A few quotes of hope if you score poorly on antibody tests. Documents links attached. Less likely to be relevant to the immunity-suppressed (like my wife) but some useful information here for others.

people with low levels of antibodies do still appear to be sufficiently protected, particularly against severe disease

Theconversation.com

There is wider immunity response:

Neutralising antibodies are an antibody that is responsible for defending cells from pathogens

[not to be confused with binding antibodies] …binding to a pathogen and alerting the immune system to its presence so white blood cells can be sent to destroy it.

News-medical.net

B-cells and T-cells…the adaptive immune system is slow and can take several days before two key cell types – B cells and T cells – are brought into play.

Once the adaptive immune system has vanquished the invader, a pool of long-lived memory T and B cells are made. These memory lymphocytes remain dormant until the next time they encounter the same pathogen. This time, though, they produce a much faster and stronger immune reaction.

Theconversation.com

We can hope that people with low levels of neutralising antibodies, even after a booster, will therefore be protected by these other immune defences remaining largely undiminished. This, though, is not a given, and we need further studies to measure real-life protection.

Theconversation.com

The article concludes, “levels of infection and disease attributable to omicron to allow rapid, rational public health decisions to be made. Research groups around the world are addressing all these areas and, in the near future, we can expect their reports to make the situation clearer.”