scholarly journals Comparison of SARS-CoV-2 antigen electrochemiluminescence immunoassay to RT-PCR assay for laboratory diagnosis of COVID-19 in Peshawar

Diagnosis ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bilal Iqbal ◽  
Maria Khan ◽  
Noman Shah ◽  
Mirza Muhammad Dawood ◽  
Valeed Jehanzeb ◽  
...  

Abstract Objectives Antigen based rapid diagnostic tests possesses a potential to be utilized along with Gold standard methods to detect Covid-19 infection to cope with the demand of testing. The aim of this study was to determine diagnostic accuracy of electrochemiluminescence based automated antigen detection immunoassay comparing with molecular based test RT-PCR (Covid-19). Methods It was a cross-sectional study conducted in RMI Peshawar, from 1st April 2021 till 30th April 2021. The study comprised 170 individuals who were suspected of having Covid-19. Nasopharyngeal samples taken from suspected individuals were analyzed by RT-PCR and automated antigen test (Elecsys SARS-CoV-2 Antigen) simultaneously. The correlation of SARS-CoV-2 antigen with PCR positive and negative cases was analyzed for specificity, sensitivity respectively. Results The ECLIA based Elecsys antigen test (Roche) revealed overall sensitivity 72%, specificity 95% and accuracy of 94.9%. Sensitivity of antigen test progressively declined from 94.3% in Ct <25 to 70.8% in Ct 26–29 and then to 47.2% in Ct 30–35. Conclusions Based on the findings of our study we conclude that automated antigen testing (Elecsys SARS-CoV-2 Antigen) cannot replace molecular based testing like RT PCR. Elecsys SARS-CoV-2 Ag test should be used complementary to RT-PCR in testing algorithms. Frequent testing strategy should be adopted while using automated antigen testing to overcome its limitation in individuals with low viral loads.

2020 ◽  
Author(s):  
Abdulkarim Abdulrahman ◽  
Saad Mallah ◽  
Abdulla Ismael AlAwadhi ◽  
Simone Perna ◽  
Essam Janahi ◽  
...  

Introduction: Proactive prediction of the epidemiologic dynamics of viral diseases and outbreaks of the likes of COVID-19 has remained a difficult pursuit for scientists, public health researchers, and policymakers. It is unclear whether RT-PCR Cycle Threshold (Ct) values of COVID-19 (or any other virus) as indicator of viral load, could represent a possible predictor for underlying epidemiological changes on a population level. Objectives: To investigate whether population-wide changes in SARS-CoV-2 RT-PCR Ct values over time are associated with the daily fraction of positive COVID-19 tests. In addition, this study analyses the factors that could influence the RT-PCR Ct values. Method: A retrospective cross-sectional study was conducted on 63,879 patients from May 4, 2020 to September 30, 2020, in all COVID-19 facilities in the Kingdom of Bahrain. Data collected included number of tests and newly diagnosed cases, as well as Ct values, age, gender nationality, and symptomatic status. Results: Ct values were found to be negatively and very weakly correlated with the fraction of daily positive cases in the population r = -0.06 (CI95%: -0.06; -0.05; p=0.001). The R-squared for the regression model (adjusting for age and number of daily tests) showed an accuracy of 45.3%. Ct Values showed an association with nationality (p=0.012). After the stratification, the association between Ct values and the fraction of daily positive cases was only maintained for the female gender and Bahraini-nationality. Symptomatic presentation was significantly associated with lower Ct values (higher viral loads). Ct values do not show any correlation with age (p=0.333) or gender (p=0.522). Conclusion: We report one of the first and largest studies to investigate the epidemiological associations of Ct values with COVID-19. Ct values offer a potentially simple and widely accessible tool to predict and model epidemiological dynamics on a population level. More population studies and predictive models from global cohorts are necessary.


Author(s):  
Xian Zhang ◽  
Xuhui Chen ◽  
Liwen Chen ◽  
Chaohua Deng ◽  
Xiaojing Zou ◽  
...  

PurposeThe aim of this study was to identify whether SARS-COV-2 infected in ocular surface.MethodsCross-sectional study of patients presenting for who received a COVID-19 diagnosis, from December 30, 2019 to February 7, 2020, at Tongji hospital, Tongji medical college, Huazhong University of Science and Technology. Demographics, temperature was recorded, blood routine test (Rt), chest Computed Tomography (CT) were took intermittently, and SARS-COV-2 real-time reverse-transcriptase–polymerase-chain-reaction (RT-PCR) assay were arranged for the nasopharyngeal and conjunctival swab samples.ResultsA total of 102 patients (48 Male [50%] and 54 Female [50%]) with clinical symptoms, Rt, and chest Computed Tomography (CT) abnormalities were identified with a clinical diagnosis of COVID-19. Patients had a mean [SD] gestational age of 57.63 [14.90] years. Of a total of 102 patients identified, 72 patients (36 men [50%] and 36 women [50%]; mean [SD] age, 58.68 [14.81] years) confirmed by laboratory diagnosis with SARS-COV-2 RT-PCR assay. Only two patients (2.78%) with conjunctivitis was identified from 72 patients with a laboratory confirmed COVID-19. However, SARS-COV-2 RNA fragments was found in ocular discharges by SARS-COV-2 RT-PCR only in one patient with conjunctivitis.ConclusionsAlthough we suspect the incidence of SARS-COV-2 infection through the ocular surface is extremely low, the nosocomial infection of SARS-CoV-2 through the eyes after occupational exposure is a potential route. The inefficient diagnostic method and the sampling time lag may contribute to the lower positive rate of conjunctival swab samples of SARS-COV-2. Therefore, to lower the SARS-COV-2 nosocomial infection, the protective goggles should be wore in all the health care workers.


BMJ ◽  
2021 ◽  
pp. n1676
Author(s):  
Ewoud Schuit ◽  
Irene K Veldhuijzen ◽  
Roderick P Venekamp ◽  
Wouter van den Bijllaardt ◽  
Suzan D Pas ◽  
...  

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.


2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Ahmad Aliyu ◽  
Babatunde Adelekan ◽  
Nifarta Andrew ◽  
Eunice Ekong ◽  
Stephen Dapiap ◽  
...  

Abstract Background Expanded access to antiretroviral therapy (ART) leads to improved HIV/AIDS treatment outcomes in Nigeria, however, increasing rates of loss to follow-up among those on ART is threatening optimal standard achievement. Therefore, this retrospective cross-sectional study is aimed at identifying correlates and predictors of loss to follow-up in patients commencing ART in a large HIV program in Nigeria. Methods Records of all patients from 432 US CDC Presidents Emergency Plan for AIDS Relief (PEPFAR) supported facilities across 10 States and FCT who started ART from 2004 to 2017 were used for this study. Bivariate and multivariate analysis of the demographic and clinical parameters of all patients was conducted using STATA version 14 to determine correlates and predictors of loss to follow-up. Results Within the review period, 245,257 patients were ever enrolled on anti-retroviral therapy. 150,191 (61.2%) remained on treatment, 10,960 (4.5%) were transferred out to other facilities, 6926 (2.8%) died, 2139 (0.9%) self-terminated treatment and 75,041 (30.6%) had a loss to follow-up event captured. Males (OR: 1.16), Non-pregnant female (OR: 4.55), Patients on ≥ 3-monthly ARV refills (OR: 1.32), Patients with un-suppressed viral loads on ART (OR: 4.52), patients on adult 2nd line regimen (OR: 1.23) or pediatric on 1st line regimen (OR: 1.70) were significantly more likely to be lost to follow-up. Conclusion Despite increasing access to anti-retroviral therapy, loss to follow-up is still a challenge in the HIV program in Nigeria. Differentiated care approaches that will focus on males, non-pregnant females and paediatrics is encouraged. Reducing months of Anti-retroviral drug refill to less than 3 months is advocated for increased patient adherence.


2021 ◽  
Vol 9 (4) ◽  
pp. 798
Author(s):  
Giorgia Caruana ◽  
Antony Croxatto ◽  
Eleftheria Kampouri ◽  
Antonios Kritikos ◽  
Onya Opota ◽  
...  

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.


2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Umar Saeed ◽  
Sara Rizwan Uppal ◽  
Zahra Zahid Piracha ◽  
Azhar Rasheed ◽  
Zubair Aftab ◽  
...  

AbstractRapid diagnosis of SARS-CoV-2 during pandemic enables timely treatment and prevention of COVID-19. Evaluating the accuracy and reliability of rapid diagnostic testing kits is crucial for surveillance and diagnosis of SARS-CoV-2 infections in general population, injection drug users, multi-transfused populations, healthcare workers, prisoners, barbers and other high risk populations. The aim of this study was to evaluate performance and effectiveness of nasopharyngeal swab (NSP) and saliva based rapid antigen detection testing kits in comparison with USFDA approved triple target gold standard real-time polymerase chain reaction. A cross-sectional study was conducted on 33,000 COVID-19 suspected patients. From RT-PCR positive patients, nasopharyngeal swab (NSP) and saliva samples were obtained for evaluation of rapid COVID-19 testing kits (RDT). 100/33,000 (0.3%) of specimens were RT-PCR positive for SARS-CoV-2. Among RT-PCR positive, 62% were males, 34% were females, and 4% were children. The NSP-RDT (Lepu Medical China) analysis revealed 53% reactivity among males, 58% reactivity among females, and 25% reactivity among children. However saliva based RDT (Lepu Medical China) analysis showed 21% reactivity among males and 23% among females, and no reactivity in children. False negative results were significantly more pronounced in saliva based RDT as compared to NSP-RDT. The sensitivity of these NSP-RDT and saliva based RDT were 52% and 21% respectively. The RDTs evaluated in this study showed limited sensitivities in comparison to gold standard RT-PCR, indicating that there is a dire need in Pakistan for development of suitable testing to improve accurate COVID-19 diagnosis in line with national demands.


Author(s):  
Sebastián Videla ◽  
Aurema Otero ◽  
Sara Martí ◽  
M. Ángeles Domínguez ◽  
Nuria Fabrellas ◽  
...  

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in December 2019 and still is a major global health challenge. Lockdown measures and social distancing sparked a global shift towards online learning, which deeply impacted universities’ daily life, and the University of Barcelona (UB) was not an exception. Accordingly, we aimed to determine the impact of the SARS-CoV-2 pandemic at the UB. To that end, we performed a cross-sectional study on a sample of 2784 UB members (n = 52,529). Participants answered a brief, ad hoc, online epidemiological questionnaire and provided a nasal swab for reverse transcription polymerase chain reaction (RT-PCR) SARS-CoV-2 analysis and a venous blood sample for SARS-CoV-2 IgG antibody assay. Total prevalence of SARS-CoV-2 infection (positive RT-PCR or positive IgG) was 14.9% (95%CI 13.3 to 17.0%). Forty-four participants (1.6%, 95%CI: 1.2–2.1%) were positive for SARS-CoV-2 RT-PCR. IgG against SARS-CoV-2 was observed in 12.8% (95%CI: 11.6–14.1%) of participants. Overall, while waiting for population vaccination and/or increased herd immunity, we should concentrate on identifying and isolating new cases and their contacts.


Author(s):  
Thanh Xuan Nguyen

TÓM TẮT Đặt vấn đề: Bệnh COVID-19 đa dạng từ không có triệu chứng đến có các triệu chứng nhẹ cho đến viêm phổi nặng, hội chứng suy hô hấp cấp tiến triển (ARDS), nhiễm khuẩn huyết suy đa tạng và tử vong. Người cao tuổi, người có bệnh mạn tính sẽ có nguy cơ diễn biến nặng nhiều hơn. Nghiên cứu này nhằm xác định nồng độ lactate và PCT ở những bệnh nhân Covid-19 và xét mối liên quan giữa lactate và PCT trên bệnh nhân Covid-19. Đối tượng và phương pháp: Nghiên cứu mô tả cắt ngang trên 126 bệnh nhân được chẩn đoán nhiễm Sars-Cov-2 bằng xét nghiệm RT PCR. Kết quả: Tuổi trung bình 55,98 ± 17,1 tuổi (4 - 98 tuổi). Bệnh nhân > 60 tuổi chiếm tỉ lệ cao nhất (42,8%). Trung vị PCT: 3,6 (95%CI:3,21 - 3,75) ng/ml; trung vị lactate 1,5 (95%CI:1,21 - 1,91) mmol/L; lactate có tương quan thuận và yếu với procalcitonin với r = 0,241; p < 0,001. Nồng độ procalcitonin > 0,1 ng/ml; lactate > 2 mmol/l ở bệnh nhân Covid-19 chiếm tỷ lệ cao với 89,7% và 39,7%. Kết luận: Chỉ điểm procalcitonin, lactate tăng cao ở bệnh nhân Covid-19. ABSTRACT ASSESSMENT OF SERUM LEVEL OF LACTATE AND PROCALCITONIN IN COVID-19 PATIENTS Background: Sars-CoV-2 has been identified as the cause of acute respiratory infections in Wuhan city, Hubei province, China, and has since spread worldwide. Sars-CoV-2 is capable of aerosol transmission in enclosed, crowded, and poorly ventilated spaces. COVID-19 illness ranges from asymptomatic to mild symptoms to severe pneumonia, acute respiratory distress syndrome (ARDS), sepsis, multiple organ failure, and death. This study aims to determine lactate and PCT levels in Covid-19 patients and examine the relationship between lactate and PCT in Covid-19 patients. Methods: A cross-sectional study was performed on 126 patients diagnosed with Sars-Cov-2 infection by RT-PCR. Results: Mean age was 55.98 ± 17.1 years (range: 4-98 years). Patients more than 60 years old were accounted for the highest rate (42.8%). Median PCT: 3.6 (95%CI:3.21 - 3.75) ng/ml; median lactate 1.5 (95%CI:1.21 - 1,91) mmol/L; lactate has a positive and weak correlation with procalcitonin with r = 0.241; p < 0.001. Procalcitonin concentration > 0.1 ng/ml; lactate > 2 mmol/l in patients with Covid-19 accounted for a high rate with 89.7% and 39.7%. Conclusion: Serum level of procalcitonin and lactate raise highly in Covid-19 patients. Keywords: Covid-19, procalcitonin, lactate.


Author(s):  
Salah Tofik Jalal Balaky ◽  
Saeed Ghulam Hussain ◽  
Amer Ali Khaleel ◽  
Furat Tahseen Sabeer ◽  
Ahang Hasan Mawlood

Background & objectives: Introducing a nucleic acid test program is aimed to diagnose and reduces the risk of viral infection or transmission. DNA assay for HBV can detect infection in the windows period, chronic occult infection and can discriminate between active and inactive HBV infection. This cross-sectional study designed to diagnose, analyze HBV infection and to differentiate active from inactive infection based on viral DNA detection. Methods: Blood samples were collected from 256 patients previously diagnosed on the clinical ground as hepatitis B seropositive in Erbil Central Lab. The viral nucleic acid quantitative assessment was done for the collected samples using RT-PCR. Q-square was performed for statistical analysis. Results: Out of 256 collected blood samples 93 (36.3%) showed HBV-DNA positive titers above 50 IU/ml. Among positive subjects, 67 (72.04%) was categorized as inactive carriers (˂ 2000-20.000 IU/ml HBV-DNA titers). Conclusions: The data produced from this study confirmed the importance of the RT-PCR technique in sensitivity and reliability as a superior diagnostics tool specifically in differentiating active from inactive HBV carriers.


Author(s):  
Ana Cebrián-Cuenca ◽  
José Joaquín Mira ◽  
Elena Caride-Miana ◽  
Antonio Fernández-Jiménez ◽  
Domingo Orozco-Beltrán

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.


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