Rapid and large-scale establishing, tracking, tracing, and isolating (TTTI) have proven critical for public health policy responses during the coronavirus disease 2019 (COVID19) epidemic. Numerous COVID-19 tests have been created, each with its own set of advantages and disadvantages. Effective testing techniques can leverage the strengths and weaknesses of many tests to achieve complementarity.
Covid-19 test types
COVID-19 testing is classified into two groups based on their ability to detect active infection: molecular and fast antigen tests. At any moment, the third type of test, the antibody test, can be used. The RT-PCR and LFT are two distinct antigen tests discussed below (1 and 2), followed by a brief discussion of the antibody test (3), which is used to detect a past infection with the virus.
The Reverse Transcriptase – Polymerase Chain Reaction (RT-PCR) is the most conventional approach available for screening for the presence of RNA, which is detectable during the early stages of infection ––before the body has time to produce antibodies against the infection. To enable detection, reverse transcriptase (or DNA polymerase may also be used) amplifies the RNA molecule. It is a particular and sensitive test, albeit findings are obtained more slowly because samples are submitted to a laboratory for analysis. Due to the high expense of this type of test, its application on a large scale has been limited. Additional disadvantages include the following:
- Positive outcomes are challenging to interpret.
- Supply constraints on critical testing supplies –– nasal swabs, reagents, and transport media
- Protracted lead times (in addition to lab processing time) are necessary due to logistics associated with transporting samples, etc.
RT-LAMP test at the point of care
The RT-LAMP test is similar to the RT-PCR test. It can be utilized at the point of care without requiring the sample to be sent to the laboratory, therefore overcoming the disadvantage of a significant lead time.
A test based on CRISPR
This method identifies a sequence of SARS-CoV-2 RNA and cuts apart any surrounding single-stranded RNA. The cuts result in the release of a separately inserted fluorescent particle into the test fluid, which can then be identified using a laser, indicating the presence of genetic material.
Rapid antigen detection test
These tests are now commonly referred to as the lateral flow test (LFT). While this type of test is less reliable than the RT-PCR test, it has the advantage of being quick and straightforward to apply, providing a speedy test result on a more cost-effective scale.
These serological tests cannot be used to detect active COVID-19 infection; instead, they are used to determine whether a person has ever had the illness. These tests are critical for determining infection rates in a population and have epidemiological significance. This type of test is especially advantageous because many persons with the virus are asymptomatic and may have been infected without realizing it. In addition, antibody testing has been used to determine if those vaccinated against SARS-CoV-2 developed an immunological response.
This type of test demands a blood sample from patients rather than a swab. The tests are available in various formats, ranging from the complicated and laboratory-based (e.g., ELISA testing) to the more straightforward fast tests utilized at the point of care.
Although these tests are critical for epidemiology and vaccine development, they are useless for applying TTTI tactics due to their inability to detect current, active viral infections. Finally, scientists are unsure how long vaccine-induced immunity will endure. As the threat of new variations grows, the necessity for booster immunizations becomes a constant possibility.
How is the examination conducted?
Molecular assays employ particular probes to detect the presence of the novel coronavirus’s genetic material. In addition, numerous molecular assays can detect numerous viral genes rather than just one, increasing their sensitivity.
The majority of molecular tests require a sample to be taken using a nasal or throat swab. Additionally, specific molecular assays can be performed on saliva collected by spit into a tube.
You can obtain a molecular test at a variety of sites, including but not limited to the following:
- urgent care facilities
- community-based Sites for COVID-19 testing
- at ease
When should I anticipate receiving my results?
The turnaround time for molecular tests varies. For instance, findings from specific point-of-care testing can be obtained in 15 to 45 minutes. However, when samples must be sent to a lab for analysis, it may take between one and three days to receive a result.
How precise is this examination?
The molecular test is the “gold standard” for COVID-19 diagnosis. For instance, a 2021 Cochrane review discovered that molecular tests diagnosed 95.1 percent of COVID-19 cases correctly.
As a result, a positive molecular test result is frequently sufficient to diagnose COVID-19, particularly if you also have COVID-19 symptoms. Typically, the test does not need to be repeated once you obtain your results.
A false-negative result on a molecular test is possible. Besides sample collection, transport, and processing issues, timing can be critical.
Testing too soon: It can take up to five days following exposure for the virus’s genetic material to be discovered, which means that you may have a false-negative result if you are tested during this period.
Testing too late: After the first week, the viral genetic material in the upper respiratory tract begins to decline of sickness. As a result, getting tested late may result in a false-negative result.
As a result of these circumstances, it is critical to seek testing as soon as you begin experiencing symptoms consistent with COVID-19.
How much is it?
The Families First Coronavirus Response Act (FFCRA) ensures that all individuals, regardless of insurance status, have free COVID-19 testing. This involves tests at the molecular level. A molecular test is predicted to cost between $75 and $100. A Reliable Source
Read More: How to keep your lungs strong for COVID-19