The only way to tell if you have
is to take an HIV test (usually an HIV antibody test). You cannot tell if someone has HIV or AIDS just by looking at them, and HIV cannot be diagnosed through symptoms. AIDS and
are not specific, and may be indicative of many other illnesses, which is why an HIV test is the only way to receive a definitive diagnosis.
Why should I take an HIV test?
If there is a possibility that you have been exposed to HIV, then a test is always the best option.
Many people are very frightened of taking an HIV test in case they test positive. This can mean they spend many months, sometimes even years, worrying about the possibility of having HIV, often unnecessarily. In almost every case, it is better to know your status than not to know:
If you are diagnosed as HIV negative, your mind will instantly be put at rest and you can stop worrying and get on with your life.
If you are diagnosed as HIV positive:
- You can be offered
emotional support, and advice on what to do next.
- You can have you health assessed and begin antiretroviral treatment if necessary (and available).
- You can also take measures to ensure that you protect your partner and (if you are a woman) any future children from getting HIV.
- You can be reassured that if you do fall ill, a doctor is going to take your symptoms more seriously.
- You can start to make plans for the future. Learning that you have HIV may be a shock, but it can also lead people to do amazing things that they may never have considered before!
If it is inconvenient or risky for you to take a test because of personal circumstances, you should wait until it does become possible, and in the interim, ensure that you use condoms with your partner, or take other measures to protect their health and yours.
Read more about
HIV testing and
learning that you are positive.
When should I take an HIV test?
Though a person who is infected with HIV will become infectious themselves very rapidly (within a day or so), they will normally have to wait a while before an HIV test will produce an accurate result. The length of time before an accurate result can be produced is called ‘the window period’ and will depend on the type of test they are taking.
In the majority of cases globally, the standard test that will be offered at an HIV testing centre will be an
HIV antibody test
. The HIV antibody test looks for antibodies to the virus in a person's blood. For most people these antibodies take 6 weeks to 3 months to develop. In very
rare cases, it can take up to 6 months. It is extremely rare for a person to take any longer then 6 months to develop detectable antibodies.
Getting tested before 3 months have elapsed may result in an unclear test result, as an infected person may not yet have developed antibodies to HIV. These 3 months are known as the 'window period'. So it is best to wait for at least 3 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, though in most cases this is not necessary.
If you are waiting to take an HIV antibody test, it is vital that you do not put yourself at risk through further exposures to HIV during this time period. This means you should practise safe sex and not share needles. Any further exposure to HIV may mean a negative HIV test result is not accurate (unless of course you wait another three months after this exposure).
The vast majority of HIV tests that are given in clinics are antibody tests, though other types of test may be available in some clinics. In some countries, such as the UK, fourth generation tests (tests that combine a p24 antigen test with a standard antibody test) are the primary recommendation. These have a smaller window period, estimated between 11 days and 1 month.
I don't think I can wait three months for a test - could I get an accurate result more quickly?
The HIV antibody test is the most commonly used test, and generally provides the most reliable results. However, other tests that detect the presence of HIV directly are available. Tests such as the
HIV PCR test
can usually give accurate results within three weeks of infection. However, not all clinics will offer these tests, and you may have to pay for them if they do. You should ask you healthcare provider for more information if you wish to take an HIV test before three months have elapsed.
What is an HIV antibody test?
An antibody test is the most common type of test used to diagnose HIV in individuals. This test shows whether a person has been infected with HIV by looking for HIV antibodies in a person's blood. When HIV enters a person's body, special proteins are produced, which are known as antibodies.
If a person has specific antibodies against 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). Depending on the clinic, the test results from an antibody test can come back in under an hour (in the case of
rapid HIV antibody tests
), or may take a few days or weeks (in the case of standard antibody tests).
When are antibodies detectable?
Antibodies react to the presence of HIV. How soon they are detectable varies between people, but by 3 months after exposure, antibody tests will detect them. Seroconversion is the term used to describe when antibodies have become detectable.
A persons 'viral load' can go up or down throughout their life, but taking HIV antiretroviral treatment can ensure very low viral loads. When this happens it is known as an 'undetectable viral load'. However, HIV antibodies will continue to be produced in reaction to the low levels of the virus. HIV antibody tests will therefore always detect HIV infection (give a positive result), regardless of a persons viral load, as long as 3 months have passed since exposure.
How is the HIV antibody test performed?
When you attend to get tested you will see a doctor, trained counsellor, nurse or health care worker in private. He or she will explain what the test involves and what the result means, or give you a leaflet that explains these things. Normally a small sample of blood will be taken from your arm, and will be tested there and then, or will be sent to a laboratory and tested. In some 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.
Sometimes you will have to make a second appointment to get your results, as many doctors prefer to give test results in person. In some countries, negative test results may be given out over the phone or via a text message or e-mail if you give your permission for this to happen. People with positive or indeterminate (unclear or unreadable) results will always be asked to make a face-to-face appointment so they can receive counselling from a trained professional.
What is a rapid test?
A rapid HIV test uses the same technology as other tests. The advantage of a rapid test is that you do not have to return to get your test result - results are usually available in 20-40 minutes. Rapid tests are single-use and do not require laboratory facilities or highly trained staff. This makes rapid tests particularly suitable for use in countries with limited resources. Though the test is 'rapid' at providing results, there will still be a window period, depending on what type of test it is.
What is a p24 antigen test?
A p24 antigen test is another type of HIV test. Antigens are the substances found on a foreign body or germ that trigger the production of antibodies in the body. The antigen on HIV that most commonly provokes an antibody response is the protein p24.
p24 antigen tests are not usually used for general HIV diagnostic purposes, as they have a very low sensitivity and they only work before antibodies are produced in the period immediately after HIV infection. Their advantage is that they have a smaller window period, which is estimated to be between 11 days and 1 month.
When are antigens detectable?
Early in HIV infection, p24 is produced in excess and can be detected in the blood serum. Antigen tests can detect them at about 10 days after initial exposure, when concentrations of the virus are high.
Antigens trigger the production of antibodies, which attach themselves to the p24 antigen. The p24 antigen then becomes undetectable when the antibody has attached to it.
What are NAT, DNA, RNA and PCR tests?
HIV tests that detect the genetic material of HIV itself (rather than antibodies or antigens) are known as PCR tests. PCR stands for Polymerase Chain Reaction and is a common way of testing for a variety of different organisms. The overall process of extracting and amplifying the genetic material of an organism (in this case HIV) and then testing for it with a PCR test is called Nucleic-acid Amplification Testing or NAT. NAT tests generally take two forms: DNA PCR tests and RNA PCR tests.
RNA PCR tests are most frequently used for screening blood donations and donor organs for HIV, while DNA PCR tests are used for testing newborn babies born to HIV positive mothers. Both types of test can be used to measure the amount of virus that is present within a person's body (when they will usually be referred to as 'viral load' tests). NAT is sometimes also offered for diagnosing individuals, but because it is costly and complicated to perform, antibody testing is far more common in testing clinics.
NAT generally gives positive results much sooner than standard antibody testing would, making it useful in situations where early diagnosis is necessary. An RNA PCR test will produce a positive test result within two to three weeks. A DNA PCR test will provide positive results within three to four weeks (sometimes sooner). As long as the recommended amount of time has elapsed before taking the test (people taking the test for personal diagnosis should ask their testing clinic if they are unsure), the test will be able to give a very accurate result. False positive results are more common than false negatives due to the PCR test's sensitivity, so all positive results must be double checked using a standard antibody test.
Can I get tested without visiting a clinic?
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 or oral fluid sample), send it to a laboratory for testing and then a few days later phone up for the results. If the result is positive then a professional counsellor will provide emotional support and referrals. For home sampling, the major advantages are convenience, speed, privacy and anonymity.
There is one company in the USA that offers an FDA-approved home sampling kit for HIV. Many home sampling kits that have not been approved by the FDA are being marketed online. One company in the UK offers home sampling services using oral fluid instead of blood.
Are rapid over-the-counter HIV testing kits recommended?
In July 2012 the FDA approved rapid HIV testing kits for over-the-counter sale. The test, manufactured by Orasure Technologies
, detects the presence of HIV antibodies in the body.
The FDA’s recommendation of selling HIV testing kits over-the-counter is likely to be repeated by many countries outside the U.S. and will go some way towards addressing the barriers that prevent people from accessing HIV testing and increasing the number of people that know their HIV status.
Many people remain unaware that they are infected with HIV, which can affect their health and increase the risk of onward transmission. The benefit of over-the-counter HIV testing kits is that they overcome a number of issues that may make individuals reluctant to test in a healthcare setting. Over-the-counter or home HIV-testing kits are more confidential and convenient than visiting a healthcare clinic. The ability to take an HIV test at home, without visiting a healthcare clinic is likely to appeal to many people.
This form of testing will increase the number of people that know their status, which will enable them to access treatment earlier. The test itself is a mouth swab, which is 92% accurate – so there is a small risk that the result is not correct.
It is important, therefore, that people using a home-testing kit should have a follow-up test from their doctor.
What is the difference between anonymous and confidential testing?
Confidential testing means that the results of any HIV test performed will not be revealed to anybody except designated clinic staff, and in some cases, specific public health officials. Confidential testing will usually require a person to give their details (name, age, address) to the clinic performing the test. They then have to contact or return to the clinic after to get the results (unless a rapid test is used). In the UK most confidential testing is done at Genito-Urinary Medicine (GUM) or sexual health clinics. The clinics are legally bound to not reveal personal details and test results. GPs and private doctors also perform HIV tests, but the fact a person has had an HIV test, and the results, will appear on their medical records. In other countries, such as America, clinics have to notify public health officials of a person’s personal details if they test positive for HIV. In cases where an individual does not want their name associated with their test, anonymous HIV testing may also be offered. Anonymous testing can either be ensured by a patient giving a false name and address (which can create difficulties if a person tests positive and needs to be informed), or can be specifically requested. In the US, a patient requesting anonymous testing will be given a unique identifying code. No official record of them being tested will be made and no identifying details will be passed on to public health authorities in case of a positive result. It is then up to the person being tested to contact the clinic/laboratory for the results.
What is anonymous unlinked HIV testing?
Anonymous unlinked HIV testing is a form of testing used worldwide for research and surveillance purposes, most commonly among pregnant women. Blood samples taken routinely for other tests are additionally tested for HIV. No personal information is taken and there is no way of linking the test results back to the person being tested. The results have no direct individual use but can provide important information for estimating HIV prevalence and incidence.
If I test HIV negative, does that mean my partner is HIV negative too?
No. Your HIV test result reveals only your HIV status. Your negative test result does not indicate whether or not your partner has HIV. HIV is not necessarily transmitted every time you are exposed to it. Therefore your HIV test should not be used as a method to find out if your partner is infected.
I'm pregnant - should I have an HIV test?
In many countries you will be offered an HIV test when you are pregnant as part of your antenatal care. It is your decision whether to take it or not. However, if you are infected with HIV and do not know it, you cannot benefit from treatment that can prevent HIV from being passed onto your baby. If your test result is positive, this means that you could pass HIV to your baby during pregnancy, during birth or by breastfeeding. However, there are certain things a woman can do to minimise the risk of HIV being passed to her child. These include:
- taking antiretroviral drugs during pregnancy
- taking antiretroviral drugs during labour
- choosing caesarean section as the method of delivery
- giving the baby a short course of antiretroviral therapy after birth
- formula-feeding rather than breast-feeding.
AVERT.org has more about
preventing mother-to-child transmission of HIV,
HIV testing in pregnancy and
HIV and pregnancy.
Can my baby have an HIV antibody test?
During pregnancy and breastfeeding, a mother will pass on many essential antibodies to her baby to enable the child to fight infection. All babies born to mothers with HIV are therefore born with HIV antibodies (though not necessarily HIV itself). If an HIV antibody test is given to a newborn baby then it will always give a positive result if the mother is infected with HIV, regardless of whether the baby actually has HIV. Babies who are not infected lose their antibodies by the time they are around 18 months old. So it is only after your baby is 18 months old that the HIV antibody test will give an accurate result. However, most babies can be diagnosed as either infected or uninfected by the time they are 3 months old by using a different test, called the DNA PCR test. The PCR test is more sensitive than the HIV test and looks for the presence of HIV itself, not antibodies. If you are worried that your baby may have been infected, you should speak to your doctor. AVERT.org has more about
HIV and pregnancy
How long must I wait for my results?
Depending on the test used and where it is done, it can take anything from a few minutes, to a few weeks to get the result back. You should ask your doctor at the time of testing how long the results will take. For more specific information about results, see the different test sections above.
Do I need to have an HIV test to visit or work in another country?
Some countries do not allow people with HIV to enter the country, or require HIV testing or proof of a negative test result before they will issue a visa or work permit. A full list of international immigration regulations related to HIV can be found on the National AIDS Manual's
'countries and their entry restrictions'
Will having a positive HIV test result affect my ability to get insurance or a mortgage?
If you find that you are infected with HIV, you may find it very hard to get life insurance from a regular insurer in most countries. This may in turn affect your ability to get a mortgage. If you discover you have HIV and need to get a mortgage, you should opt for a provider that does not require you to take out life insurance. In some countries with high HIV prevalence, such as South Africa, you may be able to find a specialist insurer that will provide you with cover. Any insurance you had before you were tested will not normally be affected if you test positive. If you take a test and discover you are not infected, this should not affect your ability to get insurance either. These days, you should not be asked if you have ever had an HIV test and tested negative. Many countries now have insurers that will provide travel insurance to HIV positive people. You should contact your local HIV and AIDS organisation for more information if you are planning to go abroad.
Can an employer ask me to have an HIV test?
This depends on the country you are in. In many countries, it will only be legal for employers to test employees if they do a job that requires them to have no serious health problems (such as working in the armed forces for example). If you are asked to take an HIV test for work that you don't believe is necessary, you should contact a legal advisor, or an AIDS organisation in your country for advice.
Will I be tested for HIV if I give blood?
Yes. All developed countries and most developing countries test donated blood (and organs) for HIV and other infections such as hepatitis, to prevent transmission to recipients. Becoming a blood donor is the most common reason for being tested for HIV in the UK and USA. If the test result is positive, the blood donation service will inform the person and advise them what to do next. In some low-income countries, a lack of resources means that donated blood isn’t routinely tested for HIV. If you are worried you might have HIV, it is better to visit an HIV testing clinic to receive a test, than to donate blood in the hope that you will be told.
Do tests detect HIV-2 and all subtypes of HIV-1?
All antibody tests should detect the most common subtypes of HIV-1. The majority of HIV tests will also now detect HIV-2 and all but the very rarest of HIV-1 subtypes (usually only found in endemic areas in West Africa). A test that specifically detects the rare HIV-1 group O is also now available, though in most cases, a standard antibody test would identify a group O infection. For detailed information, see our page about
Do flu vaccinations or pregnancy cause false positive HIV test results?
There are a number of factors, including recent flu vaccination and multiple pregnancies, that may make people more likely to receive a false positive result in the initial screening test for HIV, though such results are still unusual. Confirmatory tests such as the Western blot are used to distinguish between these false positives and genuine HIV infection. The risk of a false positive during confirmatory testing is extremely tiny - around 1 in 250,000 for the Western blot, for example.
What is an indeterminate Western blot result?
The Western blot test is used as a confirmatory test in the US and some other countries. This test can separately detect antibodies to various HIV proteins. If several types of antibodies are detected then the result is positive; if no antibodies are detected then the result is negative. If the test appears to show only one or two types of antibodies then the result is called indeterminate, or inconclusive. There are two main reasons why this can happen. Firstly, it may be that the person has only recently become infected with HIV, and has not developed a full immune response. Secondly, the test may be showing a weak reaction to other antibodies unrelated to HIV. An indeterminate result indicates that further testing is required. Either the Western blot may be repeated a few weeks later, or a different test (such as PCR) may be used.
What are the differences between 'mandatory', 'voluntary' and 'routine' HIV testing?
Mandatory HIV testing means that you have no choice over whether to be tested or not. Essentially it is a compulsory test that you cannot refuse. Voluntary testing on the other hand is just that: voluntary. It means you have to actively and freely choose to take an HIV test. Routine testing is an HIV test that is offered to everyone within a certain population (for example, pregnant women, or people within a certain age group) on a routine basis. It is also referred to as 'opt-out' screening, which means the test is automatically performed unless the individual concerned raises an objection and 'opts out'. Both voluntary and routine HIV tests require a person’s full written or verbal consent. Because it restricts freedom of choice, and can result in stigmatisation and discrimination for anyone who tests positive, mandatory testing is generally seen as an unsuitable way of combating HIV and AIDS. For screening a certain population for HIV, routine opt-out policies are therefore considered to be more effective from both a public health and an ethical point of view.