Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend only daily Truvada for use as PrEP. Data on efficacy and safety of PrEP in adolescents are insufficient. Risks and benefits of PrEP use should be considered for adolescents. Possibility of increased risk-taking While PrEP appears to be extremely successful in reducing HIV infection , there is mixed evidence that there might be a change in use of condoms in anal sex, raising risks of spreading sexually transmitted infections other than HIV. In a meta-analysis of 18 studies, researchers found that rates of new diagnoses of STIs among MSM (men who have sex with men) given PrEP were 25.3 times greater for gonorrhea, 11.2 times greater for chlamydia and 44.6 times greater for syphilis, compared with the rates among MSM not given PrEP. Unlike HIV, these three STIs can be cured with antibiotics. However, the increased rates of such infections and their treatment can lead to antibiotic-resistant mutations of the pathogens; antibiotic-resistant gonorrhea is already a major concern. A systematic review conducted in 2019 was unable to find conclusive evidence that PrEP use increases sexual risk behaviors, and found that PrEP may provide an opportunity for MSM to access sexual health care, testing, treatment and counselling services. Emerging treatments Although HIV PrEP medications are only available in oral tablet and injectable formulations, other formulations are being developed and studied. The emerging treatments expand HIV prevention strategies for women. For example, a vaginal gel formulation of tenofovir and an intravaginal ring releasing dapivirine are under investigation for efficacy. Out of three completed trials evaluating safety and efficacy of tenofovir vaginal gel, only the CAPRISA 004 trial showed the drug to be efficacious in decreasing the risk of HIV infection. However, the demonstrated effectiveness of tenofovir vaginal gel was deemed not significant enough to move forward with the product. In contrast, the ASPIRE study and The Ring Study evaluating the dapivirine-releasing intravaginal ring have demonstrated efficacy in reducing incidence of HIV infection. In addition to these two treatments, an injectable form of cabotegravir is being evaluated for efficacy in the HPTN 03 and HPTN 04 trials. See also Chemoprevention Post-exposure prophylaxis (PEP) National AIDS Trust v NHS Service Commissioning Board References External links PrEPWatch PrEP Watch homepage CDC Pre-Exposure Prophylaxis (PrEP), Centers for Disease Control and Prevention (CDC) CM Mediclinic Thailand What is PrEP? The Game Changer Project