Associate Scientific Director
Principal Investigator, CAPRISA Clinical Trials Unit
Durban, South Africa
Professor in Clinical Epidemiology
New York, New York
Honorary Professor in Public Health
University of KwaZulu-Natal
Durban, South Africa
Quarraisha Abdool Karim, PhD, has disclosed that she has intellectual property rights/patents from Gilead Sciences.
Of the nearly 6000 new HIV infections that occur each day worldwide, approximately 20% occur in adolescent girls and young women between the ages of 15-24 years. In sub-Saharan Africa, 56% of new HIV infections occur in women, and young women are twice as likely to become infected compared with their male peers. Women, especially adolescent girls and young women who are unable to negotiate safer sex practices with their male partners, therefore require HIV prevention options that they can initiate.
Microbicides and Oral PrEP
In 1990, a commentary by Dr. Zena Stein in the American Journal of Public Health highlighted the need for women-initiated prevention methods and catalyzed the search for a microbicide. Early microbicidal products evaluated in the 1990s and early 2000s were not HIV specific and were either nonefficacious or caused harm. The newer generation of prevention products are antiretroviral based and are also referred to as pre-exposure prophylaxis (PrEP). The CAPRISA 004 study demonstrated for the first time in 2010 that tenofovir gel reduced HIV infection rates by up to 54% in women who used the gel consistently. Further, tenofovir gel was shown to prevent HSV-2 infection of women by 51%. These data signaled new hope in the HIV prevention field on the role of PrEP and specifically for women-initiated technologies. Unfortunately, the VOICE and FACTS 001 trials were unable to confirm these findings due to adherence challenges. By contrast, trials of daily oral PrEP have demonstrated protective benefits in men and women who are not HIV infected. As a result, in September 2015, the World Health Organization released guidelines for the provision of daily oral tenofovir-containing tablets as part of combination prevention for all populations at high risk of acquiring HIV infection. Oral PrEP must be used consistently to offer protection against HIV, although there appears to be a higher threshold of drug levels needed by women compared with men. For example, men taking 4 of 7 tablets per week experience levels of protection similar to daily dosing. The drug is less forgiving in women as evidenced by results demonstrating that women who took fewer than 6 of 7 tablets per week received inadequate protection from infection.
Dapivirine Vaginal Ring
Research on women-initiated technologies is ongoing and includes evaluation of new, more potent drugs and slow-release and longer-acting formulations such as 2-3 monthly injections and longer-acting implants that are less user dependent. Data from the ASPIRE and IPM 027 RING efficacy trials evaluating the long-acting dapivirine intravaginal ring are encouraging and show that high levels of adherence (82% and 73%, respectively) are achievable. Given these high rates of adherence, it was surprising that the monthly dapivirine vaginal ring reduced HIV incidence rates by only 27% and 31% in the 2 respective studies. Of importance, there was no impact on HIV acquisition in women below the age of 21. An open-label posttrial access study is planned to further investigate this finding. If licensed, the product could become available as an HIV prevention option for women within 4-5 years.
Beyond Women-Initiated Technologies
The potential for a wide array of women-initiated technologies is growing as a first step for reducing women’s risk of acquiring HIV and, of importance, affording women a choice for remaining HIV uninfected. Structural, social, and behavioral factors that render women more vulnerable to HIV will need to be addressed to bridge gender disparity gaps in the longer term. In addition, the high HIV prevalence and high morbidity and mortality rates in adolescent girls and young women underscore the importance of strengthening HIV treatment services in this group. The integration of HIV prevention and treatment strategies into accessible sexual reproductive health services provides an opportunity to improve health and educational outcomes for young women regardless of HIV status. Given that adolescent girls and young women acquire HIV infection and other sexually transmitted infections predominantly from men aged 23-35 years, targeting prevention and treatment in this population will concomitantly enhance HIV prevention efforts for adolescent girls and young women. Failure to prevent HIV in adolescent girls and young women will reverse the gains made by the Global Plan to eliminate HIV infection in children and keep their mothers alive.
What strategies do you see as important for reducing HIV infection rates in women? I encourage you to post your thoughts in the comments section below. For more engaging education on treatment and prevention of HIV in women, join my colleague Catherine Hankins, MD, PhD, FRCPC, CM, and a panel of expert faculty for HIV Infection Among Women: Strategies to Address 3 Key Global Challenges, an interactive CME-certified symposium in Durban at AIDS 2016.