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6 Key Questions About Diagnostic Tests for COVID-19, by Elmer Huerta

The omicron variant continues its unstoppable advance across the planet. In Peru, data from the National Center for Epidemiology and Disease Control (CDC) confirm that 21 of the 24 regions of the country have seen an exponential increase in cases of COVID-19 in the last two weeks. Although there are no confirmatory genomic data, the delta variant – the predominant one to date – does not have this behavior, so it is very possible that this explosive increase is caused by the omicron variant.

So far, in addition to having documented that it is three times more contagious than delta and that it is capable of infecting people who have been vaccinated or who have previously suffered from the disease, it has also been seen that omicron causes a mild illness in vaccinated people. In this regard, the Ministry of Health of Spain has reported than unvaccinated people ages 60 to 80 are 25 times more likely to die from COVID-19.

The massive number of infections is causing many people to want get tested to confirm that they are infected. Today we will see what those tests and their main indications are, and above all we will emphasize that the tests are in no way life-saving.

People who should be tested fall into two main groups: those who develop respiratory symptoms (symptomatic), and those who do not, but are close contacts of the infected (asymptomatic).

There are two main types of evidence to know if the virus is present in the respiratory tract of a person: PCR or molecular, and rapid diagnostic tests (RDT in English), whose main type is the antigen test.

Both have their advantages and disadvantages. PCR, which is the gold standard for being the most sensitive to detect the virus, requires sophisticated technology and is therefore not widely available. In addition, it is expensive and takes several hours to process; that is, your results may take one or more days. The antigen test is much cheaper and faster, and can, like the home urine pregnancy test, give a result in 15 minutes.

“The people who need to be tested fall into two main groups.”

None diagnostic test for him COVID-19 it’s 100% perfect. These are evaluated for their ability to correctly identify positive cases in groups of infected people (sensitivity), and to correctly identify negative cases in people who do not have the infection (specificity).

The sensitivity of PCR is about 95%; that is, only in 5% of cases does the test yield a negative when it is actually positive (false negative). For its part, the antigen test (especially when the person has no symptoms), only manages to hit the positivity 40 to 70% of the time; in other words, the false negatives can be very high.

In general, knowing the limitations of the aforementioned tests, it is advised that symptomatic people with a high viral load choose the proof of antigens, being faster and cheaper, while PCR tests are more useful for asymptomatic contacts, with lower viral load.

As mentioned, there are two groups of people looking for a proof: those symptomatic who want to know if they have COVID-19, and the asymptomatic ones, who suspect they have been infected.

Knowing that COVID-19 does not have specific medical treatment, the main purpose of taking the test is – in the case of a positive result – to monitor the symptoms of the disease and initiate protection measures for the family and society: use masks and isolate for 14 days in Peru.

Given the shortage of evidence, and knowing that its result does not imply the initiation of a specific treatment against the COVID-19, many people wonder if a test is mandatory. The answer is that, although it is true that the test is desirable to keep the statistics of a country up to date and for the emotional tranquility of a person, it is not absolutely necessary.

This is because when they suspect that they have been infected or when they start respiratory symptoms, the person must, while looking for a test, assume that they are infected and initiate the recommendations that they will give them anyway if the positive test comes out: immediately notify their close contacts about your situation, start using KN95 masks and isolate yourself for the days that the country’s regulations regulate.

“No diagnostic test for COVID-19 is 100% perfect.”

–Disruption of society–

It is possible that, like It is being seen in the United States, where the enormous number of infected people in isolation is causing a collapse of basic services (medical, transportation, garbage collection, etc.), Peru will see a serious disruption of society in the coming weeks.

To avoid this social collapse, the Ministry of Health (Minsa) must update its standard for isolating suspected and confirmed cases of infection, which is currently 14 days. Analyzing the American model of reducing isolation from ten to five days, asking for a negative test on the fifth day and returning to work with a mask, is one option. Another is the model they use in Argentina, UK and Spain, which also consists of reducing their isolation period from ten to seven days. That decision is urgent, having hundreds of thousands of people on medical rest for a minor illness can be counterproductive.



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