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How much do you know about the tests to detect the coronavirus?

Ramiro Guzman
6 min read
How much do you know about the tests to detect the coronavirus?
Today there are several "COVID-19 tests" so it is important to differentiate them

The pandemic once again reached a historic upturn that had not been seen since the beginning of 2020. That is why the application of "Covid-19 tests" increased proportionally.

But... Would you know exactly which is which? As can be seen, each test has its characteristics and objectives. Although the end result is the same, its scope is not always accurate.

Brief introduction to the world of "COVID-19 tests"

The term "tests" is used colloquially to refer to a clinical laboratory study. Through it, it is possible to detect if a person is infected with SARS-CoV-2 or "the new coronavirus".

It is important to highlight that they are divided according to their objective: to diagnose or detect antibodies. Therefore, they have obvious indications as the case may be.

According to information provided by the FDA (Food & Drug Administration), diagnostic tests are the most widely used. Molecular tests and tests against antigens that reveal positive or negative status for active coronavirus infection are derived from them.

How much do you know about the tests to detect the coronavirus?
Diagnostic tests consist of nasal and/or nasopharyngeal swab

For its part, antibody tests are indicated to determine the presence of antibodies against the pathogen in the blood. Its use is discontinued for the diagnosis of passive infection.

It only serves to confirm that, indeed, at some point the infection was contracted. Otherwise, they are complementary to molecular and antigen tests since they increase their specificity.

How are the main diagnostic tests different?

As its name indicates and explained above, they are the tests used for a quick diagnosis. In addition, they verify the true state of active coronavirus infection in a sick patient.

The two main ones for screening or diagnosis are the PCR (Polymerase Chain Reaction) of antigens. Both work with different methods, but their principle is identical: the sample is obtained thanks to a swab.

Essentially, the purpose of the swab is to obtain a liquid sample from the nose or throat. Among other techniques promoted, the patient may spit saliva into a test tube for analysis.

PCR or Polymerase Chain Reaction Test

It is the most accurate diagnostic test that exists in contrast to the antigenic one. This is a strict analysis at the molecular level for the detection of the genetic material of the pathogen.

How much do you know about the tests to detect the coronavirus?
The basic operation is based on the process of "polymerase chain reaction — reverse transcriptase"

It is called in such a way, since the principle or technique used is the "polymerase chain reaction". A scientific circuit that, for laboratory and diagnostic purposes, is an ace up the sleeve.

The test result is displayed in a matter of a few minutes. However, when there are logistics or external analysis issues, it can vary from hours to days.

Depending on access to technology, the diagnosis may or may not be timely.

Antigen test

Every pathogenic microorganism upon entering the individual's body triggers an immune response. She is subject to exposure to certain infectious agent proteins known as "antigens."

When performing the swab and obtaining the sample, it is placed in a device similar to pregnancy tests. This artifact is primed to react to these viral proteins and, if present, will yield a positive result.

How much do you know about the tests to detect the coronavirus?
Example of a positive antigen test (double line) with a negative (one line)

Unlike its predecessor, it does not require extensive molecular study or special laboratory machinery.

But unfortunately, it is more prone to false negatives. That is, his diagnosis is not so certain.

In some countries it is classified as a very subjective test due to the poor technique to which it is prone. If the proper and described steps are not followed, the risk of contamination and unreliable results is high.

Key moments to perform any diagnostic test

Many people still do not know the exact time to undergo any of these tests.

Unfortunately, there is also evidence of a series of conspiracy theories that hinder the process and bias the medical argument.

For general purposes, diagnostic tests are not only indicated when there is suspicious symptomatological evidence for COVID-19. On the contrary, there are several key moments considered opportune:

  1. Contact of any kind, mainly close or close, with people confirmed for coronavirus infection.
  2. After participating in activities that involve large concentrations in crowded spaces. Or, on the other hand, trips, family gatherings and all kinds of situations that are related to close contacts regardless of positivity.
  3. By medical indication as an essential requirement for any surgery or health protocol. Also, as prevention and care against disease in general.
How much do you know about the tests to detect the coronavirus?
The appearance of suspicious symptoms is not the only key moment to carry out the test

It should be noted that the test is performed regardless of the individual's vaccination status. Remembering, immunizations DO NOT exclude coronavirus infection, but DO reduce the chances of severe respiratory disease.

Interpretation of the obtained results

Assimilating the results after carrying out a test marks a turning point. Whether positive or negative, it will determine precisely the next step to take. In that sense, learning to interpret the panorama will be key to moving forward.

  1. Positive: means that the diagnostic test has found the antigen or genetic code of SARS-CoV-2. At that moment, it is verified that the patient suffers from the active infection of the disease.
  2. Negative: symbolizes the opposite scenario where the presence of the pandemic virus is not detected. However, it is not a reason to relax or relax prevention measures.
  3. False positive: it is when the test shows the detection of the properties of the virus, but in reality it is not. It is a secondary result of poor sample collection or test preparation as such.
  4. False negative: On the other hand, a false negative is when the test shows that the virus is not present. But, the reality is that the person is infected and is a carrier of the disease. It is also secondary to poor technique in the use of the test.

The recommendations in each case is to emphasize the biosecurity strategy. As a key point, the Centers for Disease Control and Prevention (CDC) communicated new guidelines.

All this in the framework of novel studies carried out on the spread of the infection.

If a result is positive, after 5 days of absence of symptoms with 24 hours without fever, it is possible to return to standard activities. As long as the mask is strictly worn and biosecurity measures are applied.

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