Abstract
Background Currently, a novel coronavirus found in 2019 known as SARS-CoV-2 is the etiological agent of the COVID-19 pandemic. Various parameters including clinical manifestations and molecular evaluation can affect the accuracy of diagnosis. This review aims to discuss the various clinical symptoms and molecular evaluation results in COVID-19 patients, to point out the importance of onset symptoms, type, and timing of the sampling, besides the methods that are used for detection of SARS-CoV-2. Methods A systematic literature review of current articles in the Web of Science, PubMed, Scopus, and EMBASE was conducted according to the PRISMA guideline. Results Of the 12946 patients evaluated in this investigation, 7643 were confirmed to be COVID-19 positive by molecular techniques, particularly the RT-PCR/qPCR combined technique (qRT-PCR). In most of the studies, all of the enrolled cases had 100% positive results for molecular evaluation. Among the COVID-19 patients who were identified as such by positive PCR results, most of them showed fever or cough as the primary clinical signs. Less common symptoms observed in clinically confirmed cases were hemoptysis, bloody sputum, mental disorders, and nasal congestion. The most common clinical samples for PCR-confirmed COVID-19 patients were obtained from throat, oropharyngeal, and nasopharyngeal swabs, while tears and conjunctival secretions seem to be the least common clinical samples for COVID-19 diagnosis among studies. Also, different conserved SARS-CoV-2 gene sequences could be targeted for qRT-PCR detection. The suggested molecular assay being used by most laboratories for the detection of SARS-CoV-2 is qRT-PCR. Conclusion There is a worldwide concern on the COVID-19 pandemic and a lack of well-managed global control. Hence, it is crucial to update the molecular diagnostics protocols for handling the situation. This is possible by understanding the available advances in assays for the detection of the SARS-CoV-2 infection. Good sampling procedure and using samples with enough viral loads, also considering the onset symptoms, may reduce the qRT-PCR false-negative results in symptomatic COVID-19 patients. Selection of the most efficient primer-probe for target genes and samples containing enough viral loads to search for the existence of SARS-CoV-2 helps detecting the virus on time using qRT-PCR.
Highlights
Coronaviruses are enveloped, nonsegmented, positive-sense RNA viruses. ey belong to Coronaviridae and Coronavirinae, which are divided into four genera, namely, alpha, beta, gamma, and delta coronaviruses [1]. e genus Betacoronavirus comprises five subgenera including Embecovirus, Sarbecovirus, Merbecovirus, Nobecovirus, and Hibecovirus [2]
On March 2, 2020, a coronaviridae study group of the international committee on taxonomy of viruses (ICTV) declared their decision regarding the change of the name of the novel coronavirus to severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) which is accountable for the COVID-19 pandemic [3]
Different diseases which cause pneumonia often have the same symptoms, which makes it hard to determine the exact cause of the disease in order to start medication, and the disease caused by SARS-CoV-2 is not an exception. e main symptoms for COVID-19 are reported to be fever and fatigue, followed by sore throat and dyspnea and even, in some cases, neurological symptoms [9,10,11]
Summary
Coronaviruses are enveloped, nonsegmented, positive-sense RNA viruses. ey belong to Coronaviridae and Coronavirinae, which are divided into four genera, namely, alpha, beta, gamma, and delta coronaviruses [1]. e genus Betacoronavirus comprises five subgenera including Embecovirus, Sarbecovirus, Merbecovirus, Nobecovirus, and Hibecovirus [2]. Using the most sufficient gene for RT-real-time PCR (as the molecular method) and considering the onset symptoms is of great importance in the process of detecting the infected patients. Is study aims to point out the importance of clinical manifestations, detection methods of SARS-CoV2, and timing and the types of samples in better detection of infected individuals with the aim of restricting the spread of the virus. Is review aims to discuss the various clinical symptoms and molecular evaluation results in COVID-19 patients, to point out the importance of onset symptoms, type, and timing of the sampling, besides the methods that are used for detection of SARS-CoV-2. Selection of the most efficient primer-probe for target genes and samples containing enough viral loads to search for the existence of SARS-CoV-2 helps detecting the virus on time using qRT-PCR
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