peruvian coronavirus

If lately there is a common feeling that many have experienced, it is the swab test to detect COVID-19. Among the many descriptions, this discarding is associated with a painful experience, similar to the feeling that something ‘arrives’ up to the brain, which generates an aversion and an impulse to rejection.

Since the beginning of the pandemic and in the midst of all the waves of contagion that the country has endured, the majority of the population has had at least one test to rule out COVID-19 in public or private establishments.

However, this particularity of using the swab (swab) occurs mainly in two: the molecular test (PCR) and the antigen test.

What differentiates a molecular test from an antigen test?

It is detailed that the molecular tests detect the genetic material of the virus (RNA), that is, the virus itself, in the samples of nasal mucosa or oral mucosa that are taken from patients. These types of tests are reliable, but they require a laboratory to obtain their results.

Instead, the antigen-based rapid diagnostic tests They also detect the virus, but they do not look for the genetic material, but identify the proteins that are on the outside. This sample is taken using a nasopharyngeal swab and the result is obtained in less than half an hour, since it does not require a laboratory for its processing.

According to an article in The New York Times, at the beginning of the COVID-19 pandemic, the nasopharyngeal swab either deep nasal swab generally in the population. This is because the method worked in tests for influenza and Severe Acute Respiratory Syndrome (SRAG).

“According to a review of studies published in July in the scientific journal PLOS One, nasopharyngeal swabs are 98% accurate; shallow swabs are 82-88% effective and mid-turbinate swabs have similar performance”, reports the TNYT.

Is the nasopharyngeal swab still used in molecular tests (PCR)?

“Let’s say that one is the swab for molecular testing and the other is for antigen testing.those two have a correlation with the swab. (The swab nasopharyngeal) it’s the deepest but it’s going to depend on the markings (because of the size of the swab), this one can be uncomfortable because it goes through the nostril and you have to bend the swab to go deeper in order to get to the pharynx”explains Oscar Escalante Maldonado, director of the Executive Directorate of Communicable Diseases of the INS.

Oscar Escalante points out that when it comes to molecular tests, currently, public establishments of the Ministry of Health (Minsa) do not “They use this type of tests (nasopharyngeal) to avoid the invasion of the patient”.

On the contrary, “It is usually done with two swabs (nasal and oral), one that goes into the nostril to the walls and another that enters through the mouth to touch the pharynx”.

It details that there are two swabs for molecular tests and only one for antigen tests, the latter being still in force in medical centers, private laboratories or marketed in the well-known COVID self-tests that are found in authorized pharmacies.

“Of the antigen tests, these are the fastest with which you have results in 30 minutes. And this test has a single swab that, depending on the manufacturer, can be only nasal or nasopharyngeal (…) The nasopharyngeal swab is designed to be bent, while the other should not be bent because it can break”, specifies Escalante.

Another detail is that each brand (COVID test) details whether it is used as a nasal, nasopharyngeal or oropharyngeal swab (oral route). “Each supplier submits its technical specifications on the product and sets the test procedure. Depending on the brand that is purchased, there may be some variations, the important thing is that we refer to the levels of sensitivity or specificity that the test must give”Escalante specifies.

“We make a large call for these swabs and not necessarily a single company has the required amount. We can have several brands and as they come in we distribute them, but it is not that we select who we give it to because all the tests work well.”, he indicated.

Does the effectiveness depend on the depth of the swab?

As to whether the effectiveness of these tests (molecular or antigen) depends on the depth at which the swab is inserted into the nostril, Escalante points out that it does not necessarily.

“It has nothing to do with it, what happens is that each of the tests uses different styles and even now there are commercial tests that are saliva. Each of these tests have been validated under conditions such as swab size, sample depth, and this is what guarantees that the test has good efficiency”Add.

Another factor, not major but very important, is the skill of the medical staff when performing the swab test. “Like any exam, the skill of the medical staff is important. But, we have been doing this type of tests for several years and we do training so that they can take tests correctly.”, indicates Escalante.

Studies

As reported by Bill Gates, in his book ‘How to avoid the next pandemic’, the Seattle Coronavirus Evaluation Network (United States), or Scan, for its acronym in English, ran into local research that ensured the effectiveness of shallow swabs.

“SCAN received a strong accolade from another group of local researchers, who demonstrated to government regulators that spinning a swab from the shallow part of the nostrils produced results just as good as those brain-tickling depth scans that were used in the study. they needed for other COVID-19 tests. This was an important advance, because it allowed people to take their own samples, while the previous system required the intervention of a health professional″, mentions the aforementioned book.

How to correctly take a swab test (nasal or nasopharyngeal)?

Nasopharyngeal swab

• Explain to the patient the procedure to be performed. (The staff should consult the patient if they have a runny nose and suggest cleaning the nostrils).
• Position the patient’s head at a 70° angle looking up. In the case of minors, the father, mother or guardian must hold the head and arms of the minor.
• Ask the patient to place their mask below the nose, holding it by the elastic bands and covering the mouth or, failing that, use tissues or paper towels to cover it
• Introduce the swab gently into one of the nostrils, sliding it along the floor of the nostril until it touches the posterior wall of the pharynx.
• Gently rub the pharynx by rotating the swab and leaving it in for about 10 seconds, or as indicated on the insert.
• Do not insert the swab upwards, following the shape of the nose;

nasal swab

• Explain to the patient the procedure to be performed. (The staff should consult the patient if they have a runny nose and suggest cleaning the nostrils).
• Position the patient’s head by lifting their chin at a 70° angle.
• Ask the patient to place their mask under the nose, holding it by the elastic bands and covering the mouth or, failing that, use tissues or paper towels to cover it
• Insert the swab through one of the nostrils, approximately 1 to 2.5 cm deep.
• Rub the wall of the nostril, performing rotations for about 10 to 15 seconds.

Where are tests to rule out COVID-19 carried out?

COVID-19 drop off points

If you are in Lima or reside in any region of the country, you can access https://www.gob.pe/puntoscovid and check your nearest disposal point.

Remember that molecular tests will be taken from people with comorbidities and adults over 60 years of age, while antigenic tests will be applied to people with symptoms of the disease. coronavirus.

In the case of people without symptoms and without comorbidity who have had contact with a person infected with COVID-19they must call 113 to receive teleorientation.

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