The Difference Between PCR and Antigen Tests

COVID-19 testing is now a regular part of life for many individuals
across the country. As the Omicron variant emerges as the dominating
strain of the SARS-CoV-2 virus, the unvaccinated and vaccinated alike
are relying more and more on weekly (sometimes daily) tests to work,
travel, or generally engage with the community.

Horizon Laboratories is dedicated to offering our patients the best
healthcare options available. As of January 2022, there are two broad
categories of testing available to the public: PCR tests and antigen
tests. They are both considered ‘diagnostic tests,’ which means either
will be able to tell you if you are currently infected with the
coronavirus at the time of testing.

While department of health guidelines on isolation and/or quarantine will continue to
evolve, understanding how these tests work is information to be aware
of. A lot of our patients want to understand: What is the difference
between PCR and antigen tests?

 

WHAT IS AN ANTIGEN TEST?

covid-19 antigen test cassette

According to Harvard Medical School:

“Antigen tests detect specific proteins on the surface of the coronavirus. They are sometimes referred to as rapid diagnostic tests because it can take less than an hour to get the test results. Positive antigen test results are highly specific, meaning that if you test positive you are very likely to be infected.”

Antigen tests, while offering results within 15-30 minutes with great accuracy, can return a higher rate of false negatives than the PCR test. Once infected, a patient ‘sheds’ the viral load in their system; these levels can vary widely over the course of infection. Test too early (or too late) and it may result in a false negative – but, antigen tests will detect active infection. Antigen testing is still widely regarded as the primary line of defense because they offer results in minutes, doesn’t require laboratory processing, and costs less out-of-pocket. we  can even perform antigen tests at home or at Events.

WHAT IS A PCR TEST?

Covid-19 PCR test

“A polymerase chain reaction (PCR) test is performed to detect genetic material from a specific organism, such as a virus. The test detects the presence of a virus if you are infected at the time of the test. The test could also detect fragments of the virus even after you are no longer infected.”

PCRs determine whether the virus is present by looking for the presence of the virus’s genetic material. Most of the time, PCR tests are extremely accurate; the only drawback being the amount of time between getting tested and getting a definitive answer.

After a sample is extracted (commonly using the deep nasal swab technique, although samples from the throat or saliva may be tested also), it’s sent to a laboratory for processing. Typically, that process lasts anywhere from 2-24 hours.

We’re pleased to offer PCR testing with results in 2-24 Hours.

 

THE DIFFERENCE BETWEEN PCR AND ANTIGEN TESTS

Generally, the differences are technique, time, and usage. The cost often varies too.

  • An antigen test is a rapid test, while the PCR test traditionally takes a few hours to return results.
  • An antigen test looks for specific proteins found on the surface of
    the virus, while a PCR test seeks out and amplifies the presence of the
    virus’s DNA material.
  • PCR tests are preferred/required for international travel.
  • Our price for an antigen test  is R350; for PCR, the test starts from R500 – R1200

We offer both PCR and antigen tests at Horizon Laboratories.

What is the difference between a PCR test and an antigen test for COVID-19?