MANILA, Philippines — Getting antibody tests after getting a COVID-19 vaccine is not advisable, medical experts said, as they typically do not paint a full picture of immunity against the coronavirus and may even cause unnecessary worry over the effectiveness of the shot.
Doctor Michelle de Vera, who leads the government’s study on mixing vaccines, told the House health committee on Wednesday that antibody tests “might not be the best test at this time” to determine whether someone has developed immunity after getting vaccinated.
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“The immune system is amazingly sophisticated. So one measurement cannot totally measure the entire immune response of your immune system to the COVID virus,” de Vera said during the briefing to lawmakers.
She said that there are still no studies which suggest how many antibodies a person needs to be considered to be protected against COVID-19.
She added that while they will also use antibody tests in their study to check if people involved have developed an immune response, they will also be looking at the cellular response and will monitor study participants to check if they develop COVID-19.
Doctor Regina Berba, who is leading the government’s study on the effectiveness of COVID-19 vaccines in the real world, said they will also be employing the same methods in their study.
“We should not, on an individual basis, recommend to do antibody testing. Siguro (Maybe) only in the setting of trials right now para (so that) we see trends and mean averages of what exactly these numbers mean,” Berba said.
Not detected by antibody tests
Doctor Jaime Montoya, executive director of the Department of Science and Technology’s Council for Health Research and Development, said antibody tests are only accepted as “surrogate markers” for immunity, but these only cover antibody-based immunity and does not account for cell-based immunity.
“Alam naman po natin na ang proteksyon ng tao ay hindi lang sa antibodies. Kasama po diyan ‘yong cells na tinatawag. ‘Yong T-cells, ‘yong mga killer cells, yan po, na hindi po kasama sa mga antibody detections,” Montoya said.
(We know that people are not protected just because of antibodies. Cells are also included in this. T-Cells, killer cells are not detected by antibody tests.)
Berba also said that the antibody tests available in the market were designed to detect natural infections and not the body’s immune response to the vaccine.
It is not only local authorities that advice against antibody testing after vaccination.
The United States’ Food and Drug Administration, for one, has cautioned the public and healthcare providers that antibody tests should not be used to assess immunity as they have only been authorized to detect previous infections.
Local health authorities, however, have not yet issued an advisory on this, despite antibody tests being performed on people who have gotten their COVID-19 shots.
“If we can request the Department of Health and the other agencies here to give a categorical response regarding this because it’s not only an unnecessary expense on the part of the general public, it is also giving and sowing a lot of confusion,” said Rep. Janette Garin (Iloilo), who was former President Benigno Aquino III’s health secretary.