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. 2021 Feb 3;14:379–389. doi: 10.2147/RMHP.S284473

Table 2.

Available Diagnostic Methods for the Detection of COVID-19

Method Basis Mechanism Advantage Limitations
Molecular Identification and amplification of viral-specific RNA sequence. Based on principles of rRT-PCR technology.
Separation of reporter and quencher dye occurs through exonuclease activity of taq polymerase resulting in the production of fluorescence intensity detected through PCR software.		 Different viral targets are adopted by different countries. USA targets three regions within the N gene. Germany targets the E gene and RdRP genes of subgenus Sarbecovirus. Hong Kong undergoes screening assay of N gene followed by confirmation using ORF1b assay.
Various molecular
Diagnostic POC kits have been approved.

  1. The chances of false-negative results are high.

  2. Not specific for SARS-CoV-2.

  3. Amplification inhibitors can interfere with the process.
Serological Antibody testing It involves the identification of antibodies in the host or viral-specific proteins through assays such as neutralization assay (ELISA), chemiluminescent immunoassay and rapid diagnostic tests (lateral flow assay).
In this process, the antigen-antibody complex is formed which is recognized by a secondary antibody that produces a detectable color change or shows light-emitting properties.		 Various immunodiagnostic POC kits have been approved for commercialization. These works on the principle of ELISA or lateral flow assay.

  1. Lack of sensitivity and specificity.

  2. Early virus infection cannot be detected.

  3. Antibody production in the host depends upon the immune response of an individual.

  4. The tendency to give false-positive results.
Laboratory and point of care devices Identification of viral RNA sequence or viral-specific antigens/host antibodies. Molecular devices work by identifying the specific sequence of the RNA genome and then amplifies it to the point it becomes easily detectable.
Similarly, serology-based devices depend upon the ELISA technique for the identification of host antibodies and viral proteins.		 Various molecular devices have been approved for emergency use authorization. One such is Abbott ID that runs on Abbott’s ID NOWTM platform- a lightweight box that can be fit and adjusted in different locations. It gives positive results in 5 minutes and negative results in 13 minutes.

  1. Well-trained professionals are required.

  2. The chances of miss-interpretation of data are high.
Radiological Identification of clinical changes in the patient’s respiratory system It is a medical imaging technique that uses CT scan and CXR for giving a greater view of internal organs, bones and soft tissues. CT scan is appropriate for studying the symptoms of pneumonia.
Different clinical stages were observed in the patients as the disease progressed. First GGO lesion to multifocal GGO lesion then septal thickening of inter and intralobular followed by the formation of the consolidated lesion was observed.		 1.Varied representation of clinical changes among patients.
2. Cannot be used alone, must be used with molecular diagnostic approaches for confirmation of results.
Cell culture Isolation of SARS-CoV-2 on cell lines promoting growth and replication of the virus. Vero E6 cell lines are very sensitive to the viral replication of SARS-CoV. Upon virus replication, cell death occurred due to apoptosis, and the cells which survived the replication process showed morphology similar to the uninfected cells supporting the production of these infectious agents. Vero E6 cells expressing TMPRSS2 showed more production of viral mRNA transcripts suggesting a probable role of TMPRSS2 in virus replication. A ~10-fold higher activity was observed as compared to other cell lines.

  1. Lack of available permissive cell lines in laboratories.

  2. Well-trained professionals are required.

  3. Can be performed only under BSL-3.

Abbreviations: r-RT-PCR, real-time reverse transcriptase-polymerase chain reaction; N, nucleocapsid; E, envelope; RdRP, RNA dependent RNA polymerase; ELISA, enzyme-linked immunosorbent assay; POC, point of care; CXR, chest X-ray; CT, computed tomography; GGO, ground-glass opacities; TMPRSS2, transmembrane protease serine 2; BSL, biosafety level.

Notes: Data from Asrani et al.1515