The total study duration is up to 15 years of follow-up post BIVV003 and/or ST-400 infusion.
Primary Objectives:~Long-term safety of BIVV003 in participants with severe sickle cell disease (SCD) and ST- 400 in participants with transfusion-dependent beta-thalassemia (TDT)~Secondary Objectives:~Long-term efficacy of the biological treatment effect of BIVV003 in SCD~Long-term efficacy of the clinical treatment effect of BIVV003 on SCD-related clinical events~Long-term efficacy of the biological treatment effect of ST-400 in TDT~Long-term efficacy of the clinical treatment effect of ST-400 in TDT