoms onset within four days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with the evolution of symptoms longer than four days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Among COVID-19 asymptomatic patients, sensitivity was 33%. All Immunoglobulin-A-positive patients resulted negative for RAT. The RAT might represent a useful resource in selected clinical settings as a complementary tool in RT-PCR for rapid patient triaging, but the lower sensitivity, especially in late presenters and COVID-19 asymptomatic subjects, must be taken into account.

scholarly journals Performance of the Innova SARS-CoV-2 antigen rapid lateral flow test in the Liverpool asymptomatic testing pilot: population based cohort study

BMJ ◽  
2021 ◽  
pp. n1637 ◽  
Author(s):  
Marta García-Fiñana ◽  
David M Hughes ◽  
Christopher P Cheyne ◽  
Girvan Burnside ◽  
Mark Stockbridge ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Viral Load ◽  
Predictive Value ◽  
High Viral Load ◽  
Test Results ◽  
Chain Reaction ◽  
Viral Loads ◽  
Flow Test ◽  
Polymerase Chain ◽  
Lateral Flow Test

Abstract Objective To assess the performance of the SARS-CoV-2 antigen rapid lateral flow test (LFT) versus polymerase chain reaction testing in the asymptomatic general population attending testing centres. Design Observational cohort study. Setting Community LFT pilot at covid-19 testing sites in Liverpool, UK. Participants 5869 asymptomatic adults (≥18 years) voluntarily attending one of 48 testing sites during 6-29 November 2020. Interventions Participants were tested using both an Innova LFT and a quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) test based on supervised self-administered swabbing at testing sites. Main outcome measures Sensitivity, specificity, and predictive values of LFT compared with RT-qPCR in an epidemic steady state of covid-19 among adults with no classic symptoms of the disease. Results Of 5869 test results, 22 (0.4%) LFT results and 343 (5.8%) RT-qPCR results were void (that is, when the control line fails to appear within 30 minutes). Excluding the void results, the LFT versus RT-qPCR showed a sensitivity of 40.0% (95% confidence interval 28.5% to 52.4%; 28/70), specificity of 99.9% (99.8% to 99.99%; 5431/5434), positive predictive value of 90.3% (74.2% to 98.0%; 28/31), and negative predictive value of 99.2% (99.0% to 99.4%; 5431/5473). When the void samples were assumed to be negative, a sensitivity was observed for LFT of 37.8% (26.8% to 49.9%; 28/74), specificity of 99.6% (99.4% to 99.8%; 5431/5452), positive predictive value of 84.8% (68.1% to 94.9%; 28/33), and negative predictive value of 93.4% (92.7% to 94.0%; 5431/5814). The sensitivity in participants with an RT-qPCR cycle threshold (Ct) of <18.3 (approximate viral loads >10 6 RNA copies/mL) was 90.9% (58.7% to 99.8%; 10/11), a Ct of <24.4 (>10 4 RNA copies/mL) was 69.4% (51.9% to 83.7%; 25/36), and a Ct of >24.4 (<10 4 RNA copies/mL) was 9.7% (1.9% to 23.7%; 3/34). LFT is likely to detect at least three fifths and at most 998 in every 1000 people with a positive RT-qPCR test result with high viral load. Conclusions The Innova LFT can be useful for identifying infections among adults who report no symptoms of covid-19, particularly those with high viral load who are more likely to infect others. The number of asymptomatic adults with lower Ct (indicating higher viral load) missed by LFT, although small, should be considered when using single LFT in high consequence settings. Clear and accurate communication with the public about how to interpret test results is important, given the chance of missing some cases, even at high viral loads. Further research is needed to understand how infectiousness is reflected in the viral antigen shedding detected by LFT versus the viral loads approximated by RT-qPCR.

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