Additional Study Information: This research study is being conducted to see if HIV antiretroviral medicines that you are taking continue to work well in transgender women and other individuals identifying as female or transfeminine, but with male sex assigned at birth (referred to as transgender) when taken with feminizing hormone therapy (FHT), also known in this study as estradiol. You will receive estradiol as FHT. FHT is used by some transgender women as part of their gender-affirming care. This study will also assess if estradiol levels in blood vary between boosted and unboosted HIV medicines when transgender women are taking different doses of FHT. The study will enroll in total 90 participants: 30 in three different groups. Approximately 5 participants will enroll at Columbia University Irving Medical Center (CUIMC). The groups are based on what HIV medicines individuals are taking. The study will last for 48 weeks, or about 12 months. At all study visits, some blood will be collected from a vein in your arm, so you will need to arrive fasting. This means that you will not eat or drink anything other than water and your prescribed medications for at least 8 hours before the visit. You will also complete surveys, and you may participate in three 20-minute virtual interviews. You will be compensated for taking part in this study and receive a minimum of approximately $475 in total for the completion of all required study visits.