In a study including > 1000 participants a significant waning of antibody levels was observed following vaccination.
The rate of antibody waning was not affected by pre-immunity or age.
Vaccination after infection induced about 200% of antibodies compared to non infected individuals.
https://www.mdpi.com/2076-393X/10/5/696
Infection not necessarily induces protecting antibodies to Sars-CoV-2
Within an award-winning study Dr. Pia Gattringer at the medical university of vienna found out that about 20% of persons recovered from an SARS-CoV-2 infection