July 25 (UPI) -- New research has shown that use of a monthly vaginal ring and a daily oral Truvada are safe and effective at preventing HIV in adolescent girls.
The experimental vaginal ring is designed for HIV prevention, while the oral tablet has already been approved for HIV prevention in adults.
"Adolescents and young people represent a growing share of people living with HIV worldwide," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, said in a press release. "Science has demonstrated that the HIV prevention needs of adolescents may be different than those of adults, which is why these new study findings are so important."
The study was the first time the vaginal ring was tested in girls younger than 18 and the first clinical trial of oral Truvada as pre-exposure prophylaxis, or PrEP, for adolescents. Truvada contains the HIV prevention drugs tenofovir and emtricitabine.
The study, called Choices for Adolescent Prevention Methods for South Africa, or CHAMPS PlusPills, involved 148 healthy, sexually active South African adolescents -- 99 girls and 49 boys -- between age 15 and 19 in Cape Town and Johannesburg.
Most participants chose to take Truvada, however, the number of participants who took the drug as prescribed was lower than the number who opted in and then decreased use over time.
Researchers found that tenofivir was detectable in the blood samples of 57 percent of participants at the three-month mark, and 82 percent of participants continued to take Truvada for PrEP. At six months, tenofovir was detectable in the blood samples of 38 percent of participants, and 64 percent of participants opted to continue or resume taking the drug.
"The trend toward lower adherence to Truvada for PrEP as study visits became less frequent parallels what was observed in in a study of PrEP in adolescent gay and bisexual boys, suggesting that monthly study visits may support greater adherence to oral PrEP among adolescents over time," said Linda-Gail Bekker, deputy director of the Desmond Tutu HIV Center at the University of Cape Town.
Previous studies showed women age 18 to 45 using a vaginal ring that continuously releases the experimental HIV-prevention drug dapivirine showed 27 percent protection overall but not in women age 18 to 21 due to low adherence.
The new Phase 2a clinical trial known as MTN0023/IPM 030 examined the safety and efficacy of the dapivirine ring in girls age 15 to 17.
Results showed the ring was safe to use and adherence was high, with 87 percent of the drug levels found in blood samples and 95 percent of rings used met adherence criteria.
"We are encouraged by these results of the dapivirine ring in 15- to 17-year-old girls," Sharon Hillier, principal investigator of the NIH-funded Microbicide Trials Network, said.
"The study has demonstrated that the ring is safe in U.S. teens, and now we need data on the safety and acceptability of the ring in African adolescent girls. The REACH study, scheduled to launch later this year, will generate this data."