CDC guide on testing for HIV. Check this! Helpful.
“Screening Tests. The conventional serum test for diagnosing HIV infection is the repeatedly reactive immunoassay followed by confirmatory Western blot or immunofluorescent assay. The test is highly accurate (sensitivity and specificity greater than 99.5%), and results are available within one to two days from most commercial laboratories.
Rapid HIV testing may use blood or oral fluid specimens and can provide results in five to 40 minutes. The sensitivity and specificity of the rapid test are also both greater than 99.5%; however, initial positive results require confirmation with conventional methods.
Other FDA–approved tests for detection and confirmation of HIV infection include combination tests (for p24 antigen and HIV antibodies) and qualitative HIV-1 RNA.” AAFP
The old vs. new way of testing for HIV
The old way of testing HIV: 1) HIV Abs by ELISA w/ 2) confirmation by Western blot or detectable plasma HIV RNA (some places may still use this method.
Testing for HIV is ideally performed with a combination antigen/antibody immunoassay, which requires a blood draw. At the point-of-care, other options for testing can be performed on oral secretions or finger-stick samples.
** For HIV the difference between screening and confirmatory tests is that the screening test simply tries to check for antibodies (and antigen p24) for HIV. It doesn’t specifically differentiate HIV-1 or HIV-2. The confirmatory test differentiates between HIV-1 and HIV-2.
Labcorp HIV Testing (new way of testing HIV)
1) Screening
Lapcorp uses a combined 4th generation test that does both HIV 1/2 antibodies and P24 antigen.
Test Number 083935: Human Immunodeficiency Virus 1/O/2 (HIV-1/O/2) Antigen/Antibody (Fourth Generation) Preliminary Test With Cascade Reflex to Supplementary Testing
2) Confirmation
Test number 083955: Human Immunodeficiency Virus 1/2 (HIV-1/2) Antibody, Differentiation With Reflex to HIV-1 RNA ( also called Multispot®)
Multispot is the replacement for Western blot