Which Type of Test Is Best for Covid-19

17,Dec,2020

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All over the world, steps have been taken to control the virus and its spread. While this has worked and is working, measures are still being taken to prevent its spread and another lockdown. Testing for the coronavirus is quite a process as there are several types of tests available, which can cause some confusion. The issue here is finding the best test for COVID-19 detection.

Which test to use

As of now, some tests test for current infection, and others check for past infection. However, there is still information about the test we don’t know, and the options for the testing keep changing.

Diagnostic test for current infection

If you are interested in finding out if you are currently infected with the COVID-19 virus, there are two test types you can choose from. They are the molecular test for COVID-19 and the antigen test for COVID-19.

Molecular test for covid-19

This test is also called viral RNA test, nucleic acid test or Pcr test

Where you can get this test: You can get this type of test done in a medical office, hospital or even at home by yourself.

Collection of samples: Samples for this type of test is collected through a saliva test, bodily fluids, nose swab or throat swab.

What the test looks out for: This type of test looks out for genetic material that comes only from the virus

How long before you get results: The total amount of time before you get your results from this type of test is dependent on the laboratory capacity. Usually, results for COVID-19 tests take about a day or two, but the results of this test can be available on the same day. Lately, however, there have been several reports that test results have been delayed for a week or two in some places.

Accuracy level: There is a low chance of about 2 – 37% where you can get a false negative result. A false-negative result is a situation whereby your test results say you don’t have the virus; meanwhile, you do. The chances of getting a false-positive result are closer to zero and are mostly as a result of contamination of the samples or some other problems from the lab and not the test itself. A false-positive result shows you have the virus when you don’t. There are fewer chances of having a false negative test if a deep nasal swab is taken as a sample.

There is also a situation called a pooled testing, whereby multiple samples are combined, and molecular testing carried out on them. If the test comes out negative, there would be no need for individual testing, however, if it comes out positive, each of the samples would have to be retested to find out which one carries the virus. This approach is beneficial as it tests multiple people at once, thereby reducing testing time.

Antigen test for covid-19

Where you can get this test: You can get this type of testing at a hospital, doctor’s office or a blood-testing lab

Collection of samples: The sample required for this test is your nasal or throat swab

What the test looks out for: This test looks out for protein fragments or antigens from the virus

How long before you get results: Due to the technology used in this test, you can get your test result in a matter of minutes, much like pregnancy or rapid strep test.

Accuracy level: Antigen test is not favoured by the FDA, due to its 50% high rate of a false-positive result. However, because it is a quicker and less expensive type of testing, multiple testing is recommended for a more stable result. Recently, the false-positive result rate of the testing type is near zero.

Diagnostic test for past infection

Antibody test

This test type is also called serological testing, and while it cannot tell if you are currently infected, it can accurately detect a past infection.

Where you can get this test: In a hospital, doctor’s office or a blood-testing lab

Collection of sample: The sample needed for this test is your blood sample

What the test looks for: This test looks out for antibodies that have been produced in response to an infection by the virus

How long before you get results: Results are usually available within a few days

Accuracy level: The rate of false-negative for this test is about 0 – 30%. However, having this type of test too early can give false-negative results because it takes about two weeks before the immune system produces antibodies in response to an infection. The rate of a false positive test is about 20%

How accurate are these tests?

The true accuracy of these tests are not certain for the following reasons

• Result accuracy can be affected by the collection and storage of samples
• There is no definite gold standard test to compare them to
• There are no precise measurements for accuracy for any of these tests, just commonly quoted figures for false positive or negative results
• Accuracies may vary due to a large number of laboratories and companies offering the test
• None of the tests is officially approved by the FDA; they are available because the makers have been granted authorisation because of emergency use
• The testing methods are new because the virus itself is new.

Getting a test for COVID-19 can be confusing; however, you can still get tested at certified hospitals and laboratories. Visit our Walk in Clinic or click here to book a PCR antigen test.