There are three main types of HIV test.
The first type of test is the HIV antibody test. This test shows whether a person has been infected with HIV, the virus which causes AIDS. Information on this page concentrates on HIV antibody testing.
The second type of test is P24 antigen testing. It is primarily used to screen the blood supply but in some places it is used for testing for HIV in individuals. P24 antigen is a protein that is part of the HIV. Early in the infection, it is produced in excess and can be detected in the blood serum by a commercial test. The P24 test can detect HIV infection before the HIV antibody test can. Therefore, P24 antigen testing is used in diagnosing HIV early in the course of infection.
The third type of test is used when a person knows that she or he is already infected with HIV. These tests show the level of virus in the blood (viral load test).
The HIV test looks for antibodies in a person’s blood. When HIV (which is a virus) enters a person’s body, special chemicals are produced. These are called antibodies. Antibodies are the body’s response to an infection. So if a person has antibodies to HIV in their blood, it means they have been infected with HIV (an exception is the case of an HIV negative baby born to a positive mother, who will retain her antibodies for some months).
Most people develop these antibodies within 3 months of infection. In rare cases, it can take up to 6 months. It would be extremely uncommon to take longer than 6 months for antibodies to develop.
Getting tested earlier than 3 months may result in an unclear test result, as an infected person may not yet have developed antibodies to HIV. The time between infection and the development of antibodies is called the window period. In the window period people infected with HIV have no antibodies in their blood that can be detected by an HIV test. However, the person may already have high levels of HIV in their blood, sexual fluids or breast milk. HIV can be passed on to another person during the window period even though an HIV test will not show that you are infected with HIV. So it is best to wait for at least three months after the last time you were at risk before taking the test. Some test centres may recommend testing again at 6 months, just to be extra sure.
It is also important that you are not at further risk of getting infected with HIV during this time period. The test is only accurate if there are no other exposures between the time of possible exposure to HIV and testing.
The only way to know for sure whether you are infected with HIV is to have an HIV antibody test. It is not possible to tell from any symptoms.
What Are the Reasons to Have an HIV Test?
Many people who have an HIV test have been worrying unnecessarily. Getting a negative result (which means you are not infected with HIV) can put your mind at rest. If your test result is positive, many things can be done to help you to cope with the HIV positive result and look after your health. If your test is positive, then
A doctor can keep an eye on your health. Many people who test positive stay healthy for several years. But if you fall ill, there are many drugs called antiretrovirals that can help to slow down the virus and maintain your immune system. You can also have medicines to prevent and treat some of the illnesses that people with HIV get. You may also have access to trials of new drugs and treatments.
If you do fall ill, the doctor is going to take your symptoms more seriously if they know that you are HIV positive.
If you know that you are HIV positive, you can take steps to protect other people. For example, by practising safe sex and informing you past sexual partners.
Knowing that you have HIV may affect some of your future decisions and plans, for example starting a family.
What Does the HIV Test Involve?
In most countries, there are many places that you can get tested for HIV. It is recommended that you get the HIV test done at a health clinic, at the doctor’s surgery, or at a specialist HIV/AIDS voluntary counselling and testing (VCT) site. When you attend to get tested, you will see a doctor, trained counsellor, a nurse or some other health professional in private. He or she will explain what the test involves and what the result means.
Normally a small sample of blood will be taken from your arm, sent to a laboratory and tested. In many countries, oral tests are also available which do not require the use of needles. The test is always strictly confidential and only goes ahead if you agree. Your personal doctor will not be told about the test without your permission. Depending on the test used, it can take anything from a few days to a week or longer to get the result back.
A rapid HIV test is also an antibody test. The advantage of a rapid test is that you do not have return to get your test result. The test results from a rapid test are usually available in approximately 30 minutes. Rapid tests are single-use, and do not require laboratory facilities or highly trained staff. This makes rapid tests very suitable for use in resource-limited countries.
What Is HIV Home Sampling?
It is generally recommended that the HIV test is done in a health care setting. However, in some countries "home sampling" kits are available. With a home sampling kit, a person can take a sample (usually a blood sample) and then sent it off to a laboratory for testing. A few days later, the person phones up a special number, gives their individual identification code, and is then given the result over the phone. If the result is positive a professional health specialist will provide emotional support for the person.
For "home sampling", the major advantages are convenience, speed privacy and anonymity. In countries where HIV tests are not free, home sampling may be a cost-effective way to get tested. But for some people the lack of face-to face counselling before and after the test may be a disadvantage.
What About Home Testing?
Using an HIV test kit at home means that the results are learned on the spot without any counselling. This type of testing is not generally recommended because of the lack of emotional support for the person, and a positive result must be confirmed by further testing at a clinic. At present, this kind of test cannot be legally sold in many countries.
Note: This information is cross-posted and slightly adapted from AVERT.org in order to emphasize some aspects refering particulary to Moldova. For more details, visual adds, updated information and primary sources, please visit AVERT.org web page.