There are two types of detection kits for coronavirus disease 2019 (COVID-19): 1) reverse transcription-polymerase chain reaction (RT-PCR) and 2) antibody-based detection kit.
RT-PCR is a laboratory technique combining reverse transcription of RNA into DNA and amplification of specific DNA targets using PCR.
On the contrary, antibody-based detection kits identify the presence of antibodies produced by the host immune system against the virus.
Each type has its advantages and disadvantages, which are summarized in Table 1 and delineated below in detail.
|RT-PCR-based|| ▪ Faster than previous pan-coronavirus testing. |
▪ Highly sensitive and accurate.
▪ Detects viruses earlier in an infection.
| ▪ More labor and time-intensive than antibody-based testing. |
▪ Diagnostic specificity and sensitivity may be affected in the case of mutation.
|Antibody-based||▪ Quick and cheap. |
▪ Able to detect the virus in non-respiratory body fluids (e.g., blood).
▪ Conducive to tracking the virus’s path and understanding its epidemiology.
| ▪ Not as sensitive as RT-PCR-based testing (prone to false negative). |
▪ Continues to be positive for previously exposed individuals (prone to false positive).
Table 1. Pros and cons of RT-PCR-based and antibody-based detection kit
RT-PCR-based detection kit. Using real-time RT-PCR, the test can be done on respiratory samples obtained by various methods such as swabbing a person’s nose or throat to collect phlegm coughed up from the lungs, or squirting liquid into the nose, throat, or lungs.
Since the virus that causes COVID-19 has RNA as its genetic material, RNA must first be copied into DNA to begin PCR. Then, specific DNA targets are amplified using PCR to go through analyses.
Figure 1 is a visualization of the RT-PCR procedures. Figure 2 is the equipment required for RT-PCR-based detection (ABI7500 and Bio-Rad). This equipment is used for RNA preparation, amplification, and analysis.
Figure 1. RT-PCR detection procedures
Figure 2. the equipment required for RT-PCR-based detection (ABI7500 and Bio-Rad)
In general, the results are available within a few hours. This is faster than previous pan-coronavirus testing, of which the process is more comprehensive and thus usually takes about one day for results.
RT-PCR saves time by comparing certain protein genes of the coronavirus. RT-PCR became available after the World Health Organization (WHO) identified the sequence of COVID-19 because it enabled firms to come up with RT-PCR kits that detect whether a sample has the genome sequence to draw out results. Another benefit of an RT-PCR test is that it may be able to detect viruses earlier in an infection.
Specifically, when the virus is replicating strongly, but the body’s immune system has not begun to fight and produce symptoms, an RT-PCT test may detect the viruses during the most contagious period for a person.
Although RT-PCR is a highly sensitive test, it also has some drawbacks. Most importantly, it is significantly more labor and time-intensive than antibody-based detection. Also, RT-PCR primers are designed against conserved regions of the SARS-CoV-2 viral genome (the virus that causes COVID-19).
However, Coronaviruses are capable of making mutations and recombination events. It indicates that the diagnostic specificity and sensitivity of RT-PCR may be affected if the mutation occurs. Another limitation is the reliability of RT-PCR detection. Although positive results are indicative of active SARS-CoV-2 infection, there is a possibility of bacterial infection or co-infection with other viruses.