The link is broken. There is a missing "o". https://www.businessinsider.com/omicron-resist-pfizer-vaccin...
IIUC it's not that the variant reduce the number of antibodies that you have. It is just that most of your antibodies are not effective against omicron.
> A team of researchers led by Africa Health Research Institute's Alex Sigal tested 14 blood samples from 12 people against a live sample of the Omicron variant. All 12 people were vaccinated, and six were previously infected.
> another group of researchers ... found a seven-fold reduction across 17 blood samples.
12 and 17 look like very small numbers, and the results are too different.