Antibody test may not be ‘best’ gauge of protection vs COVID-19 — experts

FILE PHOTO: In this photo, Dr. Nita Patel, Director of Antibody Discovery and Vaccine development, lifts a vial with a potential coronavirus, COVID-19, vaccine at Novavax labs in Rockville, Maryland on March 20, 2020. (Photo by ANDREW CABALLERO-REYNOLDS / AFP)

MANILA, Philippines – Antibody tests may not be the “best” way to measure a person’s level of protection against the coronavirus disease (COVID-19), experts said Wednesday.

During the briefing of the House committee on health, Quezon Rep. Angelina Tan asked if neutralizing
antibody tests can serve as the basis of status of a person’s immunity against COVID-19.

Tan shared that she and her husband — both of whom have already been vaccinated against COVID-19—underwent antibody tests. However, their results varied, with her husband having “favorable” results for the antibodies, while she had a “negative” result.

However, Dr. Michelle De Vera of the Philippine Society for Allergy, Asthma, and Immunology said that antibody tests may not be the “best” measurement for one’s protection against COVID-19.

“Currently, I know that everyone’s testing for it and people are freaking out because they’re negative or low or ‘why is my kapitbahay [antibodies] higher than mine’. Certainly, it might not be the best test this time and it might actually make people worry and, you know, ‘should they get more boosters should they get another vaccine etcetera’. Currently, we have no data to support that,” De Vera said.

De Vera further said that “one measurement cannot totally measure the entire immune response of your immune system to the COVID virus.”

“In the studies that we’re going to conduct, as was mentioned earlier, the antibodies will be tested, but also other things like your cellular response, which is a little bit more technical in terms of looking at other parts of your immune system and see that response as well,” De Vera said.

“The second one, obviously, in the end, I guess the proof is in the pudding. And we’re also going to follow people over time to see if they actually contract the disease or not, because that will be the real test for whether you’re protected to this virus or not,” she added.

Meanwhile, Dr. Jaime Montoya, executive director of the DOST-Philippine Council for Health Research and Development, said that antibody tests is only one of the “surrogate markers.”

“Meaning, it is not yet the accepted marker that you are protected or immune,” Montoya said.

“It only the describes what we call the anti-body-based immunity. There is also what we call the cell based immunity, which is not actually covered by this test, and are covered by other cell based tests which are more complicated and sophisticated,” he added.

The US Food and Drug Administration (FDA) earlier reminded the public and health care providers that results from currently authorized COVID-19 antibody tests should not be used to evaluate a person’s level of immunity or protection from the disease at any time, and especially after the person received a COVID-19 vaccination.

The US FDA said that while a positive antibody test result can be used to help identify people who may have had a prior COVID-19 infection, more research is needed in people who have received vaccination.

EDV