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Tuesday, September 22 2020

How To Interpret COVID-19 Test Result?

Due to the COVID-19 pandemic, there has never been a more urgent call for testing than today. The head of the World Health Organization (WHO), Tedros Adhanom Ghebreyesus, urges all countries to "test, test, test". It is considered among the "backbone" or most crucial elements of our global response to the virus. Thus, making testing for COVID 19 one of the most sought after commodities around the world.

Testing identifies the infected people, making it easier to isolate them and conduct contact tracing. These three steps are also key to reducing the spread of the coronavirus. Additionally, COVID-19 testing provides insight into the regional and national infection rate so that appropriate public health interventions may be put in place.

However, even after months of dealing with the COVID-19 pandemic, there are still questions and unclear information about test results and their interpretations. In this article, we will bring light to this and discuss how to interpret COVID-19 test results.

COVID-19 Test Overview

You should first understand that no test is perfect. All tests can result in a possible false-positive result. Meaning, the test can turn out positive even when you don't have coronavirus. It can result in a false-negative too where it comes back negative even when you do have the COVID-19 virus. There will also be times where the results are not clear or when you're not sure whether it's positive or negative. This is why results should only be reviewed by health care professionals.

Currently, the State and your local public health departments are responsible for making decisions about testing for COVID-19. For the latest information on testing, you can find your State Health Department Website here or your Directory of Local Health Departments here.

If you deem it necessary, there are available testing sites all over the country where you can get yourself tested. You are recommended to undergo coronavirus testing if you belong to any of the following groups of people:

  • Symptomatic people and those identified through contact tracing.
  • Those over 65 and people with underlying conditions.
  • Front liners or those who can't practice social distancing. For example, health care workers, grocery store workers, mass transit workers, etc.
  • Those living in a confined place such as prisons, retirement homes, etc.
  • Those who will undergo medical procedures or people who are hospitalized.

Now, when it comes to COVID-19 tests, there are two kinds: viral testing and antibody testing. Antigen test will be introduced soon. To give you an idea, viral testing involves a nasal swab or saliva test and it can detect a current COVID-19 infection. Antibody testing, on the other hand, requires health care professionals to sample your blood. This test can only detect recent and past infections. For more information about the two types of tests and their results, continue reading below.

 

Two Kinds of COVID-19 Test

 

Viral Testing

The complete genome of the coronavirus was already available in the early stages of the epidemic. This allowed facilities to develop tests in detecting viral RNA. Soon, tests using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) were developed. This method can target the presence of the viral RNA and it can detect the SARSC-CoV-2 virus which causes COVID-19.

Aside from testing for a virus' RNA, viral testing can also include testing for its proteins or also known as antigen testing. However, this type of test is less sensitive. So if you got this test and it came back negative, ask a health care provider if you need to test with RNA too and how long you should stay at home.

How does it work?

This type of test requires a sample that is usually obtained by a nasopharyngeal swab,or nasal swab. During this process, a 6-inch long swab or a giant Q-tip is inserted in your nostril to reach the cavity between your mouth and nose. This is done for 15 seconds with the swab rotating several times. After, this will be repeated on the other nostril to ensure there's enough sample collected. To determine the result, the sample will be tested through a pre-made kit. Very recently, a saliva based molecular test was introduced as an alternative to nasal swabs. Participant coughs three times and then provides saliva for the testing kit. However, remember that viral testing only informs you of a current infection. It can't tell whether you have had the virus before.

Antibody testing

When a virus like the SARS-CoV-2 invades your body, your immune system automatically does its job and fights it off. Eventually, your body will start to send out many Y-shaped molecules that target that specific virus - these molecules are called antibodies. Now, a test was developed to detect if a person has these specific antibodies against coronavirus.

How does it work?

Generally, there are two types of antibody tests used for COVID-19: the Lateral Flow Immuno-Assays and Enzyme-linked Immunosorbent Assay (ELISA). However, they both use the same principle which is getting a sample of your blood or serum and checking for your body's immune response to the virus. These COVID-19 testing methods indirectly detect Immunoglobulin A (IgA), and Immunoglobulin M (IgM).

Their difference is that the Lateral Flow Immuno-Assays can be run quickly by Medical Professionals. On the other hand, ELISA tests require technicians to run it in a lab.

Antibody testing is the opposite of viral testing and it can tell you of a recent and past infection. Take note, however, that according to the Centers for Disease Control and Prevention (CDC), it usually takes one to three weeks after infection before your body can make antibodies. So this type of test may not show you if you are currently infected. This is why it's not used for diagnosis.

Interpretation:

1. Viral Test Interpretation

  • Positive: If your test result is positive then this means that you most likely do have a current active COVID-19 infection. This also means that you can give the virus to others.
  • Negative: If your test results turn out negative, you most likely do not have a current active COVID-19 infection. 

2. Antibody Interpretation

  • Positive: If your antibody test turns out positive, this means that you have likely had a COVID-19 infection. 
  • Negative: On the other hand, if it turns out negative, it means that you've likely never had or have not yet developed antibodies to coronavirus infection. 

3. Both

  • Viral Positive and Antibody Positive: If you've taken both tests and they turn out positive, you most likely have a current and active COVID-19 infection. You can also infect others.
  • Viral Positive and Antibody Negative: You most likely have a current and active COVID-19 infection and you can give it to others.
  • Viral Negative and Antibody Positive: You likely had coronavirus but you have already RECOVERED from it.
  • Viral Negative and Antibody Negative: You likely never had a COVID infection.

 

Recommended Action

  • Viral Testing

If you have tested positive in a viral test, you are required to stay home and avoid public places and transportation except when you need to get medical care. Most people who are infected by COVID-19 have mild cases and can recover at home. Just get enough rest and always stay hydrated. You can also use over-the-counter medicines like acetaminophen to feel better. While at home, isolate yourself and stay in a specific room away from other people and pets. If possible, use a separate bathroom as well.

You should also stay in touch with your doctor. If you are having trouble breathing, feeling a persistent pain or pressure in your chest, having bluish lips or face, not able to wake up or stay awake, or other emergencies, call 911 or call your local emergency facility. (Don't forget to notify them that you are seeking care for a COVID-19 patient.)

  • Antibody Testing

On the other hand, if you tested negative but showing some symptoms, continue monitoring yourself. You can seek medical advice if you need to get tested again. But if you're not showing any signs of infection, you don't have to take the test again unless a medical provider or your workplace tells you to.

For an antibody test, having a positive result may result in developing some protection from re-infection. However, this can't be said with certainty. While it might give you some protection from getting infected by the virus again, there's no data and information just yet on how much protection the antibodies provide and for how long it can last. However, there were very few cases of people getting re-infected.

If your test result is negative, you could still get coronavirus. Or you could still have a current infection. Remember, the test can only detect antibodies after 1 to 3 weeks after infection. So if you've been exposed to the virus recently, you can still spread the virus. Also, take note that some people may take longer to develop antibodies so 1-3 weeks may not be enough. Moreover, some people who were infected may never develop antibodies.

 

Conclusion

If you notice any symptoms of the virus, you should get the Viral Test. If you have been infected and recovered, only then will you be recommended to take an Antibody Test. But remember, whatever result you get by testing for COVID 19, you are encouraged to follow basic guidelines - cover your mouth and nose with a face cover around others, social distancing, and frequent washing of hands.

If you think you need to get tested for COVID-19, there are many available testing sites. There are academic, commercial, and private laboratories that conduct COVID-19 testing all over the country. If you are looking for a reliable testing service that you can trust, Workplace Screening Intelligence (WSI) is here for your coronavirus testing needs. For more information about our available testing for COVID-19 methods, give us a call at 800-338-5515 or email info@workplacescreening.com

Posted by: Phil Dubois AT 09:11 pm   |  Permalink   |  Email