Even if you don't have detectable levels of antibodies - if you've been previously infected or vaccinated - you will likely have robust and durable immunity that greatly reduces the risk of hospitalization and death [1][2][3].

[1] SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans https://www.nature.com/articles/s41586-021-03647-4.pdf

[2] Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells https://www.cell.com/cell-reports-medicine/fulltext/S2666-37...

[3] Rapid induction of antigen-specific CD4+ T cells is associated with coordinated humoral and cellular immune responses to SARS-CoV-2 mRNA vaccination https://www.cell.com/immunity/fulltext/S1074-7613(21)00308-3