Covid-19 Test Results Meaning: PCR Vs Antigen Covid-19 Tests
Most of us have been tested for Covid-19, but do you know which of the tests you got? There are two main tests for Covid-19, diagnostic and antibody tests.
Diagnostic Covid-19 tests are used to detect if one has an active Covid-19 infection. On the other hand, a Covid-19 antibody test is done to assess if you have had Covid-19 in the past and whether your body has antibodies that can help fight the virus. Another difference between the two is that Covid-19 diagnostic tests use throat or nasal samples, while antibody tests require a blood sample.
The two commonly known diagnostic Covid-19 tests are the PCR and the lateral flow test. In this article, we will focus on these two tests, and we are also going to find out the antigen and PCR Covid test meaning and what the test results of the two tests mean.
Who Should Get Tested for Covid-19
According to the NHS, anyone who has been exposed to the SARS-CoV-2 infection should get tested even if they’re asymptomatic. Another category of people that should get tested is those that show Covid-19 symptoms.
Some of the symptoms to look out for include:
An ongoing cough;
Fever or chills;
Loss or change in smell and taste;
- Difficulty breathing or shortness of breath;
- Body aches;
- Nausea or vomiting;
- Sore throat;
- A runny nose or congestion.
The NHS recommends taking a PCR test if you have Covid -19 symptoms. If you’re asymptomatic and you suspect you might have a Covid-19 infection, the best test to take is a rapid lateral flow test.
What Is a PCR Test?
The polymerase chain reaction (PCR) test uses the polymerase chain reaction technique to test for a Covid-19 infection. The test detects the coronavirus genetic material or RNA in a sample.
The first step during a PCR test is sample collection which is done using a swab. The throat or nasal swab is used in the nasal or throat area to collect the specimen. The sample is then treated with an enzyme that converts its genetic material or RNA into DNA. The DNA is then mixed with a polymerase which is an enzyme that helps separate the double-stranded DNA into single-stranded pieces.
With the help of a primer, the single-stranded coronavirus DNA is amplified or copied. This process is repeated until millions of copies of the original DNA are made. The copied sequence has a fluorescent dye that changes colour if the SARS-CoV-2 virus is present in the sample.
What Is an Antigen Test?
An antigen test, commonly referred to as a rapid lateral flow test in the UK, is a quicker and easy-to-use test that helps detect the presence of an active infection. It’s common to see lateral flow test for sale online and from private pharmacies as this test is very affordable.
The rapid lateral flow test has been used in the UK in the past as the NHS test for mass testing to help contain the spread of the Covid-19 infection.
Antigen tests work by detecting unique proteins, also called antigens, on the surface of the virus. During the test, a sample is collected from the nasal or throat area and dipped into an extraction liquid. The mixture is then dripped onto a test strip that has antibodies that are specific to the coronavirus. If the sample has the SARS-CoV-2 virus, the antibodies will bind to the coronavirus antigens present in the sample.
A coloured line will then appear on both the control and test lines of the test strip. The Covid-19 test meaning of this result is that there is the presence of the Covid-19 virus in the sample. You can also get negative antigen test results meaning that you don’t have an active SARS-CoV-2 infection at the time of the test. In such a case, the coloured line will only appear on the control line and not on the test line.
The test results of the rapid antigen test are visible within 15 to 30 minutes.
What’s the Difference Between the PCR and Antigen Tests for Covid-19
One of the key differences between the PCR and the antigen test is how they work. The two tests work very differently as the PCR test is used to detect the genetic material that is unique to the SARS-CoV-2 virus in a sample. On the other hand, the antigen test detects certain proteins or antigens that are unique to the Coronavirus in a sample.
The PCR test is highly sensitive as it can detect even the smallest amount of the SARS-CoV-2 virus RNA in a sample. With a sensitivity and accuracy that approaches 100%, the PCR test is recognized as the gold standard for Covid-19 testing.
The PCR test is best used in the early stages of the Covid-19 infection as it can detect even a small amount of the virus in a sample. PCR Covid-19 tests are also used to confirm negative rapid lateral flow tests in symptomatic persons.
However, PCR tests, despite their high sensitivity, have weaknesses. For starters, they require skilled personnel and special lab equipment for test analysis. The test analysis process also takes a long time, meaning it can take up to 24 hours or a few days before you get the result of the test. PCR tests are also expensive. The sensitivity of the test also means that it can give false positives if it detects the presence of the SARS-CoV-2 virus in a sample of a person who is healed and is no longer contagious.
Lateral flow tests such as the Healgen antigen test kit have several strengths, including the fact that they’re easy to use and can be used on the go. Besides, unlike PCR tests, rapid lateral flow tests do not require skilled healthcare workers or to be taken to clinical laboratories, making them suitable for home testing. They also give results quickly and are very affordable.
Rapid antigen tests aren’t as sensitive as PCR tests. LFTs are most effective when used to detect a Covid-19 infection in a person with a large amount of the virus in their body. This also means that, unlike the PCR molecular test, lateral flow tests can miss a Covid-19 infection in the early stages of infection.
PCR test is the recommended test for people who have been in self-isolation and may want to know if they’re still infected or contagious. Having two negative antigen test results two days in a row is another reliable sign that one is no longer infectious.
In closing, understanding the differences between PCR and rapid antigen tests is important as it helps you know the best situation to use each of the tests.
Hopefully, now you know the meaning of each of the tests and the Covid-19 test results meaning for both tests.
If you need a rapid lateral flow test for home use, you can buy a FlowFlex Covid test from CovidTests. Talk to us today for more information on how to get your test.