Overview

HIV 1 and 2 testing looks for evidence of human immunodeficiency virus infection. Test choice depends on timing, symptoms and whether screening or diagnostic confirmation is needed.

What it detects

HIV-1 and HIV-2 infection, depending on the specific assay.

Sample type

Blood sample, usually serum or plasma; some point-of-care tests use blood or oral fluid.

When it may be appropriate

After possible exposure, routine screening, symptoms or partner diagnosis.

Window period considerations

Window periods vary by test. Fourth-generation tests are generally earlier than antibody-only tests; RNA testing may detect infection sooner in selected cases.

Test limitations

Very early infection may be missed. Reactive screening tests usually require confirmation.

Interpretation basics

A reactive result needs confirmatory testing; a nonreactive result may still be too early depending on timing.

Follow-up recommendations

If reactive, confirmatory testing and linkage to care are important. If exposure was recent, repeat testing may be advised.

Key points

  • Detects HIV-1 and HIV-2
  • Timing affects reliability
  • Confirmation may be needed
  • Counseling supports next steps

When to seek care

  • Possible HIV exposure
  • Routine screening
  • Positive or uncertain result