Immunogenicity and reactogenicity of yellow fever vaccine in people with HIV

OBJECTIVE: To evaluate immunogenicity and reactogenicity of yellow fever (YF) vaccine in people with HIV (PWH) compared to HIV-uninfected controls. DESIGN: In this longitudinal interventional trial (NCT03132311), PWH with CD4(+) cell count ≥200 cells/μl and controls, aged 18–59, without a previous history of YF vaccination received a single standard dose of YF vaccine (17DD) and were followed at Days 5, 30 and Year 1. METHODS: YF-neutralization titers were measured at Days 0, 30 and Year 1 and geometric mean titers (GMT) were calculated. Adverse events (AE) and YF virus detection were measured at Days 5 and 30. Linear regression evaluated factors associated with YF-neutralization titers. RESULTS: Two hundred and eighteen PWH and 82 controls were included. At baseline, all PWH were using antiretroviral therapy; 92.6% had undetectable HIV viral load (VL) and median CD4(+) cell count was 630 cells/μl [interquartile range (IQR) 463–888]. YF vaccine was safe and there were no serious AEs. At Day 30, seroconversion was observed in 98.6% of PWH [95% confidence interval (CI): 95.6–99.6] and in 100% of controls (95% CI: 93.9–100); at Year 1, 94.0% of PWH (95% CI: 89.6–96.7) and 98.4% of controls (95% CI 90.3–99.9) were seropositive. PWH had lower GMTs than controls at Day 30 and Year 1. Baseline VL >1000 copies/ml, low CD4(+) cell count and low CD4(+)/CD8(+) ratio were associated with lower YF-neutralization titers. CONCLUSIONS: YF vaccine is safe in PWH with CD4(+) cell count ≥200 cells/μl. YF vaccine immunogenicity is impaired in PWH, particularly among those with high VL, low CD4(+) cell count and low CD4(+)/CD8(+) ratio at vaccination and YF-neutralization titers decays over time.