Who Is Immune Against COVID-19 and Safe to Return to Work: The Impact of Laboratory Assays (original) (raw)
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Egyptian journal of Immunology
COVID-19 pandemic is a substantial challenge for healthcare systems. Severe acute respiratory syndrome coronavirus (SARS-CoV-2) reverse transcription-polymerase chain reaction (RT-PCR) tests are considered the gold standard technique for diagnosis of symptomatic and asymptomatic infectious viral carriers and for screening special or at-risk populations. The pooled testing procedure is commonly used to reduce the cost of screening a large number of individuals for infectious diseases. This work was conducted to verify the accuracy of the standard SARS COV-2 RT- real-time PCR kit for detecting a single positive sample in a pool of negative samples. Kit verification using negative and positive samples was performed for the selection of the target pool sizes. RNA extracts from 443 healthcare workers, after 15 days’ rotation in EL-Raghy Isolation COVID-19 Hospital, Assiut University during the first outbreak of COVID-19 pandemic (the period from June to September 2020) were obtained and ...
GCISTEM Proceeding
Since early 2020, a novel coronavirus named SARS-CoV-2 is causing COVID-19 pandemic. This novel virus is very contagious as it spreads quickly, primarily via droplets during person-to-person contact. The gold standard method to confirm SARS-CoV-2 infection is the reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) assay, but this technology is labor-intensive and time-consuming. An effective, point-of-care assay will be required to screen the general population for SARS-CoV-2 infection, hence RT-qPCR assay could be used mainly to confirm suspected cases with COVID-19. In this cross-sectional study, we described our experiences in using the antibody and antigen rapid test devices to screen for SARS-CoV-2 infection among staff and students at Universitas Pelita Harapan, respectively. Firstly, we found that the participating staff who worked regularly at the academic premises were not infected by SARS-CoV-2 during November and December 2020, suggested by seronegative...
VirusDisease, 2020
The coronavirus disease 2019 (COVID-19) pandemic is caused by the severe acute respiratory syndrome coronavirus-2, a new member of the Coronavirus family. The virus was first identified in Wuhan, China, where the epidemic originated. The viral genome was sequenced and a real time reverse transcription polymerase chain reaction assay was developed and used for the detection of virus. Different countries took different approaches for the diagnosis of COVID-19. Some countries prioritized extensive testing for COVID-19 at a very early phase of the pandemic whereas other countries took a long time to build the testing capacity and to implement the testing extensively. The assay design formats were available in the public domain and thereby allowing researchers to replicate them to make diagnostic kits. Consequently, several antigen or antibody-based diagnostic tests were also developed for the diagnosis of COVID-19. However, there were some validation and regulatory challenges while bringing these assays into the market. During the course of the pandemic, it became clear that the countries which implemented testing at an early stage of the pandemic were capable of controlling the spread more effectively than those that implemented them at later stages. As several countries implemented a lockdown for controlling the spread of the virus, it is critical to build the testing capability to meet the extensive need of testing while exiting the lockdown. Testing and isolation of positive cases are the most effective ways of preventing the spread of virus and gradually returning life back to normality. Keywords COVID-19 Á Laboratory testing Á RT-qPCR Á Serological test Á SARS CoV-2 Á Antigen Á Antibody Á
La Medicina del Lavoro, 2021
Background: Healthcare workers (HCW) are at increased risk of being infected with SARS-CoV-2; while PCR test remains gold standard for diagnosis of COVID19 infection, antigen based rapid detection tests have been recently approved by OMS. Methods: We pooled data on occupational surveillance of 6,397 asymptomatic HCW and other employees who were tested for SARS-CoV-2 infection at the University Hospital in Bologna using rapid antigen test between November 16, 2020 and January 29, 2021. Findings: A total of 17,993 rapid tests were performed, of which 704 for contact with an infected person and 17,289 for voluntary screening. Among 17,732 tests with valid results, 87 tested positive (0.49%) and 17 weakly positive (0.10%). The sensitivity of the antigenic test was 88.6% (81.1-96.1), the specificity was 93.4% (89-97.8), the positive predictive value, given a prevalence of infection of 42.1%, was 90.7% (84.8-96.6).
Journal of Medical Virology, 2021
The use of Antigen point of care tests (AgPOCT) might be an essential tool to fight the coronavirus disease 2019 (COVID-19) pandemic. Manufacturer information indicates a specificity of about 95% and there is a growing interest to use these tests area-wide. Therefore, it is necessary to clarify whether AgPOCT can be used safely for "rule-in" (detection of positive patients) and for "rule-out" (valid negative testing). Two thousand three hundred and seventy-five patients received polymerase chain reaction (PCR) testing and AgPOCT for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) regardless of symptoms. The positive predictive value of symptomatic and asymptomatic patients was compared with a cutoff threshold cycle (C t) value of ≤30 and in total. Five hundrded and fifty-one patients tested positive for the SARS-CoV-2 virus by PCR, of whom 35.2% presented without symptoms. In all patients, regardless of their symptoms or C t values, a sensitivity of 68.9% and a specificity of 99.6% were calculated for AgPOCT. In patients with C t values ≤30, a sensitivity of 80.5% (95% confidence interval: ±1.62) and a specificity of 99.6% were shown for all tests (symptomatic/asymptomatic). Highly infectious patients (C t ≤ 20), regardless of symptoms, were reliably detected by the AgPOCT. In infectious patients with C t values ≤30, the test has a sensitivity of about 80% regardless of COVID-19 typical symptoms, which is apparently less than the 96.52% specificity indicated by the manufacturer. Relevant improvement in test sensitivity by querying the patients who are symptomatic and asymptomatic is also not feasible. We strongly suggest that we critically question the use of AgPOCT for "ruleout," as they only provide a supposed safety.
Re-positive PCR of SARS-CoV-2 in health care persons during COVID-19 pandemic
Cellular and Molecular Biology
Reinfection rate with SARS-CoV-2 and degree of protection by the induced antibody after the first episode of the infection is not well known, so it makes a big dilemma for health care personnel (HCP) who work in the front line of combating SARS-CoV-2. In this study, we investigated the frequency of SARS-CoV-2 redetection among HCP after the initial onset of the infection in a children’s hospital during one year. Out of 131 seropositive HCP, 13.7% of them were symptomatic and PCR positive during 74-360 days after first sampling. Analysis of demographic data of seropositive HCP showed a correlation between a higher number of family members, higher body mass index, and the existence of underlying diseases with SARS-CoV-2 redetection. In conclusion, reinfection is one of the important problems in the SARS-CoV-2 pandemic. Research on this topic can help us to find answers to questions for estimating the duration of human protection with produced immunity after the infection or vaccination.
The Journal of Infectious Diseases, 2021
It is currently unknown how post-COVID-19 syndrome (PCS) may affect those infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This longitudinal study includes healthcare staff who tested positive for SARS-CoV-2 between March and April 2020, with follow-up of their antibody titers and symptoms. More than half (21 of 38) had PCS after 7–8 months. There was no statistically significant difference between initial reverse-transcription polymerase chain reaction titers or serial antibody levels between those who did and those who did not develop PCS. This study highlights the relative commonality of PCS in healthcare workers and this should be considered in vaccination scheduling and workforce planning to allow adequate frontline staffing numbers.