Old BMJ article from 2021

Data indicate that neutralising antibodies last for several months in patients with covid-19 but gently fall in number over time. One study, published in the journal Immunity, of 5882 people who had recovered from covid-19 infection, found that antibodies were still present in their blood five to seven months after illness. This was true for mild and severe cases, though people with severe disease ended up with more antibodies overall.

All of the vaccines approved so far produce strong antibody responses. The study group for the Moderna vaccine reported in April that participants in an ongoing clinical trial had high levels of antibodies six months after their second dose. A study in the Lancet found that the Oxford-AstraZeneca vaccine induced high antibodies with “minimal waning” for three months after a single dose.

Natural immunity appears slightly better than from the vaccines but there was some debate it may be more specific to the strain and give less broad based coverage.

It'll be interesting to see what they think currently.