New COVID-19 Antibody Test 'Glows' When Antibodies Are Present

Researchers have developed a new test that can measure a person’s level of COVID-19 antibodies with just a prick of blood, and deliver the results within one hour.

While it’s not on the market yet, the test has the potential to help us understand how long protection against the COVID-19 virus lasts after infection or vaccination. 

Scientists at the University of Toronto created the test, which determines the number of antibodies in a blood sample using a light-emitting enzyme that gives off a flash of light when antibodies are present.

The test is not yet available for commercial use, but its creators recently published their findings in the journal Nature Communications and are in talks with partners about how to bring the test to healthcare settings.

Igor Stagljar, PhD, a professor of biochemistry and molecular genetics at the University of Toronto, and his lab developed the test. Stagljar tells Verywell that with mass COVID-19 vaccinations, “it will be very important to follow the amount of immunity that a certain person has after they get vaccinated.”

Stagljar adds that “it’s also very important to follow the duration of immunity in people who already got infected with this virus.” His hope is that the test his lab developed can be another tool.

“By having such a simple but precise, accurate, and cheap tool in our hands, I think we will be able to assess the immunity of these people in a very convenient way,” Stagljar says.

How the Test Works

The test, called SATiN (which stands for Serological Assay based on split Tripart Nanoluciferase), uses an enzyme called luciferase (the same enzyme that makes fireflies glow). 

While luciferase is widely used in biotechnology, Stagljar and his lab use a method developed by Shawn Owen, PhD, an assistant professor of biological chemistry at the University of Utah and a collaborator on the test. The new method, which splits the luciferase into three parts, is what makes the test unique.

What the Test Does

First, the researchers took the three luciferase parts and attached one piece to the coronavirus spike protein—the section of SARS-CoV-2 that antibodies bind to in order to neutralize the virus. Next, they took the second piece and attached it to a protein that recognizes antibodies in the blood sample. As for the third piece of luciferase, Stagljar explains that it is not fused to anything.

“We basically incubate those three little molecular biological pieces with a prick of blood,” Stagljar says. “And if there are antibodies against SARS-CoV-2 in the blood, these antibodies will ‘glue’ the three parts of luciferase into a functional molecule that will start shining.”

In other words, you need to have COVID-19 antibodies present to make the enzyme glow. When the glow occurs, the researchers can then measure the amount of light emitted with an instrument called a luminometer. The more antibodies a person has, the brighter the luciferase will shine.

“We not only can say does somebody have an antibody, but also what is the level of that antibody,” Owen tells Verywell. “And that’s really significantly different than most of the antibody assays out there.”

Why Antibody Tests Are Important  

Antibody tests can determine how much protection a person who was previously infected with COVID-19 has once they have recovered—information that will be key to dealing with concerns about COVID-19 reinfection.

Additionally, as COVID-19 vaccines roll out across the world, antibody testing can be an important tool for monitoring how well the shots create an immune response. 

“After vaccination, we can take a little bit of blood from people and test how high the antibody level is,” Zhong Yao, PhD, a senior research associate in Stagljar’s lab and the test’s co-inventor, tells Verywell. 

Owen says that the test could also help monitor how long antibody protection might last—either after someone has recovered from COVID-19 or after they receive a COVID-19 vaccination. 

“If we see the antibody levels start to drop off, then that might be an indication that protection might be waning a little bit,” Owen says—insights that could be especially relevant for drugmakers working on COVID-19 vaccine boosters. 

The Future of SATiN 

The test’s developers are currently trying to bring their product to market with a commercial partner. It only costs about $2 CAD to process each blood sample, and the test results show in less than an hour—attributes that the researchers believe will make the test useful in point-of-care settings. 

While working to make SATiN widely available, the researchers are already thinking about what’s next as the COVID pandemic evolves and variants of concern continue to cause new infections. 

For the test’s next iteration, Owen says that the researchers want to focus on differentiating variants in blood samples. They’re hoping to find out whether the antibodies a person currently has will protect them against new variants, and whether someone who has been vaccinated will be protected against variants.

Owen also says that it’s important to note that even if you have some antibodies, it does not mean you are in the clear or should not get vaccinated against COVID-19. Antibody tests are just one tool in helping combat the pandemic.

“Just because somebody has antibodies now doesn’t mean they’re going to have antibodies later,” Owen says. “And it doesn’t mean that they’re going to be protected against variants.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.