Additional Study Information: HPTN 102/ PURPOSE 3 is a clinical study being done with cisgender women in the US to see whether an investigational twice-a-year (every 6 months) injection medicine can help reduce the risk of getting HIV from sex. The safety and efficacy of the medicine, which is called lenacapavir (LEN), is being studied for the prevention of HIV as pre-exposure prophylaxis, or PrEP. The study will also include Truvada (F/TDF), a medicine approved in the US as PrEP for HIV prevention. This study is supported by, and in partnership, with the HIV Prevention Trials Network (HPTN) and is one of the many trials working to expand global HIV prevention efforts. The study will last approximately 2 years. In the first year, participants will be randomly assigned in a 1:1 ratio to take either LEN injections (given at study enrollment and again at 6 months after enrollment) or Truvada (F/TDF) tablets to be taken every day. After the first year, everyone in the study will get F/TDF tablets to take every day for up to an additional 1 years. Study participation over the 2 years of the study entails approximately 6-8 in-person study visits per year, which include blood draws and urine tests to test for HIV and sexually transmitted infections, physical examination, and questionnaires. We will also assess and record all side effects that participants experience during the study. In other studies, the most common side effects of LEN were reactions at the site of the injection.