therapy (ART) is associated with a substantial and sustained reduction in the
risk of sexual transmission of HIV, according to results of an observational study
published in AIDS. The research
involved people living in rural Uganda. Data were collected on viral suppression
with ART and sexual risk behaviour. Overall, virologically suppressive ART
reduced the risk of sexual transmission of HIV by 90%.
corroborate prior work describing the enormous potential of ART to prevent
transmission in HIV-endemic, resource-limited settings,” comment the authors.
A growing body of
data shows that virologically suppressive antiretroviral therapy (treatment which reduces viral load to an undetectable level) is associated
with a near-zero risk of sexual transmission of HIV.
This means that people taking antiretroviral therapy can, in theory, only transmit HIV to
sexual partners if their viral load is detectable – above 400 copies/ml.
But it is unclear
how often people taking ART have sexual encounters that involve such a risk
of HIV transmission.
team of investigators therefore designed an observational study involving 463
adults living with HIV in rural Uganda who were starting ART.
“Our goal was to
measure the potential impact and durability of ART to mitigate transmission
risk for PLWHA [people living with HIV/AIDS] on long-term treatment in an HIV-endemic, resource-limited
setting,” explain the authors.
Every three months, the study participants had their viral load monitored and answered questions about their
recent sexual behaviour, including the HIV status of their partners and
Each 90-day period
was considered to involve a risk of HIV transmission if a participant had a
detectable viral load and reported unprotected sex with a partner who was
HIV negative or whose HIV status was unknown.
Most (70%) of the
participants were women and their median age was 34 years. Median CD4 count and viral load at baseline
were 136 cells/mm3 and 126,000 copies/ml, respectively. The participants
were followed-up in the study for a median of 3.5 years, and during this time contributed a
total of 5923 study visits.
59% of participants had either detectable viral load or reported sexual behaviour
involving a risk of HIV transmission at least once. However, only 5% of participants had simultaneous viraemia and transmission risk behaviour, and this
occurred at less than 0.5% of study visits.
“ART provided a
sustained, more than 90% reduction in periods of HIV transmission risk by
imparting undetectable viral loads to individuals when risky sexual behaviour
was reported,” write the authors.
characteristics were associated with the reporting of risky sexual behaviour
while having a detectable viral load. These included younger age (p = 0.01),
higher HIV-related internalised stigma score (p = 0.04) and lower CD4 count (p
periods of potential HIV transmission risk by over 90% in a population of PLWHA
in Uganda during up to 6 years of observation time,” conclude the authors. “These
findings provide further support for the provision of ART to all PLWHA meeting
guidelines to reduce HIV transmission in HIV-endemic settings.”