This COVID-19 antibody test can predict if you'll have severe disease

Posted at 11:20 AM, May 27, 2021

IRVINE, Calif. — Researchers at the University of California Irvine have developed a new kind of COVID-19 antibody test that can predict early on if someone will have a severe case of the disease.

The two-step test works by searching a patient’s blood for what the scientists call “bad antibodies” that are produced early in the infection. Then, they grade the patient for risk factors like age, sex and pre-existing conditions.

When the bad antibodies are present in a patient with three or more risk factors, the test can predict if a person is on track for hospitalization or worse with 96.7 percent accuracy, according to the study published in mSphere.

A simple blood test available in labs around the world can reveal the bad antibodies within the first few days of the disease, potentially as early as one day after symptoms appear, according to UC Irvine professor Gregory Weiss, who oversaw the research.

The test could help doctors quickly identify patients for targeted treatments, Sanjana Sen, a UC Irvine graduate student, said. Sen led the study alongside fellow PhD candidates Emily Sanders and Kristin Gabriel.

“What we really wanted to have is something that we could see a patient, diagnose them almost immediately, and have them triaged in a certain way,” Sen said.

Early on in the pandemic, Weiss tasked his students with trying to develop a conventional antibody test for COVID-19 when Sen got an idea. Why not try to develop a test that doesn’t just identify the virus, but helps predict who will have a poor outcome?

The team set about looking for patterns in the records of 86 patients, and they found a sizable share of the people who got really sick had one particular antibody: an antibody that attaches to a part of the virus called epitope 9.

Antibodies are the virus-fighting molecules much discussed in the context of vaccines. Good antibodies bind to the spiky protrusions on the surface of the coronavirus, known as the spike protein.

“A spike antibody physically blocks the coronavirus from getting into your cells,” Sanders said.

Occasionally, when a patient has a lot of infection, a virus particle can break apart, exposing features on the inside of its shell. Some people start making antibodies shaped to those inner features.

The end result, explained Gabriel, is that their immune system spends a lot of time and energy making antibodies that are essentially useless.

“It's sort of like your immune system is at the wheel of a car and it takes a bad, wrong turn early on in the course of the disease,” Weiss said. “It’s very hard to come back from after it has done that.”

The presence of the bad antibodies alone, without the risk factor score, can foreshadow severe disease with 83.6 percent accuracy, according to the study.

But when risk factors are taken into account, the test becomes even more sensitive. Those risk factors include being over 50 years old and conditions like high blood pressure, obesity, diabetes, kidney disease, lung disease, cerebrovascular disease, and cancer. Men are also at greater risk than women.

People who have three or more of these risk factors — such as men over 50 who have high blood pressure — have a nearly 14 times greater likelihood of severe disease if the bad antibody is detected, the researchers found.

The researchers stress that testing negative for the antibodies isn’t a clean bill of health. Only about one-quarter of the patients who developed severe disease in the study had the bad antibodies, a sign that a person’s health can deteriorate for many reasons unrelated to this immune phenomenon.

But among the subset of people with this bad antibody, the researchers hope this predictive test can help people get better treatment sooner. And the best part?

“It can be picked up anywhere where people are doing a conventional blood test for virus antibodies,” Gabriel said.

Labs around the world already have the equipment they need to replicate this test. The UC Irvine team decided not to patent the technology, so anyone can start testing for these bad antibodies today.

“There's nothing more important that we scientists can do than to get technologies that are inexpensive out into the field where they can make a difference in people's lives,” Weiss saod.

And it might. Weiss said he’s already had discussions about the test with the World Health Organization.

This story was originally published by Derek Staahl on Scripps station KGTV in San Diego.