Diagnosis of HIV: All You Need to Know

The diagnosis of HIV consists of carrying out specific tests that detect the infection with a wide margin of safety. Let's know what they are and some tips about it.
Diagnosis of HIV: All You Need to Know

Last update: 26 July, 2021

According to data from the Joint United Nations Program on HIV / AIDS (UNAIDS), “in 2020, around 6 million infected people didn’t know they had the virus.” The disease can go unnoticed in its early stages as a simple flu, and the diagnosis of HIV is complicated if there are no direct indications that you have this STD.

It’s widely accepted among specialists that the prognosis of the disease is better when it’s detected early. In this way, doctors can start treatment aimed at stopping its development, as well as attempting to avoid new infections and reduce the complications associated with the infection. In this article, we’ll show you the HIV tests that are currently available.

How do you carry out the diagnosis of HIV?

As Stanford Health Care tells us, the diagnosis of HIV revolves around laboratory tests designed to detect the presence of the infection in the body.

The specialist, or the patient themself, will resort to them when they suspect that the symptoms may be caused by the virus. The tests are intended to find antibodies or antigens associated with the infection.

They’ll use blood, saliva, or urine tests for this. The final diagnosis isn’t given until there’s objective confirmation, so sometimes several tests are required before the professional communicates the results to the patient.

Following the guidance of the University of California San Francisco Medical Center (UCSF Health), the diagnosis of HIV is made based on:


HIV diagnosis includes the use of molecular techniques.
The ELISA study, the most widely used for the diagnosis of HIV, is based on the interaction between antigens and antibodies.

The enzyme-linked immunosorbent assay, also known as ELISA, is the standard test for detecting unique antibodies during HIV diagnosis.

Researchers support its use over other laboratory options, although it has several limitations. The first and most important one is how long you have to wait to get the results.

For this reason, it has been replaced by other options that, although not as sensitive, allow a safe detection of the infection, through blood extraction.

Rapid clinical screening tests

This consists of rapid examinations carried out within the hospital environment. Most allow access to results in less than half an hour and are performed by taking a sample of saliva (preferably), urine, or blood from the finger. Studies certify its effectiveness, especially to prevent patients from having to come back to get the results of slower tests.

Those used in this context, as indicated by the Centers for Disease Control and Prevention (CDC), are combined antigen and antibody tests. It’s a very useful alternative, as it can detect infections that occur after 18 days of infection.

A variant of this test is also available under a more meticulous analysis that takes a couple of days.

Rapid tests at home

There are many home tests that you can use to diagnose HIV. It’s a more private option that, even though it has a lower sensitivity, can help to rule out or partially confirm suspicions. The Food and Drug Administration (FDA) has only approved one for this context, the so-called OraQuick.

Results are available in 20-40 minutes, samples don’t need to be sent to a laboratory, it can be performed without prior knowledge, and is available online for those over 17 years of age. Whether you obtain a positive or negative result, you should corroborate it with other detection options from the specialist.

Nucleic Acid Testing (NAT)

The NAT test can detect infections that have occurred as early as 10 days after infection (on average). It operates by detecting the RNA of the virus with results available in a couple of days.

Although it’s very safe, it isn’t part of the standard procedure as it’s a somewhat expensive test. Still, it can be very helpful for patients who suspect they have recently contracted the infection.

If the result is positive in any of the above tests, the specialist will order a complete blood count and specific tests to assess the status of some organs (such as kidneys and liver).

It isn’t uncommon for tests to be carried out to detect new or past infections that may be made worse by an HIV infection. For example:

  • Tuberculosis
  • Hepatitis A, B, and C
  • Syphilis

Similarly, drug resistance tests can be applied so that the specialist is sure of the efficacy of the treatment to be implemented – all of this in the event that the result is positive.

HIV diagnosis questions and answers

As a complement to what we have already explained, we’d like to briefly answer some frequent questions about the diagnosis of HIV:

Why should I get an HIV test?

It’s the only safe, fast and viable way to rule out or confirm the infection of the virus in the body. It’s normal to feel nervous about it, but remember that, even if the result is positive, the disease can be treated today to such a point that few patients will actually develop full-blown AIDS in the future.

In view of this, an early diagnosis is of great help in order to avoid complications from the infection. The longer it’s delayed, the greater the side effects. Remember that, during the first months those infected are more likely to transmit the disease. Getting a diagnosis will thus help to prevent contagion between your sexual partners.

Who should have an HIV test?

HIV diagnosis is made more often in certain people
Not using condoms during sex can greatly increase the risk of acquiring an STD. Therefore, people who do so should have diagnostic tests constantly.

Researchers recommend testing the following groups for frequent testing for HIV:

  • People who have sex without condoms
  • People with a very active sexual life, specifically those who usually have several partners a year
  • Pregnant women (HIV can infect the fetus)
  • Those who already have a diagnosed STD
  • Those who use recreational drugs, especially those of the injectable type

In addition to these, the CDC recommends routine testing of young people and adults, even if they’re not part of the risk groups. In the cases outlined in the list, it’s recommended that you take a test at least once a year.

When should I carry out the HIV diagnostic process?

It usually takes a couple of weeks or even months before the body shows the first physiological changes to alert you to the presence of an HIV infection. Therefore, we recommend that you wait four weeks before carrying out the initial tests, despite there being tests that, in certain contexts, allow detection after 10 days of infection.

The reason for this is that the precision and sensitivity increases the longer you wait, and this allows you to obtain more reliable results. Testing two or three days after the infection is suspected will give negative results, even if the person is infected.

What do I do if the results are negative?

As we have mentioned, the fact that you have obtained a negative result doesn’t necessarily mean that you don’t have the infection.

If your suspicions are very strong (for example, you have had sex with an HIV-positive person who isn’t in treatment), then you should wait a couple of weeks and repeat the test again. If this is negative, it’s worth opting for a third confirmation.

In the process, avoid having sex or sharing syringes until you get the results.

What do I do if the results are positive?

Just as tests can return false negatives, there’s also the possibility of false positives. This is more likely if you have opted for a quick test.

The results must be corroborated with a second test (such as Western Blot) and, if the results are positive, then a specialist will consider the available treatment options. In turn, this will be complemented by a plan to prevent the spread of the virus.

  • Arora, D. R., Maheshwari, M., & Arora, B. Rapid point-of-care testing for detection of HIV and clinical monitoring. International Scholarly Research Notices. 2013.
  • Mehra, B., Bhattar, S., Bhalla, P., & Rawat, D. Rapid tests versus ELISA for screening of HIV infection: our experience from a voluntary counselling and testing facility of a tertiary care centre in North India. International Scholarly Research Notices. 2014.
  • Sands, A. Annex 7: diagnostics for HIV diagnosis. 2015.

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