- After participant enrollment, data on baseline characteristics, time since HIV diagnosis, CD4 counts, HIV viral load, antiretroviral treatment regimen and duration will be collected, then the participants will be randomized into 2 groups to receive either 3- or 4-standard doses (20 mcg per dose) of HBV vaccination, and follow-up blood test for anti-HBs titers at multiple pre-specified time points to evaluate outcomes