Since 2018, the agency has mandated tracking the genetic signatures of viruses collected from people with H.I.V., a practice known as molecular surveillance.Since 2018, the agency has mandated tracking the genetic signatures of viruses collected from people with H.I.V., a practice known as molecular surveillance.Read MoreAcquired Immune Deficiency Syndrome, Disease Rates, Privacy, States (US), Tests (Medical), Viruses, Medicine and HealthNYT > Health