What tests are used to diagnose HIV?« Back to Previous Page

Worried about HIV? The biggest mistake people make is testing too early or choosing the
wrong test.
This guide explains clearly which test to do and when.
Which HIV Test Should You Do?
• Within 2 weeks: HIV RNA PCR
• 2–6 weeks: 4th Generation Test (Best choice)
• After 6 weeks: Highly reliable (~99%)
• Rapid/self tests: Repeat at 12 weeks
Types of HIV Tests
1. HIV RNA PCR (Early Detection Test):
Detects the virus directly.
Window period: 10 days.
Best for very recent exposure.
Note: Repeat testing with HIV 4th gen test is mandatory in accordance with the window
period. This test is not to be taken as conclusive test.
2. 4th Generation HIV Test (Gold Standard):
Detects antigen + antibodies.
95% detection: 4 weeks (highly accurate)
99% detection: 6 weeks (almost conclusive)
Most recommended test.
3. 3rd Generation HIV Test (Antibody Only):
Detects antibodies only.
Reliable after 8–12 weeks.
Used in rapid/self-testing.
4. Western Blot Test (Older Confirmatory Test):
The Western Blot test was traditionally used as a confirmatory test for HIV.
It detects antibodies to specific HIV proteins.
Window period: Similar to antibody tests.
Important Points:
• It is no longer routinely used in modern HIV diagnosis.
• It has been replaced by more accurate and faster confirmatory tests (HIV-1/2
differentiation assays).
• It may sometimes give indeterminate results, especially in early infection.
Current practice uses a combination of 4th generation tests followed by confirmatory
assays instead of Western Blot.