This is the blood test used to determine HIV infection. HIV or Human Immunodeficiency Virus is the virus that causes AIDS or Acquired Immune Defficiency Syndrome.

When most people talk about getting an HIV test they are referring to a blood test that looks for antibodies to HIV and does not directly test for the virus itself.

The most common HIV antibody test procedure is really a combination of two tests: a screening test and a confirmatory test. Screening consists of either an ELISA (Enzyme Linked Immuno-Sorbent Assay) or an EIA (Enzyme Immunosorbent Assay) test. The confirmatory test is called the Western Blot test. Only blood samples that test positive repeatedly in the Screening phase are confirmed.

It is important to understand the latency in an antibody-based testing system. Antibodies are the immune system's response to foreign intruders in the body. The amount of time for an individual's immune system to produce antibodies to the HIV virus varies from person to person. The current testing technology described above will detect antibodies to the HIV virus 99% of the time within 3 months of infection.

This latency factor means that the HIV test can give a misleading negative result (which indicates no HIV antibodies were detected hence no HIV infection is present) if the test is conducted less than three months from the initial date of infection. To state this another way, if a person has unsafe sex or shares needles and gets an HIV test 10 days later, if the test comes back negative it does not necessarily mean that this person was not infected with the HIV virus 10 days ago. To be 99% certain that HIV infection did not occur, this person would need to be tested no less than 3 months from the date of the risky activity in question.


Material from the Seattle and King County Public Health website as well as pamphlets produced by the Northwest AIDS Foundation and the Sisters of Perpetual Indulgence was used to create and fact check this node. Please msg me with errors or significant omissions.

This node is a work in progress.

HIV tests cause a lot of anxiety. A lot of this is due to the ignorance is bliss philosophy: some consider it better not to know. This situation is not exactly enhanced by insurance companies, who consider the existence of a HIV test on the customer's medical records evidence of a high-risk lifestyle, and so charge higher life insurance premiums. Last, but not least, is the fact that they involve big needles and two test tubes of blood: not good if you have a phobia of either.

Bringing the subject up with a doctor or partner is also a little embarassing: wanna scream 'I HAVE A RISKY SEX LIFE!!!!!' from the rooftops? Didn't think so. Don't stress. Doctor-patient confidentiality, for a start. And partners? Well. Suggesting that they should get a test can be insulting, while telling them you want one may freak them out. But hey: embarrassment versus early treatment of an often-fatal disease really shouldn't be a hard choice.

Call me a fascist, but I've always believed that, if you are entering a sexual relationship and you think you could be HIV-positive, there is no excuse not to get tested. Your own body and safety you can ignore. Someone else's you cannot, particularly given recent rulings that infecting someone with HIV can amount to assault or manslaughter.

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