How Reliable Are PCR Tests for Covid-19 – 2024 Guide


The Polymerase chain reaction is a lab-based technique. In this technique, we use selective primers that copy specific DNA segments and amplify them. These primers are basically something that has similar genetic material to the virus. So the virus and primers will have the same genetic makeup.

What does PCR do?

Polymerase chain reaction results in creating many copies of the material. Thus, we become able to detect the presence of the selected virus.

The polymerase chain reaction is a test that we have been using for a long time now. Therefore, as soon as the Coronavirus came to the world, we used the same test for it too. It shows whether the virus is present in the body of the tested person or not.

A positive report confirms the presence of coronavirus. A negative result is because is two reasons. Either the virus is too weak to detect, or is not present in the body.

So if you are worried about being infected with coronavirus, you can take a PCR test. You can get yourself tested at NorthShoreClinical they have separate Covid-19 services that you can get without getting through any trouble. You can contact them through their website or go to their walk-in clinic.

How does this work for Covid-19?


Although the PCR technology is the same, however, for testing the presence of coronavirus, there is a change. Our laboratories use a modified version which we know as “Quantitative polymerase chain reaction”. This method gives us quantitative results.

In this method, a fluorescent dye is used to calculate the quantity of the present virus. Thus, even with a negative test result, we will be able to tell whether there is a weak quantity present or not.

A positive test report

If you get a positive test report, it means you have Covid-19. The primers never create new viruses. Instead, they only amplify the already existing ones. Therefore, only the present viruses are counted and measured. So if you have a positive report, it clearly means that you have enough virus in your body.

A false-positive result

Even if the virus is not present in the body, sometimes errors can occur and the report shows positive signs. This is what we call a false positive. The best way is to get another test to confirm the authenticity of the report.

A negative test report

A negative report shows that the sample was free from any coronavirus. And therefore, it did not get any results. So you can rest assured.

False negative

The third category is a false negative. This is what makes people doubt the reliability of the PCR testing technique. A false negative report means that although you are infected but the genetic material of the virus is too low to be detected. This usually occurs during the beginning of the disease when the body has just been infected.

Why do people question the credibility of the PCR test for Covid-19?


The question the people raise about the credibility of PCR tests is because of the quantitative approach. Although regular PCR tests only measure the presence or absence of viruses in the sample but we have qPCR too. A regular PCR test will give a negative result if the quantity of the virus is too low in the sample.

However, the virus may multiply in the future and results in severing the disease. And just because you already had the test report, you won’t think that you are suffering from Covid-19. As a result of this, you will not take the other medicines and keep on relaying the ones that are not for the coronavirus.

These are the reasons to question the effectiveness and reliability of PCR tests.

But is it just like that?

No, it’s not.

Testing laboratories actually use the quantitative polymerase chain reaction. This process involves a dye that colors the virus. As a result of this, we can have quantitative results. So even if the number of viruses is too low, we will at least know about it.

The quantitative approach helps the paramedics to tell whether the virus is deadly or not. For example, your doctor will ask you about the symptoms. If you have just started to feel ill a few hours ago, it means that the virus has just entered your body and is in the beginning stage. Therefore, you need to take care of yourself for the next weeks. In addition to this, your doctor will also prescribe the medicine for you.

However, if you have been ill for a week now and suddenly the thought came to you if you have corona, you should still take the test. Coronavirus shows mild to severe symptoms depending upon the health and immunity of the individual. Therefore, even if you had mild symptoms and they did not last for a long time, you might still be infected with the Covid-19.

So if you get the test while you are recovering, the quantity of the virus will still be less. So if you are in your recovery period, you can just take a better diet to maintain your good health. If the symptoms were mild, it means that you have stronger immunity. Therefore, your body was able to fight the viruses.

The safe way


If you have any doubts regarding the test report, you can take another test. This is the safest way for you. If you fear a false positive or a false negative report, you can discuss it with your doctor. He can suggest you take another examination. The time between the two tests should also be noted. Whether you should take the test after 24 hours or 48 hours, the doctor will let you know.

Final words

The PCR tests are quite reliable and therefore, they are being widely in use. Just to prevent a false test report, it is better to take another test after a few days. But again, this is just for your confirmation if you feel ill.