Higher morbidity and mortality rates from pandemic COVID-19 are disproportionately observed in high-risk groups, including Indigenous people globally. We evaluated immune responses in Australian First Nations people and non-Indigenous individuals after COVID-19 BNT162b2 vaccination, and in First Nations people hospitalized with COVID-19. Our study provides evidence that First Nations people elicit effective immune responses following BNT162b2 vaccination: neutralizing antibodies, anti-RBD-antibodies, SARS-CoV-2 Spike-specific B cells, CD4+ and CD8+ T cells measured by activation-induced marker (AIM) assay, IFN‑γ/TNF production and peptide-HLA tetramer staining directly ex vivo. In First Nations participants, RBD IgG antibody titres positively correlated with the body mass index, while negatively correlated with age. Importantly, however, reduced SARS-CoV-2 antibody axis (RBD-antibodies, spike-specific B cells, T follicular helper (Tfh) cells) was found in vaccinated First Nations participants with chronic conditions (diabetes, renal disease). This was strongly associated with altered IgG glycosylation and increased IL-18 levels. First Nations people hospitalized with COVID-19 elicited broad immunity, including RBD/nucleoprotein-antibodies, antibody-secreting cells, Tfh cells, tetramer-specific CD4+/CD8+ T cells with prominent TCR motifs and peptide-stimulated AIM+ T cell frequencies. Our study provides key insights into immune responses following SARS-CoV-2 infection and vaccination in Indigenous people, links for the first-time antibody glycosylation levels to reduced antibody titres post COVID vaccination and emphasizes the importance of vaccine-induced T cells in individuals with co-morbidities.