Picture that wily little virus taking refuge from your meds, and you'll grasp this term. HIV drugs attack only HIV-infected cells that are actively dividing—when responding to another infection, say. But meds can't hit HIV in resting immune cells. So the meds can't clear the virus from our bodies.

“HIV sanctuary” entered our vocabulary when researchers began trying to lure the lurking virus from its hideaways so the drugs could attack it. So far, that strategy hasn't worked, because as drugs enticed hidden (latent) HIV to emerge, they also stimulated the immune system, creating more CD4 cells for the virus to infect.

Soon you'll hear the term more frequently. In June, scientists showed just how these reservoirs keep HIV going, possibly laying the basis for a future strategy to coax HIV from its lairs without upping immune activity. Then, let's hope, the hot term will be “HIV eradication.”