Understanding why antibody tests can’t ‘check up’ on COVID-19 vaccine effectiveness

Dana Cohen shares experience

DETROIT – After you receive the COVID vaccine are you able to check up on it and make sure it’s working? It’s not as simple as getting an antibody test.

A Metro Detroit healthcare worker tried by getting her antibodies tested. Dana Cohen had her second vaccine on Jan. 11. She said she didn’t have any side effects beyond a sore arm.

READ: What are antibodies? Why is developing antibody testing for COVID-19 so complicated?

“I felt kind of funny that I didn’t have any kind of side effect from the second vaccine because it seemed like most people I talked to did have a reaction,” Cohen said.

Cohen said she began to worry that her body hadn’t responded to the vaccine. So she decided to get an antibody test.

“A couple of days later I got a negative result and I initially sort of freaked out,” Cohen said.

She sent her results to a colleague who noticed a key detail in the fine print. The test she took does not measure vaccine effectiveness.

While it seems logical that an antibody test would detect antibodies triggered by the vaccine, it is more complicated than that.

Many of the antibody tests don’t measure the antibodies you get from the vaccine. The vaccines only give you antibodies to the spike protein. If the test is looking for different antibodies it will be negative even if you have spike antibodies. It’s also important to note that the antibody tests aren’t perfect, there can still be false negatives and false positives.

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