Can antibody tests determine if the COVID-19 vaccine was effective?
The Centers for Disease Control and Prevention (CDC) discourages antibody testing for assessing immunity after getting the vaccine.
A vaccinated person is very likely to get a negative result from a serology test, even if the vaccine was successful and protective. That’s because different serology tests detect antibodies to different parts of the virus.
Some tests detect antibodies to the spike protein of the virus, which are produced in response to viral infection or the vaccine. Others detect antibodies to a different part of the virus called the nucleocapsid protein, which are produced in response to infection, but not by the current vaccines.
MD Anderson’s Blood Bank uses an antibody test designed to detect antibodies to the nucleocapsid protein, which means donors who have received the COVID-19 vaccine will likely receive a negative antibody test result.
“A vaccinated person should not be alarmed or worried if they receive a negative antibody test result because this test does not detect antibodies from the Pfizer, Moderna and Johnson & Johnson’s Janssen COVID-19 vaccines, which were developed against the spike protein of the virus,” says Fernando Martinez, M.D., medical director of Laboratory Medicine. “This reinforces the guidance from the CDC that serology tests should not be used to test for immunity.”
