Vandormael was presenting the most recent findings from a long-lasting
cohort study in north-eastern KwaZulu-Natal conducted by the African Health Research Initiative (AHRI).
It was this cohort that in 2012 provided the first evidence from a low-income
setting that getting a sufficiently high proportion of the population virally
starting to bring down the HIV infection rate.
Because this area has comprehensive HIV surveillance, part
of it was also chosen to host ANRS
12249, the world’s first study of the population-level effects of “Test and Treat”
as a strategy.
In the AHRI cohort, people are proactively tested by community health workers, who visit each
household in the catchment area, using dried blood spot technology, once a year. Between 2004 and 2015, 38,597 people have been
tested for HIV at least once and exactly 17,400 testers (45%), whose first test
was HIV negative and who have taken at least one more HIV test since then, form
the “incidence cohort”. Of these, 9908 (57%) are women.
Among men, there have been 641 new diagnoses of HIV in
28,006 person-years (overall annual incidence, 2.3%) and in women, 1915 in
40,182 person-years (4.8%).
HIV incidence was not only lower in men than in women generally, it also declined from
2.4% in 2005 to 2.05% in 2010 and then to 0.95% in 2015. From 2010 onwards this
fall was statistically significant.
In contrast HIV incidence in women during the same period increased,
from 4.2% it 2005 to 4.65% in 2010 and then 5.1% in 2015. This nearly reaches
statistical significance. There are signs of a levelling-off in the incidence rate
from 2013 to 2015, but not a decline.
Why, among a population that has seen antiretroviral therapy
(ART) coverage of those in care rise by over 60% in the last five years, have
men seen their rate of HIV infection fall by over half, while among women there has been an increase?
One explanation has been that age differences are partly to
blame. It is certainly true that HIV annual HIV incidence is still disproportionately high among
young women: currently 5.4% of girls aged 15-20 are infected with HIV per
year, 7% aged 20-25 and 6% aged 30-35. By the time women are 30, a huge
proportion of them have HIV – more than half in some areas.
Annual HIV incidence in men, on the other hand, is very low in youth – just 0.7% in boys aged 15-20 – and does not start to exceed that in women
until the ages of 35-40, when it is 3% in men and 2.2% in women.