Fig. 1

Venn diagram of the number of individuals in the 5 categories of difficult-to-treat HIV. Sets with less than 10 individuals are not shown. “≥ 2 VF switches” denotes people who switched therapy ≥ 2 times in relation to virologic failure, “VF12mo” people with virologic failure within the past 12 months, “AR” people with advanced resistance”, “ST” people currently on salvage therapy, and “4DR” people with 4-drug regimens