EVANSTON, IL — Is it possible you were infected with a mild form of COVID-19 and didn’t know it? How robust is your body’s immune response to the vaccine, and how will we know whether we’ve reached herd immunity? A new home antibody test could unlock the answers to those questions using a drop of blood.
With a single finger prick, scientists are hoping to measure coronavirus immunity levels across the population.
“There are a lot of people right now, because of limited vaccine supply, who don't know the level of immunity that they have,” explained biological anthropologist Thom McDade.
McDade and a team of scientists at Northwestern University developed the home antibody test that doesn’t require a hospital or clinic visit.
“One of the innovations of this approach is that allows people to collect samples from themselves in the comfort and privacy and safety of their home,” he said.
This test doesn’t tell you if you have COVID-19 when you take it. Instead, it focuses on neutralizing antibodies, which can actually measure how robust of an immune response you actually have following an infection.
“If you've been exposed previously, but might have had a mild or asymptomatic case, how much immunity do you carry forward and how much protection you have against subsequent re-infection from another exposure?”
The test itself is simple. A few drops of blood are added to a commonly used filter paper then sealed in a plastic bag and mailed off to the lab. There, the sample is mixed with a buffer agent that replicates infection and measures neutralization of the virus with a score of 1 to 100.
“If you have 100 percent neutralization that means high levels of neutralizing antibodies that are blocking that interaction between the virus and your receptors,” said McDade.
The investigators are already using the test in a 10,000-person study. That could help them understand community spread and how much protective immunity has developed.
“That could be people who have never exposed people who are exposed and asymptomatic and we can also use it to test the effectiveness of vaccines,” said McDade. “There might be people who have immunocompromised condition or who are older who might not generate as robust an immune response following vaccination and that would be useful information.”
With nothing proprietary about the process, following peer review, McDade said it could be made widely available with existing infrastructure and supplies and could help measure herd immunity.
It’s still not clear whether this test can measure the effectiveness of neutralizing antibodies against emerging variants, but researchers say it could be modified for specific variants as needed.