Table 2.
Summary of the detection methods and their properties.
| Method | Type(s) of specimens | Sensitivity (%) | LOD | Detection time | Advantages | Limitations | References |
|---|---|---|---|---|---|---|---|
| RT-qPCR | NP and OP swabs, sputum. | 95–100 | 100–500 copies/reaction | 4 h | High sensitivity and specificity for SARS-CoV-2 detection (gold standard). | Requires expensive equipment and trained personnel. Gives false results in samples with low viral loads. | Behera et al., 2021, Kudo et al., 2020 |
| ddPCR | NP swab, sputum. | 94 | 11.1–123.2 copies/reaction | 5 h | Can accurately detect the virus in samples with low viral load, reducing false-negative results. | Expensive and time consuming. | Yu et al., 2020, Suo et al., 2020 |
| RT-LAMP | NP and OP swabs, saliva. | 93.5–97.5 | 100–200 copies/reaction | 30 min | Low cost, rapid, and highly specific. | Sensitivity depends on the viral load; some samples give intermediate results. | Aoki et al., 2021, Oliveira et al., 2021, Thi et al., 2020. |
| Sequencing-based methods | NP swab | 99 | 4.08 ng/μl | 24 h | Can determine the virus origin and mutations. | Expensive. Not suitable for large-scale testing. Sequencing errors occur due to a large number of reads or low viral loads in clinical samples. |
Harilal et al., 2020, Shaibu et al., 2021, Slatko et al., 2018 |
| ELISA | Blood/serum. | 80–85.7 | 1.953–500 ng/mL | 5 h | Can detect recent or previous exposure to SARS-CoV-2. Determines potential serum donors for critically ill patients. | A long time is required to develop assays. Does not directly indicate the presence of infection. Results depend on an individual’s immunity. |
Carter et al., 2020, Iruretagoyena et al., 2021, Vernet et al., 2021 |
| LFA | NP swab, saliva. | 84 | 0.65 ng/mL | 15–30 min | Rapid, small size. Does not require specialized equipment. |
Gives false-negative results in samples with low viral load. Needs optimization. | Li et al., 2020, Grant et al., 2020 |
| CLIA | Blood/serum. | 73.3 for IgM, 76.7 for IgG | 10 AU/mL | 40 min | Rapid. Consumes low amounts of reagents. | Expensive. Results’ accuracy varies based on the time from the disease onset. | Cinquanta et al., 2017, Infantino et al., 2020. |
| Neutralization assays | Human epithelial cells | 95–100 | 3–5 days | Crucial for vaccines development. | Tests must be performed in level 3 biosafety cabinets. | Behera et al., 2021, Carter et al., 2020, Abe et al., 2020 | |
| CRISPR technology | NP swab. | 80–97.1 | 10–100 copies/reaction | 30–60 min | Rapid and simple. Does not require expensive equipment. | Viral mutations cause false results. | Bokelmann et al., 2021, Broughton et al., 2020. |
| Biosensors | NP swab, sputum. | 99 | 1–10 copies/reaction | 10 min | Rapid, cost-effective. Most biosensors are label-free. Provide real-time measurement. |
Produce small response when using small analyte quantity. | Carter et al., 2020, Abid et al., 2021, Chaibun et al., 2021 |
| Nano-based sensors | NP swab. | 100 | 0.18 ng/µl | 20–60 min | Highly sensitive and robust. Simple. Low analyte quantity is sufficient. Improve detection accuracy. | Expensive Require further clinical experimentation. |
Gupta et al., 2020, Patra et al., 2020, Zhu et al., 2020. |
Abbreviations: RT-qPCR, reverse-transcription polymerase chain reaction; ddPCR, droplet digital PCR; RT-LAMP: reverse-transcription loop-mediated isothermal amplification; ELISA, enzyme-link immunosorbent assay; LFA, lateral flow assay; CLIA, chemiluminescent immunoassay; NP, nasopharyngeal; OP, oropharyngeal; IgG, immunoglobulin G; IgM, immunoglobulin M; CRISPR, clustered regularly interspaced short palindromic repeats.