Additional Study Information: PrEP (Pre-Exposure Prophylaxis) is medication that is taken to help prevent HIV infection even if they are exposed to HIV. Research is continuing to find other, more convenient types of PrEP. This study is important because people in many areas of New York City have high rates of HIV acquisition, but use of prevention medication (PrEP) is low. The purpose of this study is to develop a new form of PrEP that can be given as a shot every 52 weeks. We will study how an investigational long-acting injectable HIV prevention medication, Lenacapavir (LEN for short) moves throughout the body, is tolerated, and whether the medication stays in the blood at levels that are high enough to prevent acquiring HIV for 52 weeks. In the first phase of this study (which lasts 52 weeks), you will receive two injections of LEN on day # 1 given intramuscular (into the muscle of the buttock) and will take 2 pills on day # 1 and again on day # 2. Other visit procedures include questionnaires about sexual behaviors, intimate partner violence, family planning, physical exams, and tests of blood and urine. You will have blood drawn for HIV testing and have testing for other sexually transmitted infections. There are 6 required visits in the first 52 weeks. You will be compensated for your time and travel at the end of each required study visit. After completing the first phase, you will be given the opportunity to transition to an optional Extension Phase, where you may continue to receive intramuscular LEN injections every 52 weeks until intramuscular LEN becomes available or until the sponsor elects to discontinue the study, whichever occurs first.