Follow up Sars Cov 2 Antibodies

I received second dose of Comirnaty (BNT162b2) Pfizer BioNTech vaccine on Jan 18
After 14 days I was monitored for antibodies, result:
>800 AU/ml (Positive >= 13 AU/ml)
I was monitored for second on April 28, result:
107 AU/ml (Positive >= 13 AU/ml)
The next monitoring will be made 6 months after second dose.
A decline is still expected but much less important.