A pilot program of HIV pre-exposure prophylaxis in Thai youth

PLoS One. 2024 Feb 22;19(2):e0298914. doi: 10.1371/journal.pone.0298914. eCollection 2024.


Introduction: There are gaps in knowledge and experience of antiretroviral pre-exposure prophylaxis (PrEP) delivery in adolescents.

Methods: This pilot study enrolled Thai adolescents 14-20 year-old without HIV who reported risk behaviour. All participants were offered daily tenofovir/emtricitabine (TDF-FTC) and followed for 24 weeks. HIV testing, renal function, bone density scan, and sexually transmitted infection (STI) testing including syphilis serology and urine molecular testing for gonorrhoea and C. trachomatis were performed at baseline and weeks 12 and 24. Adherence was evaluated through intracellular tenofovir diphosphate (TFV-DP) levels in dried blood spots.

Results: Of the 61 enrolled adolescents, median age 18.1 (IQR: 14.8-20.9) years, 46 (75.4%) were males and 36 (59%) were MSM. Retention to week 24 was 80.3%. One third (36%) had TFV-DP levels consistent with taking ≥6 pills/week at week 12 and 29% at week 24. The factors associated with taking ≥6 pills/week were being MSM (adjusted odds ratio [aOR]: 53.2, 95% CI: 1.6-1811; p = 0.027), presence of STI at baseline (aOR: 9.4, 95% CI: 1.5-58.5; p = 0.016), and self-report of decreased condom use while taking PrEP (aOR: 8.7, 95% CI: 1.4-56.6; p = 0.023). 31% had an STI at baseline and this declined to 18% at week 24. No renal or bone toxicity was observed and there were no HIV seroconversions.

Conclusions: Daily oral PrEP with FTC-TDF in high-risk Thai adolescents is feasible, accepted, well-tolerated, and had no increased risk compensation; however, low adherence was a major challenge. Adolescent-specific PrEP strategies including long-acting modalities are needed for successful HIV prevention.

MeSH terms

  • Adenine / analogs & derivatives*
  • Adolescent
  • Adult
  • Anti-HIV Agents*
  • Emtricitabine / therapeutic use
  • Female
  • HIV Infections* / drug therapy
  • HIV Infections* / prevention & control
  • Homosexuality, Male
  • Humans
  • Male
  • Organophosphates*
  • Pilot Projects
  • Pre-Exposure Prophylaxis*
  • Sexual and Gender Minorities*
  • Thailand / epidemiology
  • Young Adult


  • Anti-HIV Agents
  • Emtricitabine
  • tenofovir diphosphate
  • Adenine
  • Organophosphates

Grants and funding

This study was funded by UNICEF, Bangkok, Thailand. The reach and testing activities of this work was supported by the Presidents’ Emergency Plan for AIDS Relief (PEPFAR) through the U.S. Centres for Disease Control and Prevention under the terms of NU2GGH001923-04. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.