scholarly journals Clinical characteristics and viral load dynamics of COVID-19 in a mildly or moderately symptomatic outpatient sample

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258970
Author(s):  
Amanda Caplan ◽  
Kelly W. Bates ◽  
Carla Brioni ◽  
Aileen Santos ◽  
Linda M. Sabatini ◽  
...  
Keyword(s):  
Viral Load ◽  
Symptom Onset ◽  
Clinical Characteristics ◽  
Symptom Duration ◽  
Test Results ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Antibody Tests ◽  
Pcr Test

Background Studies of outpatients with mild or moderate COVID-19 are uncommon. We studied: 1) association of symptoms with reverse transcriptase polymerase chain reaction (RT-PCR) test results; and 2) association of initial RT-PCR cycle threshold (Ct) in relation to duration of RT-PCR positivity in outpatients with mild or moderate COVID-19. Methods This was a cohort study of outpatients with confirmed COVID-19 and at least one symptom. Participants had repeat nasopharyngeal swabs and symptom checklists every 3–5 days until two consecutive RT-PCR tests were negative. RT-PCR tests were used to assess viral load. Antibody tests for COVID-19 were performed at 2 weeks, 4 weeks, and 8 weeks after symptom onset. Results Twenty-five patients (nine females) were enrolled, ranging in age from 19–58 (median age 28 years). All patients reported at least one symptom, with a median of six symptoms per patient. Symptoms persisted for 6–67 days (median duration 18 days). In all 25 patients, blood samples collected a median of 13 days after symptom onset were positive for SARS-CoV-2 antibodies in 15 (60%). After a median of 28 days following symptom onset, 23/23 patients with available samples tested positive for antibodies. The longest duration of positive RT-PCR test was 49 days from first positive PCR test (Mean = 27.4, SD = 12.5, Median = 24). Initial Ct was significantly associated with longer duration (β = -1.3, SE = 0.3, p<0.01 per 1 cycle higher) of RT-PCR positivity. Conclusions In mildly or moderately ill COVID-19 outpatients, RT-PCT tests remained positive for as long as 49 days and test positivity and symptom duration correlated with initial viral load.

Death and COVID-19 Anxiety in Home-Quarantined Individuals Aged 65 and Over During the Pandemic

2021 ◽  
pp. 003022282110598
Author(s):  
Hümeyra Aslaner ◽  
Betül Özen ◽  
Zeliha K. Erten ◽  
Mebrure Beyza Gökçek
Keyword(s):  
Polymerase Chain Reaction ◽  
Death Anxiety ◽  
Short Form ◽  
Anxiety Score ◽  
Test Results ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Test Result ◽  
Pcr Test

Urgent measures were taken for those at the age of 65 and over who were at the risk group all over the world due to the COVID-19 pandemic. It is known that many individuals at the age of 65 and over have experienced anxiety due to the uncertainties. This study aimed to determine the anxiety and death anxiety in individuals aged 65 and over who were isolation at home due to being diagnosed with COVID-19 or being in contact during the pandemic process. The study is descriptive and cross-sectional. It was performed with 656 home-quarantined individuals aged between 65–80 years with positive or negative real-time polymerase chain reaction (RT-PCR) test result. A form including questions about the death anxiety and the Coronavirus Anxiety Scale Short Form prepared by the researchers were administered to the individuals by phone call. Of the participants, 49.5% were male. Median COVID-19 anxiety score was 4 (0–18). Anxiety scores of the male and female participants were similar. Participants with negative polymerase chain reaction (PCR) results and those with death anxiety had higher COVID anxiety scores. Death anxiety has increased by 1.661 times in male gender, 1.983 times in RT-PCR positivity and 0.146 times in the presence of symptoms. Individuals with positive COVID-19 test results or those aged 65 and over who had death anxiety and negative COVID-19 test result but who were in home-isolation due to being a contact had higher anxiety score. For this reason, those with death anxiety can be supported in line with their religious beliefs to reduce anxiety. Those with negative PCR test results in quarantine can be adequately informed about the COVID-19.

scholarly journals No evidence of Re-infection or Human-to-Human Transmission in Cured COVID-19 Patients, a Retrospective Cohort Study

2020 ◽  
Author(s):  
Gang Xu ◽  
Feng Liu ◽  
Jun Zhao ◽  
Min Ye ◽  
Congrui Feng ◽  
...  
Keyword(s):  
Close Contact ◽  
Antibody Test ◽  
Test Results ◽  
Chain Reaction ◽  
Pcr Assay ◽  
Factors Associated ◽  
Polymerase Chain ◽  
Antibody Tests ◽  
Positive Results ◽  
Pcr Test

Abstract Objective: To clarify the clinical features of cured patients with coronavirus disease (COVID-19) and the relevance of IgM and IgG testing.Methods: A total of 187 cured COVID-19 patients with antibody test were followed up every two weeks at Guangzhou Eighth People's hospital. Assessment for general condition, symptoms, epidemiological contact history, polymerase chain reaction (PCR) assay, and antibody tests were performed and recorded. Information from Guangzhou CDC was also screened.Results: There were 154 (82.4%) patients with positive results for IgG and 35 (18.7%) patients with positive results for IgM. PCR assay was positive in 10 (5.3%) patients. Neither IgG nor IgM results showed a relationship with PCR test results (all P > 0.05). No re-infection was found in the cured patients. Among people who were in close contact with the cured patients, no one was diagnosed with COVID-19 as reported both by the cured patients and the Guangzhou CDC. Factors associated with appearance of IgG comprised hospitalization days (OR: 1.07, 95%CI: 1.02-1.13, P = 0.004) and antibiotics treatment (OR: 2.78, 95%CI: 1.10-7.01, P = 0.031) .Conclusion: In our study, neither re-infection nor human-to-human transmission was found in cured patients with COVID-19. Additionally, neither IgG nor IgM can be used to replace the PCR test in cured patients.

scholarly journals The Issue of Recurrently Positive Patients Who Recovered From COVID-19 According to the Current Discharge Criteria: Investigation of Patients from Multiple Medical Institutions in Wuhan, China

2020 ◽  
Vol 222 (11) ◽  
pp. 1784-1788 ◽  
Author(s):  
You Zou ◽  
Bin-Ru Wang ◽  
Liu Sun ◽  
Shan Xu ◽  
Yong-Gang Kong ◽  
...  
Keyword(s):  
Test Results ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Current Discharge ◽  
Negative Results ◽  
Medical Institutions ◽  
Polymerase Chain ◽  
Discharge Criteria ◽  
Test Result ◽  
Pcr Test

Abstract The current discharge criteria for COVID-19 require that patients have 2 consecutive negative results for reverse transcription polymerase chain reaction (RT-PCR) detection. Here, we observed that recurrent positive RT-PCR test results in patients with 3 consecutive negative results (5.4%) were significantly decreased compared with those in patients with 2 consecutive negative results (20.6%); such patients reported positive RT-PCR test results within 1 to 12 days after meeting the discharge criteria. These results confirmed that many recovered patients could show a positive RT-PCR test result, and most of these patients could be identified by an additional RT-PCR test prior to discharge.

scholarly journals Time variation in the probability of failing to detect a case of polymerase chain reaction testing for SARS-CoV-2 as estimated from a viral dynamics model

2021 ◽  
Vol 18 (177) ◽  
Author(s):  
Keisuke Ejima ◽  
Kwang Su Kim ◽  
Shoya Iwanami ◽  
Yasuhisa Fujita ◽  
Ming Li ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Viral Load ◽  
Symptom Onset ◽  
High Sensitivity ◽  
Viral Dynamics ◽  
Dynamics Model ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Pcr Test ◽  
Over Time

Viral tests including polymerase chain reaction (PCR) tests are recommended to diagnose COVID-19 infection during the acute phase of infection. A test should have high sensitivity; however, the sensitivity of the PCR test is highly influenced by viral load, which changes over time. Because it is difficult to collect data before the onset of symptoms, the current literature on the sensitivity of the PCR test before symptom onset is limited. In this study, we used a viral dynamics model to track the probability of failing to detect a case of PCR testing over time, including the presymptomatic period. The model was parametrized by using longitudinal viral load data collected from 30 hospitalized patients. The probability of failing to detect a case decreased toward symptom onset, and the lowest probability was observed 2 days after symptom onset and increased afterwards. The probability on the day of symptom onset was 1.0% (95% CI: 0.5 to 1.9) and that 2 days before symptom onset was 60.2% (95% CI: 57.1 to 63.2). Our study suggests that the diagnosis of COVID-19 by PCR testing should be done carefully, especially when the test is performed before or way after symptom onset. Further study is needed of patient groups with potentially different viral dynamics, such as asymptomatic cases.

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.

scholarly journals Effectiveness of BNT162b2 and mRNA-1273 covid-19 vaccines against symptomatic SARS-CoV-2 infection and severe covid-19 outcomes in Ontario, Canada: test negative design study

BMJ ◽  
2021 ◽  
pp. n1943 ◽  
Author(s):  
Hannah Chung ◽  
Siyi He ◽  
Sharifa Nasreen ◽  
Maria E Sundaram ◽  
Sarah A Buchan ◽  
...  
Keyword(s):  
Hospital Admission ◽  
Clinical Characteristics ◽  
Hospital Admissions ◽  
Vaccine Effectiveness ◽  
Community Dwelling ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Design Study ◽  
Symptomatic Infection ◽  
Polymerase Chain

AbstractObjectiveTo estimate the effectiveness of mRNA covid-19 vaccines against symptomatic infection and severe outcomes (hospital admission or death).DesignTest negative design study.SettingOntario, Canada between 14 December 2020 and 19 April 2021.Participants324 033 community dwelling people aged ≥16 years who had symptoms of covid-19 and were tested for SARS-CoV-2.InterventionsBNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine.Main outcome measuresLaboratory confirmed SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR) and hospital admissions and deaths associated with SARS-CoV-2 infection. Multivariable logistic regression was adjusted for personal and clinical characteristics associated with SARS-CoV-2 and vaccine receipt to estimate vaccine effectiveness against symptomatic infection and severe outcomes.ResultsOf 324 033 people with symptoms, 53 270 (16.4%) were positive for SARS-CoV-2 and 21 272 (6.6%) received at least one dose of vaccine. Among participants who tested positive, 2479 (4.7%) were admitted to hospital or died. Vaccine effectiveness against symptomatic infection observed ≥14 days after one dose was 60% (95% confidence interval 57% to 64%), increasing from 48% (41% to 54%) at 14-20 days after one dose to 71% (63% to 78%) at 35-41 days. Vaccine effectiveness observed ≥7 days after two doses was 91% (89% to 93%). Vaccine effectiveness against hospital admission or death observed ≥14 days after one dose was 70% (60% to 77%), increasing from 62% (44% to 75%) at 14-20 days to 91% (73% to 97%) at ≥35 days, whereas vaccine effectiveness observed ≥7 days after two doses was 98% (88% to 100%). For adults aged ≥70 years, vaccine effectiveness estimates were observed to be lower for intervals shortly after one dose but were comparable to those for younger people for all intervals after 28 days. After two doses, high vaccine effectiveness was observed against variants with the E484K mutation.ConclusionsTwo doses of mRNA covid-19 vaccines were observed to be highly effective against symptomatic infection and severe outcomes. Vaccine effectiveness of one dose was observed to be lower, particularly for older adults shortly after the first dose.

scholarly journals Evaluating the bacterial culture technique by Polymerase chain reaction for the diagnosis of Brucella abortus in milk of cows suspected with brucellosis.

2016 ◽  
Vol 40 (1) ◽  
pp. 5-8
Author(s):  
Bashar Sadeq Noomy
Keyword(s):  
Polymerase Chain Reaction ◽  
Brucella Abortus ◽  
Bacterial Culture ◽  
Culture Technique ◽  
Test Results ◽  
Chain Reaction ◽  
Culture Techniques ◽  
Milk Samples ◽  
Polymerase Chain ◽  
Pcr Test

      The aim of this study is to determine the sensitivity of bacterial culture technique in the detection of Brucella abortus in milk samples of aborted cows. Sixty samples of milk were collected from aborted cows during a period which did not exceed two months after the abortion. All of them were positive for rose bengal test. Results showed that Brucella abortus was isolated from 7 out of 60 (11.6%) from the milk of aborted cows, while PCR test showed that 32 out of 60 (53.3%) milk sample contained Brucella abortus. The specificity of culture techniques was 10%, but its sensitivity was only 21.8%. Beside the cautions in dealing with live Brucella abortus (as culture), it is also less sensitive than PCR, though it is better to use PCR technique in the diagnosis of brucellosis in aborted cows milk.

scholarly journals Descriptive epidemiology of coronavirus disease 2019 in Nigeria, 27 February–6 June 2020

2020 ◽  
Vol 148 ◽  
Author(s):  
K. O. Elimian ◽  
C. L. Ochu ◽  
E. Ilori ◽  
J. Oladejo ◽  
E. Igumbor ◽  
...  
Keyword(s):  
Health Planning ◽  
Case Fatality ◽  
National Surveillance ◽  
Descriptive Epidemiology ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Response Strategies ◽  
Polymerase Chain ◽  
Insight Into ◽  
Pcr Test

Abstract The objective of this study was to describe the epidemiology of COVID-19 in Nigeria with a view of generating evidence to enhance planning and response strategies. A national surveillance dataset between 27 February and 6 June 2020 was retrospectively analysed, with confirmatory testing for COVID-19 done by real-time polymerase chain reaction (RT-PCR). The primary outcomes were cumulative incidence (CI) and case fatality (CF). A total of 40 926 persons (67% of total 60 839) had complete records of RT-PCR test across 35 states and the Federal Capital Territory, 12 289 (30.0%) of whom were confirmed COVID-19 cases. Of those confirmed cases, 3467 (28.2%) had complete records of clinical outcome (alive or dead), 342 (9.9%) of which died. The overall CI and CF were 5.6 per 100 000 population and 2.8%, respectively. The highest proportion of COVID-19 cases and deaths were recorded in persons aged 31–40 years (25.5%) and 61–70 years (26.6%), respectively; and males accounted for a higher proportion of confirmed cases (65.8%) and deaths (79.0%). Sixty-six per cent of confirmed COVID-19 cases were asymptomatic at diagnosis. In conclusion, this paper has provided an insight into the early epidemiology of COVID-19 in Nigeria, which could be useful for contextualising public health planning.

scholarly journals Viral RNA Shedding and Transmission Potential of Asymptomatic and Pauci-symptomatic COVID-19 Patients

2020 ◽  
Author(s):  
Arghadip Samaddar ◽  
Ravisekhar Gadepalli ◽  
Vijaya Lakshmi Nag ◽  
Sanjeev Misra ◽  
Pankaj Bhardwaj ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Reverse Transcription ◽  
Viral Rna ◽  
Exhaled Breath ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Transmission Potential ◽  
Polymerase Chain ◽  
Pcr Test

Abstract We studied the pattern and duration of viral RNA shedding in 32 asymptomatic and 11 pauci-symptomatic coronavirus disease 2019 (COVID-19) cases. Viral RNA shedding in exhaled breath progressively diminished and became negative after six days of a positive reverse transcription polymerase chain reaction (RT-PCR) test. Therefore, the duration of isolation can be minimised to six days.

scholarly journals Perspective of Arguments in Public Health

2021 ◽  
Vol 9 (1) ◽  
pp. 44-45
Author(s):  
Dinesh Kumar
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Respiratory Symptoms ◽  
False Negative ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Negative Report ◽  
Polymerase Chain ◽  
Time Of Admission ◽  
Pcr Test

Recently, an argument was put forth because a symptomatic and positive patient for CoVID-19 turned tested negative after 7 days, so discharged from the hospital. Both at the time of admission and discharge real-time reverse transcriptase Polymerase Chain Reaction (RT-PCR) was done for testing of CoVID-19. Immediately, patient again developed respiratory symptoms and was admitted to hospital again. Amidst of current CoVID-19 pandemic, a question was asked “What is the specificity of the Real Time-Polymerase Chain Reaction (RT-PCR) test for COVID-19?” with an assumption that what if at the time of discharge the disease is present in patient but test turned out to be negative? In response to that a counter statement was posed that “It is the sensitivity that should be asked rather than specificity”. It was based on the implication of primary question that was implying false negative report of the RT-PCR. It means, since patient was discharged with negative result that could be false negative.

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