How COVID-19 Testing Works

COVID-19 tests have proven to be crucial in measuring the spread of the novel coronavirus (SARS-CoV-2) and helping us better understand how to navigate the current global pandemic. Testing has received a large amount of media attention in recent months, but the information has not always been clear. 

The most frequent misconception is that there is only one kind of COVID-19 test. In actuality, there are two distinctly different types of tests that accomplish two separate goals. Knowing the difference between these tests is essential in helping make the best decisions for the health of you and your family. 

To help clear-up any misconceptions, here is a breakdown of both tests and how each one is used in the ongoing fight against COVID-19.


The Two Different Types of COVID-19 Tests 

Currently, there are two varieties of COVID-19 tests being used by healthcare professionals— viral tests and antibody (serology) tests. 


COVID-19 Viral Tests 

Purpose: Viral tests, such as polymerase chain reaction (PCR) and antigen tests, are used to collect genetic information from a patient to test for the presence of the coronavirus. 



The Process: This test is conducted by a healthcare professional, using a long swab to collect a sample of DNA from the back of an individual’s nose and throat for analysis. The swab needs to go far back in an individual’s nose to collect cells and fluids from along the entire passageway to ensure a viable sample.  

If conducted properly, the process should not be painful, but patients have reported experiencing small amounts of involuntary tears and discomfort.

Turnaround Time: The majority of viral tests require further laboratory analysis, and results may take anywhere from three days to a week to receive.

Interpreting the Results: The test results are fairly straight forward. A positive result indicates that there is a viral infection present in the sample, while a negative result indicates that no active infection was found. 

It is important to note that an individual can still test positive for the virus while feeling perfectly fine. Due to the delayed nature of the coronavirus infection, the virus can often take up to two full weeks to exhibit any symptoms.  


COVID-19 Antibody Test

Purpose: Antibodies are proteins in your body that help fight infections and provide protection against getting that same infection again, more commonly known as immunity. An antibody test shows if an individual has developed the antibodies necessary to combat a COVID-19 infection. 



The Process: 

A healthcare provider conducts the antibody test by doing the following three steps:

  1. Collect a single drop of blood from an individual’s fingertip (similar to a glucose test)
  2. Mix the the blood with a special reagent included in the antibody test kit
  3. Add the blood/reagent mixture into the test cartridge and await results

Turnaround Time: The entire process, from the moment the single blood droplet is collected to the final result, takes just 10 minutes.  

Interpreting the Results: Unlike the viral test, which only detects the presence of an active COVID-19 infection, the antibody test is designed to look for two specific antibodies: IgG and IgM

IgG Antibodies 

IgG antibodies develop in most patients within seven to 10 days after symptoms of COVID-19 begin and remain in the blood long after the infection has passed. The presence of IgG antibodies indicates that an individual may have had a COVID-19 infection and developed a long lasting immune response against future infection. 

IgM Antibodies

IgM antibodies are the first antibodies produced by the immune system during an infection. It is developed very early on in the course of a viral infection, in most cases within the first few days. The presence of IgM antibodies indicates that an individual has been infected fairly recently and their immune system has started responding to the virus. Since IgM is quicker to clear the body than IgG, if IgM antibodies are detected in a patient, they may still be recovering from an active COVID-19 infection and should limit their interactions with others.

Once the test is performed, the results are displayed directly on the test cartridge, reading positive, negative, or invalid.



If a person tests Positive for IgG, but not IgM antibodies, there’s a strong chance they have recovered from COVID-19 and have become convalescent. 

If a person tests Positive for IgM, but not IgG antibodies, they are still at an active stage of the virus and can infect others. 

If a person tests Positive for both IgG and IgM antibodies, the infection has moved past the initial stage and into the second phase. If IgM antibodies show up on a test, that means a person could still be infectious and will need to limit their exposure to others. 

If a person tests Negative for both IgG and IgM antibodies, that means there are no coronavirus antibodies currently present in their system. If that person still believes they have the virus after testing negative, then a viral test is recommended for further evaluation.

An Invalid result indicates that there may have been a misstep in the testing process and the test will need to be re-administered. 

At the time of this post, it is still unknown exactly how much protection IgG antibodies provide against coronavirus re-infection. Antibody test results do not excuse anyone from following social distancing guidelines or the use of protective face coverings.


Antibody Tests Should Be Used When:

  • Your doctor or healthcare provider recommends you get tested
  • Someone close to you is confirmed to have COVID-19
  • You have been to a place where COVID-19 infection is common
  • You believe you were exposed to COVID-19 in the past but were not tested at the time 


The Importance of Antibody Testing

Not everyone who is infected with COVID-19 develops symptoms. Some individuals are asymptomatic and do not know they have contracted the virus. Antibody tests can give health officials a better idea of how common the virus is and how quickly it spreads. They can also study what happens when individuals who have developed the antibodies come into contact with the virus again. The hope is that once we better understand COVID-19 immunity, people who possess the antibodies may safely get back to their “normal” lives.

These tests can also aid in the development of convalescent plasma therapies against COVID-19. Many organizations, including ThermoGenesis, are currently studying how antibodies in plasma donated by individuals who’ve recovered from COVID-19 might help those who are struggling with infection. Along with the development of a vaccine, convalescent plasma therapies can be a major tool in helping curb the future spread COVID-19. 


How We Can Help

ThermoGenesis Holdings, Inc. (formerly Cesca Therapeutics Inc.), is a pioneer and market leader in the development and commercialization of automated cell processing technologies for the cell and gene therapy fields. We market a full suite of solutions for automated clinical biobanking, COVID-19 antibody testing, point-of-care applications and large scale cell processing and manufacturing with a special emphasis on the emerging CAR T immunotherapy market. We are committed to making the world a healthier place by creating innovative health solutions for everyone. 


If you’re a healthcare professional looking for more information on how to buy our COVID-19 IgG/IgM antibody testing kit, visit our website and request a quote today. 

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