evidence: The evolution that resulted in the VB variant took place during the late 1980s and 1990s in the Netherlands. It spread more quickly than other HIV variants during the 2000s, but its spread has been declining since around 2010. [...] Pursuing the BEEHIVE project’s primary aim, we identified a large number of mutations that were correlated with a substantially higher viral load. These mutations were also correlated with each other: individuals tended to have a virus with all of these mutations or none of them. This collection of mutations defines a particular type of virus, what we later came to call the VB variant (because it is virulent and part of the subtype B group of viruses). Technically, we performed a ‘principal components analysis’: we found one direction in the space of all possible mutations that was correlated with viral load. 15 of the 17 individuals we found were from the Netherlands. To make sure this finding wasn’t just a statistical fluke, we worked with colleagues at Stichting HIV Monitoring to obtain much more data from the Netherlands; we found another 92 individuals with the variant. Again, we found they had a substantially higher viral load than individuals with other HIV viruses, and we also found that their CD4 cells declined twice as fast. HIV attacks CD4 cells, gradually impairing an individual’s immune system, and the rate of this decline measures how much damage the virus is causing.