A new study of more than 700,000 one to 19-year olds being treated for HIV infection suggests a ten-fold increase in the number of adolescents aged 15 to 19 receiving HIV treatment in South Africa, according to results published in The Lancet HIV journal.
However, despite the rise, fewer than 50% who present for care successfully initiate antiretroviral therapy (ART).
"Despite the upswing in numbers initiating therapy, barriers persist that prevent many adolescents from starting treatment. These may include concerns about stigma, a perceived lack of confidentiality at clinics, the need for frequent visits to clinics to start and maintain treatment, and increasing responsibilities at home, particularly among those orphaned by HIV," says lead author Mhairi Maskew from the University of the Witwatersrand, South Africa. "Given the rapid growth in adolescents seeking HIV care, health systems should determine how best to meet the needs of this critical population because increasing testing and treatment among them may become critical to controlling the epidemic." 
South Africa has the largest number of people living with HIV in the world at approximately 7.2 million. Many children are born with the virus, but survive into adolescence without treatment, while adolescents also become infected via sexual transmission. Adolescent girls have the highest HIV incidence of any demographic group in the country, attributed to the gender inequality and sexual violence they face. 
The growth in the number of adolescents on treatment is due in part to the historical success of South Africa's ART program. Children who were HIV-infected as infants, prior to the widespread availability of prevention of mother-to-child transmission (PMTCT), are now surviving into adulthood on ART. At the same time, adolescents are now seeking care and starting ART at greater numbers.
Last year, the International AIDs Society-Lancet Commission warned that as the largest generation of young people ages into adolescence, it could spark a resurgence of the AIDs epidemic.  However, if the country manages to achieve the target of treating 90% of all people living with HIV, the adolescent population on antiretroviral therapy could double within five years.
For the current study, scientists tracked the number of children and adolescents aged one to 19 years tested for HIV between 2005 and 2016, using laboratory data from South Africa's National HIV Programme. They estimated the proportion receiving care and the proportion on antiretroviral therapy observed through HIV monitoring lab tests in the National Health Laboratory Service (NHLS) data. They classified the results by gender as well as according to whether the patient entered care when under 15 years old - and were likely infected at birth - or between the ages of 15 and 19, when it is likely they were infected via sexual transmission.
The authors analysed data on 730,882 patients aged one to 19 who entered the HIV program between 2005 and 2016. Among patients entering care before age 15 years, 54% were female (209,205 patients), consistent with an approximately even numbers of boys and girls becoming perinatally infected during birth or breastfeeding. However, among patients entering care aged 15 to 19 (301,242 patients), 88% were female, consistent with the much higher rates of sexually-transmitted HIV infection and higher rates of care-seeking among young women compared to young men.
Of patients who entered the HIV program during the study period, 57% (415,882 of 730,882) started to receive antiretroviral therapy and the overall numbers on treatment increased for each age group. The number of one to four-year-olds starting treatment increased by 25%, from 25,803 between 2005 and 2008 to 32,456 during 2013 to 2016. Over the same period, the number of 15 to 19-year-olds starting treatment grew from 7,949 patients in 2005 to 2008 to 80,918 during 2013 to 2016, a ten-fold increase in the number of adolescents on antiretroviral therapy.
Despite these high numbers, people entering care as adolescents had much lower rates of initiating ART than children. Just 45% of 15 to 19-year-old girls and 42% of boys who presented with HIV started treatment, compared to 68% of girls and 69% of boys aged one to four.
The authors note that some groups are not observed in their data, such as results from infants under a year old, patients accessing care in the private sector, or those who do not test and do not enter the HIV treatment program. In addition, KwaZulu-Natal is not observed prior to 2011. However, the proportions they observed initiating therapy by age category and mode of transmission do not change significantly with the inclusion of data from KwaZulu-Natal.
Writing in a linked Comment, Dr Audrey Pettifor from the University of North Carolina, USA, says: "To date there are limited evidence-based interventions to improve linkage to and retention in care for adolescents and even fewer that have been taken to scale--this must change now if we want to see reductions in new infections and alter the course of the HIV epidemic. A first step to addressing the adolescent epidemic is understanding the problem, Maskew and colleagues take an important step in highlighting that the battle against HIV is far from over and that government, donors, programs and researchers must act with urgency to develop, test and implement evidence-based interventions to prevent new infections and improve linkage to and retention in care for adolescents."
Peer-reviewed / Observational study / People
NOTES TO EDITORS
This study was funded by the National Institutes of Health, the American President's Emergency Plan for AIDS Relief (PEPFAR) and the United States Agency for International Development (USAID). It was conducted by researchers from the University of the Witwatersrand (South Africa), Boston University (USA) and the National Health Laboratory Service (South Africa).
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