HIV Infection Testing Methods
Testing methods to determine HIV infection include antigen-antibody simultaneous detection methods, rapid test methods, antigen detection methods, and genetic detection methods
HIV Antigen-antibody Simultaneous Detection Method
Detection timing
Antigen testing detects the virus’s proteins, and antigen detection is possible around 2 to 3 weeks after infection, while antibodies can be detected about 3 to 4 weeks after infection.
Application
It is a highly sensitive test method that simultaneously detects HIV antigens and antibodies, widely used globally, and is convenient; however, due to the possibility of false-positive reactions, confirmation tests with methods like Western Blot are necessary.
HIV Rapid Test Method
Detection timing
The rapid tests distributed in the country detect only HIV antibodies and can be detected 6 to 8 weeks after infection.
Application
HIV rapid tests can be performed without testing equipment and provide results within 15 to 30 minutes, making them useful; however, they have lower sensitivity compared to tests using equipment, and during the "window period" of antibody formation, blood may be inaccurately judged as negative. Window period: The period it takes for antibodies to form after a viral infection, during which antibodies can be detected in about 20 to 25 days, although in some cases this period may be extended.
- Positive reaction: Confirmation testing is necessary using Western Blot or genetic detection methods.
- Negative reaction: Re-testing is recommended 12 weeks after recent exposure to the source of infection.
HIV Antigen Detection Method
Detection timing
It detects viral proteins, allowing for antigen detection approximately 2 to 3 weeks after infection.
Application
Antigen testing is possible during the early phase of infection known as the “window period,” but as antibody levels increase, the amount of detectable antigens decreases relatively. It can be used along with genetic detection methods for the confirmation of early-stage infections.
HIV Genetic Detection Method
Detection timing
It detects HIV genes, allowing for virus detection approximately 11 days after exposure.
Application
In addition to confirming early infections, it is useful for newborn screening, monitoring antiviral therapy, and blood donor testing, but the testing cost is high.
Free HIV testing is available without disclosing personal information such as name, according to one’s preference.
What is the window period?
- Testing immediately after sexual contact with an infected person may not confirm HIV infection. In other words, when a pathogen (virus) enters the body, immune antibodies are formed to combat it. The period from the moment of infection to the formation of these antibodies is referred to as the “window period.”
- In Korea, taking into account the HIV antibody window period, it is recommended to schedule testing as follows to confirm one's infection status more quickly and receive timely treatment.
Testing should be done approximately 4 weeks after exposure, and if the test result is negative, the enzyme immunoassay (EIA) is recommended to be repeated 6 weeks after the recent exposure, while other testing methods should be repeated 12 weeks later.