There are limited data on varicella vaccination in HIV-infected adolescents or adults, although one study has reported on the safety and modest immunogenicity of two doses of varicella vaccine in HIV-infected adults with a CD4+ count above 400 cells/μL with a suppressed viral load.73 At present in Africa, there is a lack of varicella epidemiology and socio-economic data on the impact of this disease. The gene discussed is CD4; the disease is chickenpox.