A 43-year-old man with HIV and hepatitis B virus (HBV) coinfection is starting on antiretroviral therapy with bictegravir-tenofovir alafenamide-emtricitabine. Baseline laboratory studies show a CD4 count of 424 cells/mm³, HIV RNA 123,344 copies/mL, positive hepatitis B surface antigen (HBsAg), positive hepatitis B e antigen (HBeAg), and HBV DNA level of 1,980,000 IU/mL. The follow-up HBV DNA level 12 weeks after starting therapy is 34,650 copies/mL and 24 weeks after starting therapy it is 1,880 copies/mL. The HIV RNA level was below the limit of detection at week 12.