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What Is A Rapid Antigen Test And When To Use It

A rapid antigen test, often referred to as a rapid COVID-19 test, is actually a viral test. It is one of the two main types of tests that are used for detecting COVID-19. Rapid antigen tests are accepted as one of the quickest and simplest methods to get tested for COVID-19. The tests are recommended by not only many health professionals but also governments, as a viable and cost-effective method of mass testing people. 

Let’s review the basics of this type of test, how accurate it is, how it works, and where you can find a trustworthy and reliable source for this test. 

What Does ‘Antigen’ Mean?

Harvard’s Medical Dictionary of Health Terms describes an antigen as any substance that your body recognizes as foreign or harmful, which prompts your immune system to produce antibodies to fight it. 

How Rapid Antigen Tests Can Identify COVID-19

Rapid antigen tests are able to identify the protein fragments present on the surface or within COVID-19 virus and can thus detect the pathogen’s presence in people taking the test. Samples are obtained by swabbing inside the throat or nose of subjects. 

How Antigen Tests are Administered

These tests are usually administered by taking samples from inside your nose or from your nasopharynx, which is the top part of the throat that is behind the nose. The test sample is taken using a sterile cotton swab that is inserted into your nostril and then adding a buffer or testing solution for arriving at a result. 

Let’s briefly look at the steps involved in the procedure:

  • Collect the sample by placing the swab inside the subject’s throat or nasal wall
  • Put the swab into the test tube so it is submerged in the testing solution
  • Add the buffer or testing solution to the test strip
  • Wait for about 15 minutes for the result

Are Antigen Tests Reliable and Accurate?

The reliability or accuracy of rapid antigen tests is often questioned. In comparison to the polymerase chain reaction (PCR) test, rapid antigen test is somewhat less accurate. 

Usually, the accuracy of a test is measured using specificity and sensitivity. Let’s look at what these terms mean:

  • Specificity refers to the ability of a test to correctly determine that the subject does not have COVID-19
  • Sensitivity refers to the ability of a test to correctly determine that the subject has COVID-19

It’s proven that PCR tests’ analytical performances, both sensitivity and specificity, are  near 100%, even though the accuracy varies by test due to biological factors such as where the virus is present, how much virus is present, and time from symptom onset . There have been cases of some tests producing false negative results. 

By comparison, antigen tests have evidenced the sensitivity of antigen tests is 30% to 40% lower than for PCR, depending on whether tested subjects were symptomatic or asymptomatic. 

Just to explain, a false negative means a subject is erroneously diagnosed as not having the disease. So, for instance, let’s say that someone who has COVID-19 takes a test. If the result of the test is negative, although the subject is infected, it would be considered as a false negative result. This is because the test fell short of correctly identifying the person with the coronavirus infection. 

What Are Antigen Tests Used For?

Rapid antigen tests are used for identifying people that currently have COVID-19. There are other tests that can identify subjects who previously had COVID-19, but are not infected now. 

Aside from being used for detecting COVID-19, this technology is also commonly used by medical facilities for identifying:

  • Malaria
  • The influenza virus
  • Streptococcus infections

COVID-19 Antigen Test: Pros and Cons - Below are some of the pros and cons of antigen tests:

  • Speed: A striking benefit of the antigen test is the short time in which it returns the result. In contrast, the standard reverse transcription polymerase chain reaction (RT-PCR) test takes a much longer time. The rapid COVID-19 test just requires adding the sample to the testing strip and a waiting period of not more than 15 minutes for the result.
  • Cost: Rapid antigen tests are not as expensive as other types of tests
  • Convenience: You can test yourself from the comfort of your home – without requiring personal protective equipment. In fact, you are not required to undergo elaborate laboratory training due to the simplicity of the testing procedure. 
  • Accuracy: Unfortunately, the results are not as accurate, although the underlying technology continues to improve. If the test result comes out as negative, with clinical symptoms persisting, additional testing using different methodologies such as RT_PCR would be called for. A negative result does not guarantee the subject is free of SARS-COV-2 infection. 
  • False Positives: Medical experts tend to view positive antigen tests as relatively more accurate. However, this not to downplay the fact that false positives may occur. The concern is that other viruses may be responsible for the false positives. Alternatively, faulty collection techniques, or other bodily substances may also skew the results. 

When Should You Use a Rapid Antigen Test?

A rapid antigen test kit, with which you can perform the test at home, is a smart addition to your arsenal against COVID-19. However, it is important to know when you might use this type of test.  

If You Have Symptoms:

If you happen to have COVID-19 symptoms, you can take this at-home test. If the test result turns out to be positive, it is almost certain that you have the infection. 

However, if you test negative despite having the symptoms, it would not be safe to dismiss the possibility of COVID-19 just yet. Instead, it would be better if you went for the PCR test, which is more sensitive. But if you are unable to take a PCR without considerable delay, you might want to repeat the antigen test next day, making sure to isolate yourself in the meantime until you can take the PCR test and get the result. If it is absolutely not possible for you to get a PCR test, stay isolated for at least 5 days; continue to follow precautions through day 10.  

If You Are Asymptomatic:

In case you do not have any COVID-19 symptoms, using this test before attending a social event will lessen, but not eliminate, the risk you might pose to others. Remember that antigen test results may change quickly, and a negative result can be considered valid only for no more than 24 hours. 

With that said, for example, you should not interpret a negative test you got today as sufficient reason to get together with friends or family the next day. Also, make sure that everyone attending the event takes the antigen test as close to the time of the get-together as possible, and they should also realize that a negative test is no guarantee of safety and that neither does the test prevent exposure completely.

Where Can You Get a Rapid Antigen Test?

Project Screen offers the FlowflexTM COVID-19 Rapid Antigen Test which is approved by the Hong Kong government, is highly accurate, and authorised by over 40 governments worldwide. It’s the most accurate rapid antigen test on the market for Omicron variant detection, based on an independent validation study by University of Geneva, Switzerland with support by the Swiss National Science Foundation. Furthermore, the test outperformed all rapid antigen test kits in the Independent Nationwide Clinical Sensitivity and Specificity Study led by Copenhagen University Hospital, Denmark comparing 46 different tests, and achieved 94% sensitivity and 100% specificity.

You can get the FlowflexTM COVID-19 Rapid Antigen Test on the Project Screen website today in kits of 1, 5, and 25. 

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