This will be a prospective study that will enroll up to 600 older adolescent MSM and TGW from community-based clinics in Bangkok, Chonburi, Chiang Mai, and Songkhla.

All eligible participants will be followed up at month 3, 6, 9, and 12; month 6 and 12 will be mandatory clinic visits, while month 3 and 9 will be either clinic or a virtual visits. For participants accepting PrEP, additional follow-up visit at month 1, 2, 4, and 5 will be appointed; all visits will be either clinic or virtual visits.

Study Sites

The study will take place at the following community-based clinics:

1. SWING DIC, Bangkok, Thailand
2. RSAT DIC, Bangkok, Thailand
3. SWING DIC, Chonburi, Thailand
4. Sister DIC, Chonburi, Thailand
5. Caremat DIC, Chiang Mai, Thailand
6. MPlus DIC, Chiang Mai, Thailand
7. RSAT DIC, Songkhla, Thailand

Inclusion Criteria:

1. Thai nationality

2. Age 15-19 years old

3. Men or transgender women who have sex with men

4. HIV-negative at the time of screening

5. Have at least one of the following risks for HIV acquisition in the past 6 months:

   1. Any unprotected receptive anal sex with a male partner
   2. More than 5 male partners, regardless of condom use and serostatus
   3. Has had a bacterial sexually transmitted infection (STI)
   4. Any injected drug use

6. Calculated creatinine clearance (CrCl) ≥ 75 mL/min, as estimated by the Cockcroft- Gault equation

7. Alanine aminotransferase (ALT) ≤ 2.5 x ULN

8. Have signed the informed consent form

Exclusion Criteria:

1. HIV-positive
2. Hepatitis B infection as indicated by positive hepatitis B surface antigen (HBsAg) test at time of screening
3. Known allergy/sensitivity to tenofovir or emtricitabine

Approximately 600 older adolescent MSM and TGW