This relaxed criterion turned out to be
important. The CHAMP researchers found that 40% of post-treatment
controllers had at least one viral load measurement over 400 copies/ml after
stopping ART and 31% over 1000 copies/ml. However, these viral load peaks happened
soon after ART was withdrawn (on average eight weeks, and never more than
24 weeks, after) and they then re-suppressed
their HIV.
The researchers also looked at the minority
of people who had had their viral loads monitored very intensively – once a week
on average. In this minority, transient high viral load peaks were found more
often. Two-thirds had at least one viral load higher than 400 copies/ml after
ART withdrawal, 45% over 1000 copies/ml, 33% over 10,000 copies/ml and 11% over
100,000 copies/ml.
The researchers speculate that these short
bursts of viral replication may actually contribute to the later viral suppression,
at least in some people, as they may stimulate a suppressive anti-HIV immune response.
They also note that treatment interruption
studies that have strict criteria about whether to re-start ART – typically after
just one or two viral loads over a few hundred copies/ml – may miss a lot of people
who would have gone on to re-suppress their HIV.
This pooling of studies lacks certain data, such as pre-treatment
viral loads for those treated in chronic infection, but it does find that
pre-treatment viral load in those treated in early infection was only slightly
lower in post-treatment controllers than non-controllers – about 50,000 versus
80,000 copies/ml – and their CD4 counts at ART interruption also very similar –
882 cells/mm3 for controllers and 825 cells/mm3 for
non-controllers.