75 subjects at risk for HIV infection (25 high risk MSM and 50 sero-discordant couples) will be recruited. All subjects will receive Truvada for pre-exposure prophylaxis or PrEP, as well as routine medical evaluations during one year. Subjects will be managed according to CDC's guidelines on the management of PrEP as a tool for HIV prevention.

75 subjects at risk for HIV infection (25 high risk MSM and 50 sero-discordant couples) will be recruited. All subjects will receive Truvada for PrEP, as well as routine medical evaluations during one year. Subjects will be managed according to CDC's guidelines on the management of PrEP as a tool for HIV prevention.

All subjects will have a total of at least 8 study visits during which routine assessment are performed for patients on Truvada for PrEP. Apart from offering routine medical care, a baseline questionnaire that includes socio-demographic variables, PrEP knowledge and acceptability and sexual conducts will be offered. At the 6 months visit, an abbreviated sexual conducts questionnaire will be offered.

Inclusion Criteria:

1. Subject is a male, female or transgender female age 21 or older

2. Subject provides written informed consent.

3. Subject provides written authorization for use and disclosure of protected health information (PHI).

4. Subject has one of the following risk factors:

   • male, female or transgender female or female sexual partner of an HIV-infected individual, ideally who is not virologically suppressed
   • high risk MSM as defined by: having unprotected sexual intercourse with at least two male partner in the last 6 months, or
   • diagnosed with an STI in the past 6 months

5. Baseline eCrCl of ≥60 ml/min (calculated using the CKD-EPI formula)

6. Negative Hepatitis B serology

7. No medical contraindications to the use of PrEP

8. Confirmed HIV negative by 5th generation (AB/antigen) HIV test

Exclusion Criteria:

1. younger than 21 years of age
2. unable to provide consent
3. Female who is pregnant, breast-feeding or intends to become pregnant or is of childbearing potential and not using adequate contraceptive methods (adequate contraceptive measures as required by local regulation or practice).
4. Positive pregnancy test: Women of childbearing potential must have a negative serum or urine pregnancy test within 1 week prior to study entry. Pregnancy testing will also be performed in enrolled female participants prior to any study procedures being performed
5. Baseline eCrCl <60 ml/min
6. Positive Hepatitis B serology to avoid potential flares upon product discontinuation
7. Any medical contraindication to the use of PrEP or any other conditions deemed by the study investigator to exclude the subject's participation in the study
8. HIV infected
9. Signs and symptoms of acute HIV infection
10. For sero-discordant couples: upon review of HIV positive partner's chart, evidence of resistance to any of the components of the study drug.
11. Illness or other condition that, in the opinion of the PI, may interfere with study participation at the time of enrollment.

Trans-gender female will be allowed in the study