Immune responses to SARS-CoV-2 might last for years, according to a study posted on the preprint server bioRxiv.
Some 185 adults who recovered from COVID-19 (most had mildly symptomatic disease) provided blood samples for analysis. The majority provided a single sample, but roughly 20% provided multiple samples over several months.
The researchers found that levels of spike-specific memory B cells (which make antibodies as needed) increased with time — and were higher at 4–6 months than at earlier time points in most participants who gave multiple samples. In addition, SARS-CoV-2 spike IgG titers were generally stable, showing only modest declines at 6–8 months.COVID-19: Study Suggests Durable Immune Response After SARS-CoV-2 Infection — https://www.jwatch.org/fw117245/2020/11/17/covid-19-study-suggests-durable-immune-response-after
I hope these findings are replicated in other studies.