scholarly journals Diagnostic accuracy of rapid antigen tests in asymptomatic and presymptomatic close contacts of individuals with confirmed SARS-CoV-2 infection: cross sectional study

BMJ ◽  
2021 ◽  
pp. n1676
Author(s):  
Ewoud Schuit ◽  
Irene K Veldhuijzen ◽  
Roderick P Venekamp ◽  
Wouter van den Bijllaardt ◽  
Suzan D Pas ◽  
...  
Keyword(s):  
Viral Load ◽  
Cross Sectional Study ◽  
Antigen Test ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Predictive Values ◽  
Test Sensitivity ◽  
Antigen Tests ◽  
Close Contacts

Abstract Objective To assess the diagnostic test accuracy of two rapid antigen tests in asymptomatic and presymptomatic close contacts of people with SARS-CoV-2 infection on day 5 after exposure. Design Prospective cross sectional study. Setting Four public health service covid-19 test sites in the Netherlands. Participants 4274 consecutively included close contacts (identified through test-and-trace programme or contact tracing app) aged 16 years or older and asymptomatic for covid-19 when requesting a test. Main outcome measures Sensitivity, specificity, and positive and negative predictive values of Veritor System (Beckton Dickinson) and Biosensor (Roche Diagnostics) rapid antigen tests, with reverse-transcriptase polymerase chain reaction (RT-PCR) testing as reference standard. The viral load cut-off above which 95% of people with a positive RT-PCR test result were virus culture positive was used as a proxy of infectiousness. Results Of 2678 participants tested with Veritor, 233 (8.7%) had a RT-PCR confirmed SARS-CoV-2 infection of whom 149 were also detected by the rapid antigen test (sensitivity 63.9%, 95% confidence interval 57.4% to 70.1%). Of 1596 participants tested with Biosensor, 132 (8.3%) had a RT-PCR confirmed SARS-CoV-2 infection of whom 83 were detected by the rapid antigen test (sensitivity 62.9%, 54.0% to 71.1%). In those who were still asymptomatic at the time of sampling, sensitivity was 58.7% (51.1% to 66.0%) for Veritor (n=2317) and 59.4% (49.2% to 69.1%) for Biosensor (n=1414), and in those who developed symptoms were 84.2% (68.7% to 94.0%; n=219) for Veritor and 73.3% (54.1% to 87.7%; n=158) for Biosensor. When a viral load cut-off was applied for infectiouness (≥5.2 log10 SARS-CoV-2 E gene copies/mL), the overall sensitivity was 90.1% (84.2% to 94.4%) for Veritor and 86.8% (78.1% to 93.0%) for Biosensor, and 88.1% (80.5% to 93.5%) for Veritor and 85.1% (74.3% to 92.6%) for Biosensor, among those who remained asymptomatic throughout. Specificities were >99%, and positive and negative predictive values were >90% and >95%, for both rapid antigen tests in all analyses. Conclusions The sensitivities of both rapid antigen tests in asymptomatic and presymptomatic close contacts tested on day 5 onwards after close contact with an index case were more than 60%, increasing to more than 85% after a viral load cut-off was applied as a proxy for infectiousness.

scholarly journals Diagnostic accuracy of three prevailing rapid antigen tests for detection of SARS-CoV-2 infection in the general population: cross sectional study

2021 ◽  
Author(s):  
Roderick P Venekamp ◽  
Irene K Veldhuijzen ◽  
Karel GM Moons ◽  
Wouter van den Bijllaardt ◽  
Suzan D Pas ◽  
...  
Keyword(s):  
Viral Load ◽  
Diagnostic Accuracy ◽  
False Negative ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Predictive Values ◽  
Routine Sampling ◽  
Antigen Tests

Objective To assess the diagnostic accuracy of three rapid antigen tests (Ag-RDTs) for detecting SARS-CoV-2 infection in the general population. Design Cross-sectional study with follow-up using pseudonymised record linkage. Setting Three Dutch public health service COVID-19 test sites. Participants Consecutively included individuals aged 16 years and older presenting for SARS-CoV-2 testing. Main outcome measures Sensitivity, specificity, positive and negative predictive values of BD-Veritortm System (Becton Dickinson), PanBio (Abbott), and SD-Biosensor (Roche Diagnostics), applying routinely used sampling methods (combined oropharyngeal and nasal [OP-N] or nasopharyngeal [NP] swab), with molecular testing as reference standard. For SDBiosensor, the diagnostic accuracy with OP-N sampling was also assessed. A viral load cutoff (≥5.2 log10 SARS-CoV-2 E-gene copies/mL) served as a proxy of infectiousness. Results SARS-CoV-2 prevalence and overall sensitivities with 95% confidence intervals were 188/1441 (13.0%) and 129/188 (68.6% [61.5%-75.2%]) for BD-Veritor, 173/2056 (8.4%) and 119/173 (68.8% [61.3%-75.6%]) for PanBio, and 215/1769 (12.2%) and 160/215 (74.4% [68.0%-80.1%]) for SD-Biosensor with routine sampling, and 164/1689 (9.7%) and 123/164 (75.0% [67.7%-81.4%]) for SD-Biosensor with OP-N sampling. In those symptomatic or asymptomatic at sampling, sensitivities were 72.2%-83.4% and 54.0%-55.9%, respectively. With a viral load cut-off, sensitivities were 125/146 (85.6% [78.9%-90.9%]) for BD-Veritor, 108/121 (89.3% [82.3%-94.2%]) for PanBio, 160/182 (87.9% [82.3%-92.3%]) for SD-Biosensor with routine sampling, and 118/141 (83.7% [76.5%-89.4%]) with OP-N sampling. Specificities were >99%, and positive and negative predictive values >95%, for all tests in most analyses. 61.3% of false negative Ag-RDT participants returned for testing within 14 days (median of 3 days, interquartile range 3) of whom 90.3% tested positive. Conclusions The overall sensitivities of the three Ag-RDTs were 68.6%-75.0%, increasing to at least 85.6% after the viral load cut-off was applied. For SD-Biosensor, the diagnostic accuracy with OP-N and NP sampling was comparable. Over 55% of false negative Ag-RDT participants tested positive during follow-up.

scholarly journals Integration of symptomatic, demographical and diet-related comorbidities data with SARS-CoV-2 antibody rapid diagnostic tests during epidemiological surveillance: a cross-sectional study in Jakarta, Indonesia

BMJ Open ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. e047763
Author(s):  
Rina Agustina ◽  
Ari Fahrial Syam ◽  
Fadila Wirawan ◽  
Indah S Widyahening ◽  
Ahmad Jabir Rahyussalim ◽  
...  
Keyword(s):  
Predictive Value ◽  
Diagnostic Tests ◽  
Cross Sectional Study ◽  
Rapid Diagnostic Tests ◽  
Epidemiological Surveillance ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Predictive Values ◽  
Current Infection

ObjectivesAffordable options for COVID-19 epidemiological surveillance are needed. Virus detection by reverse transcription-PCR (RT-PCR) is sensitive but costly, and antigen-based rapid diagnostic tests (RDTs) are cheap but with reduced sensitivity; both detect current infection but not exposure. RDT-IgM/IgG antibodies to SARS-CoV-2 detect exposure but have poor sensitivity for current infection. We investigated if the integration of symptomatic, demographical and diet-related comorbidities data with antibody RDTs improves their potential to assess infection rates in addition to exposure, thereby broadening their utility for surveillance.DesignWe conducted a cross-sectional study using data from community surveillance for SARS-CoV-2. Health workers collected nasopharyngeal swabs for RT-PCR and RDT antigen assessments and venous blood for RDT-IgM/IgG from symptomatic and asymptomatic persons. Data on age, gender, contact history, symptoms (ie, fever, cough, runny nose, sore throat, headache, dyspnoea and diarrhoea), diet-related comorbidities (ie, diabetes and hypertension) and chest radiology were collected.SettingHigh-risk communities in Jakarta, Indonesia, in May 2020.Participants343 community members’ data were included.Outcome measuresRDT-IgM/IgG sensitivity, specificity and predictive values and area under receiver operating characteristic curve for RT-PCR positivity using RDT results alone and in combination with other predictors, including symptom components derived from principal component analysis.ResultsThere were 24 PCR-confirmed infections. RDT-IgM/IgG-positive tests were associated with infection (OR 10.8, 95% CI 4.43 to 26.4, p<0.001) with an area under the curve (AUC) of 0.708% and 50% sensitivity, 91.5% specificity, 30.8% positive predictive value (PPV) and 96.1% negative predictive value (NPV). RDT results combined with age, gender, contact history, symptoms and comorbidities increased the AUC to 0.787 and yielded 62.5% sensitivity, 87.0% specificity, 26.6% PPV and 96.9% NPV.ConclusionsSARS-CoV-2 RDT-IgM/IgG results integrated with other predictors may be an affordable tool for epidemiological surveillance for population-based COVID-19 exposure and current infection, especially in groups with outbreaks or high transmission.

scholarly journals Diagnostic accuracy of rapid antigen tests in pre-/asymptomatic close contacts of individuals with a confirmed SARS-CoV-2 infection

2021 ◽  
Author(s):  
E Schuit ◽  
IK Veldhuijzen ◽  
RP Venekamp ◽  
W van den Bijllaardt ◽  
SD Pas ◽  
...  
Keyword(s):  
Viral Load ◽  
Diagnostic Accuracy ◽  
Contact Tracing ◽  
Test Accuracy ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Gene Copies ◽  
Registration Number ◽  
Antigen Tests ◽  
Close Contacts

AbstractBackgroundPre-/asymptomatic close contacts of SARS-CoV-2 infected individuals were tested at day 5 after contact by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Diagnostic accuracy of antigen-detecting rapid diagnostic tests (Ag-RDT) in pre-/asymptomatic close contacts was up till now unknown.MethodsWe performed a prospective cross-sectional diagnostic test accuracy study. Close contacts (e.g. selected via the test-and-trace program or contact tracing app) aged ≥16 years and asymptomatic when requesting a test, were included consecutively and tested at day 5 at four Dutch public health service test sites. We evaluated two Ag-RDTs (BD Veritor™ System Ag-RDT (BD), and Roche/SD Biosensor Ag-RDT (SD-B)) with RT-PCR as the reference standard. Virus culture was performed in RT-PCR positive individuals to determine the viral load cut-off above which 95% was culture positive, as a proxy of infectiousness.ResultsOf 2,678 BD-tested individuals, 233 (8.7%) were RT-PCR positive and BD detected 149 (sensitivity 63.9%; 95% confidence interval 57.4%-70.1%). Out of 1,596 SD-B-tested individuals, 132 (8.3%) were RT-PCR positive and SD-B detected 83 (sensitivity 62.9%; 54.0%-71.1%). When applying an infectiousness viral load cut-off ≥ 5.2 log10 gene copies/mL, the sensitivity was 90.1% (84.2%-94.4%) for BD, 86.8% (78.1% to 93.0%) for SD-B overall, and 88.1% (80.5%-93.5%) for BD, 85.1% (74.3%-92.6%) for SD-B for those still asymptomatic at the actual time of sampling. Specificity was >99% for both Ag-RDTs in all analyses.ConclusionsThe sensitivity for detecting SARS-CoV-2 of both Ag-RDTs in pre-/asymptomatic close contacts is over 60%, increasing to over 85% after applying an infectiousness viral load cut-off.Trial registration numberNot applicable. A study protocol is available upon request.

Factors associated with HIV care and treatment cascade in Rio Grande do Sul, Brazil, 2014–2017: A cross-sectional study

2021 ◽  
pp. 095646242097594
Author(s):  
Guilherme B Shimocomaqui ◽  
Craig S Meyer ◽  
Maria L Ikeda ◽  
Elson Romeu Farias ◽  
Tonantzin R Gonçalves ◽  
...  
Keyword(s):  
Viral Load ◽  
Rio Grande ◽  
Undetectable Viral Load ◽  
Cross Sectional Study ◽  
Hiv Care ◽  
Rio Grande Do Sul ◽  
Sectional Study ◽  
Cross Sectional ◽  
Treatment Cascade ◽  
Care And Treatment

In 2018, Rio Grande do Sul (RS) had some of the highest HIV/AIDS rates in Brazil, and we did not find any studies about the HIV care and treatment cascade (HCTC) related to this state. We aimed to estimate the indicators of HCTC of RS, Brazil, and associated factors. A cross-sectional study with all people living with HIV (PLWH) in RS between 1 January 2014 and 31 December 2017 was conducted using a national database which registers all HIV notifications, CD4 and viral load laboratory data and antiretroviral therapy (ART) usage in the public health system. We considered sex, age, education, race, year of HIV diagnosis, and health region as predictor factors, and defined linkage to care, retention to care, being on ART, and having undetectable viral load as the HCTC indicators. Descriptive analysis and multivariable logistic regression were performed using Stata 15.2. A total of 116,121 PLWH were diagnosed, 79,959 were linked to care, 72,117 retained in care, 69,219 on ART, and 54,857 had undetectable viral load from 2014 to 2017. We observed greatest attrition for younger age, non-white, and lower education in all HCTC indicators. Women are more likely to have undetectable viral load (OR = 1.04, 95% CI: 1.01–1.07), even though they are less likely to be retained to care (OR = 0.92; 95% CI: 0.89–0.96) and on ART (OR = 0.82; 95% CI: 0.78–0.86). Although all HCTC indicators have increased over the period and the “test and treat” policy indicates improvements in ART and in undetectable viral load outcomes, evidence suggests specific attrition and disparities such as those related to HIV healthcare facilities should be addressed. These findings may be used by researchers, health professionals, and policymakers in order to investigate and implement interventions to better engage PLWH across the HCTC.

scholarly journals Liver ultrasound elastography for the evaluation of periportal fibrosis in schistosomiasis mansoni: A cross-sectional study

2018 ◽  
Author(s):  
Joelma Carvalho Santos ◽  
Andrea Dória Batista ◽  
Carla Maria Mola Vasconcelos ◽  
Roberto Souza Lemos ◽  
Valter Romão de Souza ◽  
...  
Keyword(s):  
Shear Wave ◽  
Shear Wave Elastography ◽  
Cross Sectional Study ◽  
Cutoff Point ◽  
Sectional Study ◽  
Cross Sectional ◽  
Predictive Values ◽  
Cutoff Value ◽  
Periportal Fibrosis ◽  
Schistosomiasis Mansoni

AbstractBackgroundARFI elastrography has been used as a noninvasive method to assess the severity of liver fibrosis in viral hepatitis, although with few studies in schistosomiasis mansoni. We aimed to evaluate the performance of point shear wave elastography (pSWE) for predicting significant periportal fibrosis (PPF) in schistosomotic patients and to determine its best cutoff point.Methodology/Principal findingsThis cross-sectional study included 358 adult schistosomotic patients subjected to US and pSWE on the right lobe. Two hundred two patients (62.0%) were women, with a median age of 54 (ranging 18-92) years. The pSWE measurements were compared to the US patterns of PPF, as gold standard, according to the Niamey classification. The performance of pSWE was calculated as the area under the ROC curve (AUC). Patients were further classified into two groups: 86 patients with mild PPF and 272 patients with significant PPF. The median pSWE of the significant fibrosis group was higher (1.40 m/s) than that of mild fibrosis group (1.14 m/s, p<0.001). AUC was 0.719 with ≤1.11 m/s as the best cutoff value for excluding significant PPF. Sensitivity and negative predictive values were 80.5% and 40.5%, respectively. Whereas, for confirming significant PPF, the best cutoff value was >1.39 m/s, with specificity of 86.1% and positive predictive value of 92.0%.Conclusions/SignificancepSWE was able to differentiate significant from mild PPF, with better performance to predict significant PPF.Author summaryIn the developing world, over 207 million people are infected with parasitic Schistosoma worms. Among the species of Schistosoma that infect humans Schistosoma mansoni is one of the most common causes of illness. Here, we investigated the performance of point shear wave elastography (pSWE) for predicting significant periportal fibrosis (PPF) in schistosomotic patients and to determine its best cutoff point. We examined 358 people from northeast of Brazil for Schistosoma infections. The present study showed that pSWE was able to differentiate significant from mild PPF, with better performance to predict significant PPF.

scholarly journals Sources of psychological distress among primary care physicians during the COVID-19 pandemic’s first wave in Spain: a cross-sectional study

2021 ◽  
Vol 22 ◽  
Author(s):  
Ana Cebrián-Cuenca ◽  
José Joaquín Mira ◽  
Elena Caride-Miana ◽  
Antonio Fernández-Jiménez ◽  
Domingo Orozco-Beltrán
Keyword(s):  
Primary Care ◽  
Psychological Distress ◽  
Primary Care Physicians ◽  
Linear Regression Analysis ◽  
Cross Sectional Study ◽  
Multivariate Linear Regression Analysis ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Protective Measures

Abstract Background: The COVID-19 pandemic is affecting people worldwide. In Spain, the first wave was especially severe. Objectives: This study aimed to identify sources and levels of distress among Spanish primary care physicians (PCPs) during the first wave of the pandemic (April 2020). Methods: A cross-sectional study was conducted using a survey that included sociodemographic data, a description of working conditions related to distress [such as gaps in training in protective measures, cleaning, and hygiene procedures in work setting, unavailability of personal protective equipments (PPEs) and COVID-19 RT-PCR test, and lack of staff due to be infected] and a validated scale, the ‘Self-applied Acute Stress Scale’ (EASE). The survey was answered by a non-probability sampling of PCPs working in family healthcare centres from different regions of Spain. Analysis of variance and multivariate linear regression analysis were performed. Results: In all, out of 518 PCP participants, 123 (23.7%) obtained high psychological distress scores. Only half of them had received information about the appropriate use of PPE. PCP characteristics associated with higher levels of distress include female gender [1.69; 95% confidence interval (CI) 0.54, 2.84]; lack of training in protective measures (1.96; 95% CI 0.94, 2.99); unavailable COVID-19 RT-PCR for health care workers after quarantine or COVID-19 treatment (−0.77 (−1.52, −0.02). Reinforcing disinfection of the work environment (P < 0.05), availability of PPEs (P < 0.05), and no healthcare professional was infected (P < 0.05) were related to the lowest distress score. Conclusions: A better understanding of the sources of distress among PCPs could prevent its effect on future outbreaks.

scholarly journals Molecular study of sapovirus in acute gastroenteritis in children: a cross-sectional study

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 123
Author(s):  
Maysaa El Sayed Zaki ◽  
Raghdaa Shrief ◽  
Rasha H. Hassan
Keyword(s):  
Stool Sample ◽  
Acute Gastroenteritis ◽  
Rna Extraction ◽  
Winter Season ◽  
Molecular Study ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Presenting Symptoms

Background: Sapovirus has emerged as a viral cause of acute gastroenteritis. However, there are insufficient data about the presence of this virus among children with acute gastroenteritis. The present study aimed to evaluate the presence of sapovirus in children with acute gastroenteritis by reverse transcriptase-polymerase chain reaction (RT-PCR). Methods: A cross-sectional study enrolled 100 children patients with acute gastroenteritis from outpatient clinics with excluded bacterial pathogens and parasitic infestation. A stool sample was collected from each child for laboratory examination. Each stool sample was subjected to study by direct microscopic examination, study for rotavirus by enzyme-linked immunoassay (ELISA) and the remaining sample was subjected to RNA extraction and RT- PCR for sapovirus. Results: The most frequently detected virus was rotavirus by ELISA (25%). RT-PCR detected sapovirus in 7% of the stool samples. The children with sapovirus were all from rural regions and presented mainly during the winter season in Egypt (42.9%). The main presenting symptoms were fever (71.4%) and vomiting (57.1%). None of the children with sapovirus had dehydration. Rotavirus was significantly associated with sapovirus infections in 5 patients (71.4%, P=0.01). There was an insignificant difference between symptoms of gastroenteritis in children with sapovirus and children with gastroenteritis without sapovirus as regards vomiting (P=0.7), fever (P=0.46), and abdominal pain (P=0.69). Conclusion: The present study highlights the emergence of sapovirus as a frequent pathogen associated with acute gastroenteritis in children. There is a need for a national survey program for the study of sapovirus among other pathogens associated with acute gastroenteritis for better management of such infection.

Immunological and molecular detection of rotavirus genotype in calves with gastroenteritis in Diyala-Iraq

2021 ◽  
Vol 1 (1) ◽  
pp. 001-013
Author(s):  
Ammar Talib Nasser ◽  
Abdulrazak Shafiq Hasan ◽  
Amer Khazaal Saleh ◽  
Mohammad Kassem Saleh
Keyword(s):  
Molecular Detection ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Reverse Transcription Pcr ◽  
Group A ◽  
Stool Antigen ◽  
Stool Samples ◽  
Age Range

Aim: To explore the prevalence of rotavirus infection along with the molecular detection and genotyping of group A rotavirus (RVA) among bovine calves up to 5 months old in Diyala province-Iraq. Methods: This is a cross sectional study conducted in Diyala province-Iraq during the period of 2019-2020. One hundred bovine calves with age range of 1-5 months were included in the study. All were suffering acute gastroenteritis. Serum anti-rotavirus IgM and IgG plus fecal rotavirus Ag were tested for using ELISA techniques. Stool samples positive for rotavirus Ag were submitted for reverse transcription PCR (RT-PCR) for G and P genes, followed by sequencing and genotyping thereafter. Statistical analysis was done using SPSS version 25 and P values ≤ 0.05 were considered significant. Results: The positivity rate of anti-rotavirus IgM was 80% (P = 0.0001), and that of anti-rotavirus IgG was 79% (P = 0.0001). The rotavirus stool antigen was detected in 68% of calves (P = 0.01). A total of 45 stool samples which were positive for rotavirus Ag were submitted for RT-PCR; 13 (28.9%) were positive and 32 (71.1%) were negative (P = 0.084). 10 PCR positive samples were used for sequencing and genotyping and indicated that all investigated strains belonged to G1P[8] genotype. Conclusion: The current strains analyzed belonged to the G1P[8] RVA genotypes, affirming that employment of VP7 gene polymorphism accurately yielded uniform phylogenetic distances amongst investigated rotavirus strains and that there were no noticeable assortment events between human and animal rotavirus strains in Diyala province.

scholarly journals High levels of viral load monitoring and viral suppression under Treat All in Rwanda – a cross‐sectional study

2020 ◽  
Vol 23 (6) ◽  
Author(s):  
Jonathan Ross ◽  
Muhayimpundu Ribakare ◽  
Eric Remera ◽  
Gad Murenzi ◽  
Athanase Munyaneza ◽  
...  
Keyword(s):  
Viral Load ◽  
Viral Suppression ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Viral Load Monitoring ◽  
Load Monitoring ◽  
Treat All
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