[Investigation of SARS-CoV-2-Specific Humoral and Cellular Immunity Values in Health Care Workers with COVID-19 Disease and Administered with COVID-19 Vaccine]. / COVID-19 Geçiren ve COVID-19 Asisi Olan Saglik Çalisanlarinda SARS-CoV-2'ye Özgü Humoral ve Hücresel Bagisiklik Degerlerinin Arastirilmasi.

For limiting the coronavirus disease-2019 (COVID-19) pandemic, the effects on both humoral and cellular immune responses due to vaccines and previous infection should be taken into consideration. In some of the studies about the humoral immune response of the virus and different vaccines, it has been suggested that there can be a discordance between cellular and humoral immune responses during COVID-19 infection. The aim of this study was to determine the effects of humoral and cellular immune responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigens in three groups of healthcare workers (HCWs) who were vaccinated with two doses of inactivated virus vaccine (CoronaVac), non-vaccinated and recovered COVID-19 infection and non-infected healthy controls by comparing the variables of gender and age and to examine the relationships between them. In this study, the antibody recognizing the receptor binding domain (RBD) of the spike (S) glycoprotein (IgG-S), nucleocapsid protein (IgG-N) of SARS CoV-2 and Interferon Gamma (IFN-γ) titres were determined among non-infected and vaccinated with two doses of inactivated virus vaccine (IVV) (n= 56, 1st group: 27 men, 29 women), non-vaccinated and COVID-19 convalescents (CG) (n= 41; 2nd group: 21 men, 20 women) and non-vaccinated and non-infected healthy controls (HCG) (n= 23, 3rd group: 10 men, 13 women) in 120 HCWs. Diagnosis of all the participants in COVID-19 CG was confirmed for SARS CoV2 infection with reverse transcription polymerase chain reaction (RT-PCR) test according to manufacturer's instruction (Bio-speedy® SARS CoV-2 Double Gene RT-qPCR, Bioeksen R and D Technologies, Turkey). IgG-S and IgG-N antibody levels were determined quantitatively by Abbott Architect i2000 (Abbott Laboratories, Abbott Park, IL, USA) system. (Qiagen, MD, USA). IFN-γ levels were determined by using the QuantiFERON SARS-CoV-2 Starter Blood Collection Tubes (Qiagen, MD, USA). All statistical data analysis were conducted using SPSS (version 22, IBM Corp., Armonk, NY, USA). Student's independent t-test or Mann-Whitney U test was used for the differences between bivariate groups and Spearman Rank correlation was used to evaluate the monotonic relationship between nonnormally distributed data sets. Spearman rho > 0.7 denotes high, 0.7 > rho > 0.5 moderate and rho > 0.05 was considered as significant. For each of the immunity parameters, there were no significant differences between males and females in the IVV group, as well as in the CG. In neither of the groups age and immunity parameters were found to be highly correlated. All three immunity parameters of males in CG and IVV groups significantly differed from each other. Although humoral immunity parameters of females between CG and IVV groups did not show any significant difference, the IFN-γ titres significantly differed from each other. There were no significant differences in the IgG-S titres between CG and IVV combined gender groups. However, IgG-N and IFN-γ titres significantly differed from each other between CG and IVV groups. Antibody and particularly IFN-γ levels in two dose CoronaVac vaccinated group were less pronounced in comparison to the observed responses in COVID-19 convalescents group, indicating that CoronaVac may induce substantially less robust and persistent cellular and humoral responses than natural SARS-CoV-2 infection.

Clinical Accuracy of Instrument-Read SARS-CoV-2 Antigen Rapid Diagnostic Tests (Ag-IRRDTs).

This systematic review (PROSPERO registration number: CRD42021282476) aims to collect and analyse current evidence on real-world performance based on clinical accuracy of instrument-read rapid antigen diagnostic tests (Ag-IRRDTs) for SARS-CoV-2 identification. We used PRISMA Checklist and searched databases (PubMed, Web of Science Core Collection and FIND) for publications evaluating the accuracy of SARS-CoV-2 Ag-IRRDTs as of 30 September 2021, and included 40 independent clinical studies resulting in 48 Ag-IRRDT datasets with 137,770 samples. Across all datasets, pooled Ag-IRRDT sensitivity was 67.1% (95% CI: 65.9%-68.3%) and specificity was 99.4% with a tight CI. Pooled sensitivity and specificity of SARS-CoV-2 Ag-IRRDTs did not demonstrate a significant superiority over SARS-CoV-2 rapid antigen tests which do not require a reader instrument, even in the case where surveillance and screening datasets were excluded from the analysis. Nevertheless, they provide connectivity advantages and remove operator interface (in results-reading) issues. The lower sensitivity of certain brands of Ag-IRRDTs can be overcome in high prevalence areas with high frequency of testing. New SARS-CoV-2 variants are major concern for current and future diagnostic performance of these tests.

[Evaluation of a Visually-Read Rapid Antigen Test Kit (SGA V-Chek) for Detection of SARS-CoV-2 Virus]. / SARS-CoV-2 Virüs Tespitinde Görsel Okunan Hizli Antijen Test Kitinin (SGA V-Chek) Degerlendirilmesi.

Although the reverse transcriptase polymerase chain reaction (RT-PCR) method has been accepted as the reference method in the detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA, it requires special laboratory conditions, complicated and expensive laboratory instruments, competent laboratory staff and long testing duration. Antigen testing methods such as enzyme immunoassay, fluorescent antibody and visually-read immunochromatographic rapid antigen detection (RAD) tests eliminated the above mentioned disadvantages of the RT-PCR. The aim of this study was to determine the performance of a RAD test kit (V-Chek, SGA Ltd, Ankara, Turkey). Two paired nasopharyngeal swabs were collected from each patient, and one of them was used for the RAD test, while the other one (different swab) was used to perform the RT-PCR test. SARS CoV-2 Double Gene RT-PCR kit (Bioeksen, Turkey) was used for RNA amplification on the Light Cycler 480 plate-based RT-PCR instrument (Roche, Switzerland). The SARS-CoV-2 double gene RT-PCR kit targeting the SARS-CoV-2 specific N (nucleocapsid) and Orf1ab gene regions was used for RNA amplification. The human RNaseP gene was used for nucleic acid extraction and inhibition control. The shape of the growth curves was examined and the non-sigmoidal curves were recorded as "negative". Sigmoidal curves with cycle threshold (Ct) <38 were evaluated as "positive". The Ct values of all positive results were recorded. V-Chek RAD test kit uses a colloidal gold enhanced double antibody sandwich type antigen test kit. A SARS-CoV-2 positive specimen produces a distinct color band in the test region, formed by the specific antibody-antigen colored conjugate complex. A positive or negative result is indicated by a colored line appearance on the test region. A colored line appears in the control region, independent of the SARS-CoV-2 presence. The result is visually read 10 minutes after the last drop of the sample liquid is dispensed into the sample well. Specificity and sensitivity values were calculated accepting the RT-PCR results as a standard. Agreement between two different techniques was assessed using Cohen's kappa score. 110 patients were enrolled in this study; 34 (30.9 %) of these patients had positive RT-PCR samples, with the mean of Ct values of 25.8 (95% CI= 24.1-27.5), median of Ct values of 26. In our study population, the overall sensitivity was 61.8% (95% CI= 45.4-78.1), and specificity was 100%. Taking RT-PCR as reference, Cohen's kappa score for the antigen test was 0.691. Fisher's exact test was p<0.001. In conclusion, the RAD kit used in the study determined to be useful for the rapid identification of COVID-19 patients. However, a negative result does not eliminate the possibility of COVID-19 infection and should be confirmed by RT-PCR and clinical findings.