False-negative results may occur by mutations in the primer and probe target regions in the SARS-CoV-2 genome. ... Several types of SARS-CoV-2 real-time RT-PCR kit have been developed and approved rapidly, but with different quality. Importantly, the sensitivity and specificity of the real-time RT-PCR test is not 100%.
.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7189409/
An important issue with the real-time RT-PCR test is the risk of eliciting false-negative and false-positive results. It is reported that many ‘suspected’ cases with typical clinical characteristics of COVID-19 and identical specific computed tomography (CT) images were not diagnosed. Thus, a negative result does not exclude the possibility of COVID-19 infection and should not be used as the only criterion for treatment or patient management decisions. It seems that combination of real-time RT-PCR and clinical features facilitates management of SARS-CoV-2 outbreak. Several factors have been proposed to be associated with the inconsistency of real-time RT-PCR. In the following, we attempt to discuss various challenges regarding the detection of SARS-CoV-2 by real-time RT-PCR. It is expected that this could provide beneficial information for the comprehension of the limitations of the obtained results and to improve diagnosis approaches and control of the disease.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7189409/
The results of real-time RT-PCR tests must be cautiously interpreted. In the case of real-time RT-PCR negative result with clinical features suspicion for COVID-19, especially when only upper respiratory tract samples were tested, multiple sample types in different time points, including from the lower respiratory tract if possible, should be tested. Importantly, combination of real-time RT-PCR and clinical features especially CT image could facilitate disease management. Proper sampling procedures, good laboratory practice standard, and using high-quality extraction and real-time RT-PCR kit could improve the approach and reduce inaccurate results.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7189409/
There are three main types of detection assays relevant for COVID-19 diagnostic testing and screening, based on the target that is being detected:
Nucleic acid tests detect the presence of viral RNA. Typically, these use an amplification step based on RT-PCR.
Antigen tests detect the presence of a viral antigen, typically part of a surface protein.
Antibody tests detect the presence of antibodies generated against SARS-CoV-2. The three most used assays are enzyme-linked immunosorbent assays (ELISA), chemoluminescence assays (CLIA) and lateral flow assays (LFA). In addition, virus neutralisation tests are used, which can specifically detect neutralising antibodies, but this is mainly used for assay validation and research. Preliminary reports on ELISA assays have shown good correlation of antibody titration results with virus-neutralising antibodies
https://www.ecdc.europa.eu/en/covid-19/latest-evidence/diagnostic-testing
thanks dear doctor for your kind contribution Chinaza Godswill Awuchi
https://www.frontiersin.org/articles/10.3389/fpubh.2020.594458/abstract