Skip to Main Content
Antigen vs antibody vs PCR testing

Antigen vs. Antibody vs. qPCR: FAQ about tests for COVID-19

Testing for viral pathogens has become top-of-mind during the COVID-19 pandemic for many people who wouldn’t normally give it a second thought.

As the virus continues to spread, it’s more important than ever to be aware of the tests used in public health responses to viral outbreaks. In this post, we’ll discuss the different types of tests and how they’re used to detect SARS-CoV-2, the pathogen that causes COVID-19.

What kinds of COVID-19 tests are there?

Broadly, there are two categories of tests: diagnostic and antibody. Diagnostic tests are used to determine if someone currently has an active infection while antibody tests can indicate whether someone has had an infection in the past.

Antibody tests aren’t typically used to diagnose COVID-19 because it can take between one and three weeks after infection for the body to develop antibodies. For this reason, diagnostic tests are used to actively detect the virus in populations and individuals.

The two most widely used diagnostic tests are:
  1. Antigen tests, which detect specific proteins from viral pathogens.
  2. PCR tests (which stands for polymerase chain reaction), which examine DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) sequences.

How does an antigen test work?

Antigen tests detect the proteins on the surface of a virus. This method is less reliable, but produces much faster results. Antigen tests are great for mass screening of populations because of their speed and cost but negative results may need to be confirmed with a PCR test.

How does a qPCR test work?

Quantitative PCR testing, or qPCR, is the gold standard for COVID-19 testing because of its accuracy. To conduct a qPCR test, a sample is combined with reagents to produce a fluorescent signal. If the target RNA is present in the sample, its concentration eventually reaches the cycle threshold where it’s detected by the fluorescent signal to accurately diagnose a COVID-19 infection.

The result produced by a qPCR test is the most reliable of any diagnostic test for COVID-19 because it can detect very small amounts of the virus.

How and where are these tests used?

The different types of tests each have benefits and drawbacks that make them more suitable for some applications than others.

Environmental testing—the testing of surfaces and wastewater—is done using the PCR method. This ensures a reliable result is achieved when testing for the presence of SARS-CoV-2 in populations or environments.

Diagnostic testing, or testing for individuals, employs a combination of PCR and antigen tests. If you go to a hospital or clinic to get tested for COVID-19, you will most likely receive a qPCR test. Most rapid and popup testing facilities, however, use antigen tests.

What are the differences between qPCR, antigen, and antibody tests?

ComparisonqPCR TestAntigen TestAntibody Test
What sample is used in the test?Most common: Nasal or throat swab
Emerging alternatives: Saliva, Saline Rinse
Most common: Nasal or throat swab
Emerging alternatives: Saliva, Saline Rinse
Blood sample
What does the test measure?The presence of viral RNAThe presence of viral proteinsThe presence of antibodies
What does the test determine?Diagnoses active infection of COVID-19Diagnoses active infection of COVID-19Shows past infection of COVID-19
How accurate are the test results?Highly accurate, gold standard method for clinical diagnosticsAccurate positive results but negatives may need to be confirmed with a qPCR testPossibility for the need of a second antibody test for accurate results
How long does it take to get results?Under 2 hoursUnder 1 hourUnder 1 hour

LuminUltra Team

Founded in 1995, LuminUltra is a molecular biology diagnostic testing company headquartered in Canada with operations in 6 countries. It is widely recognized globally as a leader in developing tests and reagents for environmental, industrial, and diagnostic monitoring applications and was a key supplier of COVID-19 diagnostic testing reagents to the Government of Canada.

Dozens of Fortune 500 customers across more than 80 countries trust LuminUltra’s technology, production reliability and history of customer service excellence to deliver their essential services in a safe state.

Related Posts

LuminUltra Technologies Ltd.

Introducing our complete COVID-19 clinical solution

LuminUltra Technologies Ltd. is proud to announce that we’ve submitted our GeneCount® COVID-19 RT-qPCR Assay Kit to the U.S. Food and Drug Administration for Emergency Use Authorization and Health Canada for an Interim Order. With this authorization we’ll be able to provide testing facilities throughout North America with a complete, customizable clinical COVID-19 testing solution. … Continued
LuminUltra Headquarters

LuminUltra Will Supply 500,000 COVID-19 tests per week to Canadian Government

April 15th, 2020 Fredericton, New Brunswick – Canadian biotechnology leader LuminUltra today announced that it will provide 500,000 urgently needed COVID-19 tests per week to the Canadian federal government for use across Canada. In his press conference earlier today, Prime Minister Justin Trudeau announced that New Brunswick-based LuminUltra is ramping up its production capacity to … Continued
Your browser is out of date!

Update your browser to view this website correctly. Update my browser now