I've had 2 Pfizer doses and was wondering if it's worth it to do a commercial antibody test to assess if I've had an adequate immune response and check antibody levels. This can also be used to decide whether to go for a 3rd booster shot if/when these become available.
Has anyone done this and do you think it would be useful?
It depends on the antibody test - some will not register anything for vaccinated people, others will register the vaccine reaction (I'm not sure which is which.) Either way, these results are not comparable to the reaction you have from getting COVID-19, so any comparison you make is ad-hoc, and you're not going to be able to infer how good or bad your post-vaccine immunity is this way, especially with sample size n=1.
My mother is immunocompromised, so we’ve discussed this with 4 doctors who specialize in assessing immuno-affecting conditions.
3/4 felt that the information gain from doing this would be negligible. 2 of those 3 have generally had strong epistemics during her treatment. The fourth (who has generally been least impressive, but sounded like she maybe had a good idea on this?), thought it may be mildly useful.
I'm a bit surprised by this. The entire logic behind booster doses for the immunocompromised (which several countries are already doing, e.g. US/UK) is based on a lack of (or low) immune response to the vaccine, which can be confirmed by an antibody test (measuring antibodies to the spike protein). There are studies with large numbers of people where you can see the median levels of antibodies in healthy adults and compare results (e.g. here and here). These tests are quantitative and give you a number, not just a positive or negative result, some people c... (read more)