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The Different Types Of Covid-19 Tests

The first step to deal with the Coronavirus infection and treat it is to diagnose it. In this article, the various types of Covid-19 tests and their limitations have been discussed. But first, what is the Coronavirus? Coronavirus is an infectious and highly contagious disease that causes severe respiratory illness. Most infected people only develop mild to moderate symptoms and may recover quickly with early diagnosis, suitable medication, and treatment. But patients with severe symptoms might need immediate hospitalization and over 38 lakh people around the world have already been succumbed to the virus with over 17 crore people affected in totality, as of 15th June 2021.

Covid-19 Testing

Since the emergence of the novel Coronavirus last year, it has constantly been evolving and mutating. In such a case, it is necessary to have knowledge about and access to reliable and effective tests. Some of these tests are based on saliva and mucus, and some on blood tests. Given the various options, you might wonder- “How do these tests work?”, “Which type of Covid-19 test is more reliable?”, “Which test will work best for me?” “Do they all work the same?” and “Is there a diagnostic test for covid-19?”. Let’s see them all:

So, how many different Covid-19 tests are there?

There are three different tests known to search for the virus or detect its presence in the body. The screening or the tests are of various kinds- the antibody test, the RNA test, or the antigen test for the Covid-19. The antibody tests screen for antibodies to fight the virus in the blood. And, the antigen tests look for a coating of the Covid-19. The RNA tests, on the other hand, detect acid belonging to the novel Coronavirus. Different samples are required for either kind of test in order to search for the hallmarks of the virus. The 3 types are:

1. Lateral Flow Test or LFT
2. Polymerase Chain Reaction Test or PCR
3. Antibody/Serology Tests or Blood Test

1. Lateral Flow Tests or LFT (a.k.a. Rapid Test)

FT is an antigen test, meaning it is designated to screen for the active Covid-19 infection instead of the antibodies created by the immune system of the body’s immune system in protection from the virus. It is a diagnostic test also known as a “rapid test.” LFT is called so because it is a quick test with instant results. In the test, a nasopharyngeal sample is placed upon a small and absorbent pad. The sample is then drawn along the pad to a strip covered with the antibodies using a capillary line. These antibodies bind to the SARS-Cov-2 proteins. So, if a colored line appears on the test, it indicates the presence of the infection. Lateral Flow Tests are commonly used in places where many people need to be screened, like airports.

Benefit:

The main benefit of a Lateral Flow Test is that it is faster than molecular tests and doesn’t need to be sent to the labs for long hours. It is also helpful in detecting asymptomatic carriers.

Limitation:

However, due to the quickness of the test, the rapid Covid test accuracy is compromised to a certain extent. If you test positive, it is most likely accurate, but if you show Covid-19 symptoms and yet the test shows a negative, your doctor may advise you to take a molecular test, more commonly known as a PCR test, to confirm the result.

2. Polymerase Chain Reaction or Molecular Test

A PCR test is quite similar to a Lateral Flow Test. But a PCR test directly screens for an active infection, which will be detectable before the symptoms of the disease are present, or the antibodies are formed. It is useful in detecting the virus in the early stages.

In order to perform the test, mucus is collected from your nose or throat or both, using a specialized swab. These swabs are then taken to a lab, where substances known as DNA polymerase or reverse transcriptase are added to the nasopharyngeal sample. These substances work to multiply the viral RNA present if there’s any. This process takes place in order to make enough copies of the RNA to indicate a positive result.

Benefit:

RT-PCR test for Covid-19 accuracy in results is higher and more effective.

Limitations:

1) The laboratory analysis process can take a few days before the results are returned to you. In this time period, the virus is likely to worsen.

2) PCR tests can also provide a false-positive result. The test is so sensitive that it can detect the deactivated or dead cells present in the body of a recovered person and indicate them as an active infection.

3)It would not help you in determining whether or not you had Covid-19 infection in the past.

Note: In recent months, the availability of “at-home test kits” has allowed people to collect their own sample of mucus or spit and send it to a trusted lab for analysis. These kits are easy and less intimidating to use. It has also been noted that after learning the correct technique of collecting their own sample, people have gotten results just as accurate as those performed by medical professionals.

3. Antibody Test or Serology Test

This test works to detect the antibodies present in your body after you have recovered from the virus. When such a virus infects you, or any foreign entity invades your body, your immune system forms proteins called Antibodies to fight off the virus. It has been found that even after recovering from mild cases of Covid-19, people tend to produce antibodies for at least 5-7 months, if not more. However, the fact that should be kept in mind is that the antibody or serology test does not detect active Covid-19 infection.

Unlike the antigen tests, the antibody test for Covid-19 does not use swabs. Instead, antibody tests use a blood test for covid-19 detection. Blood samples are either drawn from the vein in your arm or via a finger prick in this test. The antibody test requires a blood test, but an antigen test does not because the virus is present in the blood in a minimal quantity and is nearly immeasurable. In contrast, the antibodies in the blood are present in a significant amount following the infection.

The antibody test isn’t recommended until after 14 days of the beginning of the symptoms. Testing too early might not provide an accurate result since your immune system is probably still mounting its defense against the virus.

After recovering from Covid-19, it is suggested not to get the vaccine for the disease in the next 3-4 months. The antibody or serology test is also helpful in determining when and whether or not you should get vaccinated after your recovery.

Along with all the laboratory tests mentioned above, CT scans can also be used to detect the Coronavirus in individuals that have a high clinical suspicion of the Covid-19 infection.

What to do if you test positive for the Covid-19?

If you test positive or show symptoms of the Coronavirus, you should consult a doctor online/offline, provide him/her details of your symptoms thoroughly, and follow home quarantine. You should dedicatedly and timely take your medicines along with healthy meals. Avoid cold drinks and food items. It would help if you took steam regularly. You should also monitor your symptoms regularly and keep your doctor informed of them. Do not ignore it if your fever increases or if you feel breathless. Chest pain or pressure, loss of speech or movement, and skin discoloration should not be taken casually at any cost as they indicate the severity of the disease. Keep your oxygen levels in check and inform your doctor immediately if it goes below 90.

Conclusion

If you get in contact with anyone who is infected with the Coronavirus or if you develop any symptoms, you should contact your doctor as soon as possible. And, on his/her recommendation, contact your nearest Covid-19 testing lab or healthcare provider for testing. If you get an RT-PCR test or an antibody test, self-isolate till you get your results back.

Meanwhile, wear a mask, social distance, avoid touching your face after touching any unfamiliar foreign body, and stay indoors as much as possible until you get fully vaccinated. Stay home, stay safe!

Written by Bhargavi J