Long-term immune response to yellow fever vaccination in HIV-infected individuals depends on HIV-RNA suppression status: Implications for vaccination schedule. Clinical Infectious Diseases
Veit et al. studied the immune response over time to yellow fever vaccination (YFV) and the necessity for booster vaccination in 247 HIV-infected individuals from the Swiss HIV Cohort Study. A plaque reduction neutralization titer (PRNT) of 1:≥10 was regarded as reactive and protective.
At vaccination, 82% of the vaccinees were taking combination antiretroviral therapy (cART), 83% had suppressed HIV RNA levels (<400 copies/mL), and their median CD4 T-cell count was 536 cells/μL. PRNT was reactive in 46% before, 95% (95% CI, 91%–98%) within 1 year, 86% at 5 years, and 75% at 10 years postvaccination. In those with suppressed plasma HIV RNA at YFV, the proportion with reactive PRNTs remained high: 99% within 1 year, 99 at 5 years, and 100% at 10 years.
In conclusion, the study-results suggest that long-term immune response up to 10 years to YFV is primarily dependent on the control of HIV replication at the time of vaccination. Vaccinees on successful cART had high levels of reactive PRNT, and protective titers were maintained up to 10 years. The results point toward acceptable safety of YFV in HIV-infected individuals on cART. Until further data on long-term immunity are available, the authors recommend that HIV-infected patients should be vaccinated against YF once their HIV RNA is suppressed and receive a YFV booster after 10 years if they stay on uninterrupted successful cART to restimulate the vaccine response. However, HIV-infected persons who were vaccinated with replicating HIV should either have their PRNT measured or receive a booster YFV while on successful cART, irrespective of time elapsed since primary YFV.