@janbb Your friend needs to make sure they had the right type of antibody test. Here’s an article. I have been wondering about the antibody question also, because of the Pfizer study where so many elderly people didn’t produce antibodies. I assume a study used the correct test though. I still don’t really understand if maybe someone can not show the antibodies and still be immune. Maybe the body will still recognize the virus and react.
I heard the CDC director today say that immunocompromised people also may not get a good immune response from the vaccine, I don’t think they know yet the full information on that. She said those people should talk to their doctor, which I think is a crap answer, because a doctor would not likely know more than her, unless maybe he would actually run an antibody test. I figure doctors are going to tell their chemo patients and people on immunosuppressants to still take precautions, but I’m not a doctor. I mean, those people need to be cautious even without covid around. The CDC director did not say anything about a third shot.
I have no idea if this will apply to covid vaccine, but my mother never reacted to the smallpox vaccine, so they made her do it again. A few years later she was going to travel and they advised she get the vaccine again since she never reacted, and she refused it, because she had no reason to believe it would leave a mark on the third try. I tell that story, because I think it is possible in the future they might advise another booster for people high risk showing no immunity.
I assume they have not done any trials for third doses, so they might be loathe to recommend it at this point.