CD8A and syphilis: GEE analysis model revealed that elevated HLA-DR + CD8+/CD8 + % levels were associated with HIV/syphilis co-infection (OR = 1.026, 95% CI = 1.007–1.046; p = 0.007) and syphilis recurrence/reinfection/serofast state (OR = 1.036, 95% CI = 1.008–1.065; p = 0.012).