Below are quotes from the article Am I Immune to COVID-19 if I Have Antibodies? The items in bold are the main points to note which make it clear that the right kind of antibodies do provide immunity and the antibody test you take must be specific for that kind of antibody! Be clear that if this wasn’t the case there would be no point in developing a vaccine to protect the world against this virus!
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“The very best antibodies are ones that neutralize the receptor binding domain [RBD] of the new coronavirus spike protein that attaches to the host cell’s ACE2 receptor. The RBD is on the tip of the spike protein and is the part of the spike that touches ACE2. Antibodies against RBD block the very first step of viral infection, which is when the coronavirus attaches the human cell membrane.“
“Complicating things further is the fact that not all of the antibody tests for COVID-19 measure antibodies against RBD. Some tests measure antibodies against parts of the virus that are not needed for cell entry. These antibodies that are not against the RBD will recognize the virus but will not block it from infecting human cells and triggering viral infection.”
“So only antibodies that block the spike protein from connecting to the ACE2 receptor are guaranteed to provide immunity. And only antibody tests that measure the amount of these antibodies can predict immunity.“
