HIV TESTING AND COUNSELING

An estimated 1.2 million people in the United States are infected with HIV, including about 158,500 people who are unaware of their status. Nearly 40% of new HIV infections are transmitted by people who do not know they have the virus.

HIV testing is the first step in preventing transmission of the virus to others. HIV tests are quite accurate, but no test can detect the virus immediately after infection (CDC, 2022e).

Types of HIV Tests

There are three types of HIV tests: antibody tests, antigen/antibody tests, and nucleic acid tests (NAT).

ANTIBODY TESTS

Antibody tests detect antibodies to HIV in the person’s blood or oral fluid. Antibody tests have a window of 23–90 days before HIV can be detected after an exposure. Antibody tests that use blood from a vein can detect HIV sooner after infection than tests performed with blood from a finger stick or with oral fluid.

Most rapid tests and HIV self-tests are antibody tests. Examples of antibody tests include:

OraQuick In-Home HIV Test (self-test)
OraQuick ADVANCE Rapid HIV-1/2 (rapid test)
SURE CHECK HIV 1/2 Assay (rapid test)
(CDC, 2022e)

ANTIGEN/ANTIBODY TESTS

Antigen/antibody tests look for both HIV antibodies and antigens. Antibodies are produced by a person’s immune system following an exposure to a virus such as HIV. Antigens are foreign substances that cause a person’s immune system to activate. If a person becomes infected with HIV, the antigen p24 is produced before antibodies develop.

An antigen/antibody test performed by a lab on blood from a vein can usually detect HIV 18–45 days after exposure. There is also a rapid antigen/antibody test available that is performed with a finger stick. Antigen/antibody tests with blood from a finger stick can take from 18–90 days after exposure to detect HIV. Examples of antigen/antibody tests include:

ADVIA Centaur HIV Ag/Ab
Alere Determine HIV-1/2 Ag/Ab Combi (rapid test)
(CDC, 2022e)

NUCLEIC ACID TESTS (NATs)

An NAT directly tests for HIV in the blood. This test is recommended for those who have had a recent exposure or a possible exposure with early symptoms of HIV and have tested negative with an antibody or antigen/antibody test. The window period before detection can occur for a NAT is 10–33 days following exposure. Examples of NATs include:

Cobas HIV-1/HIV-2 Qualitative
Aptima HIV-1 Quantitative DX Assay
Alinity m HIV-1
(CDC, 2022e)

Testing Recommendations

The CDC recommends that everyone between the ages of 13 and 64 be tested for HIV at least once as part of routine healthcare.

Recommendations call for people with higher risk factors to be tested at least annually. These individuals include:

Sexually active gay or bisexual men (some of whom may benefit from even more frequent testing, such as every 3–6 months)
People who have had sex with an HIV-positive partner
People who have had more than one partner since their last HIV test
Those who have shared needles (“works”) to inject drugs
People who have exchanged sex for drugs or money
People who have another sexually transmitted disease, hepatitis, or tuberculosis

Additionally, HIV testing is recommended for:

All pregnant women
Any newborn whose mother’s HIV status is unknown
Anyone who has been sexually assaulted (If the assault is considered a high risk for HIV exposure, the person’s baseline HIV status should be established within 72 hours after the assault and the person then tested periodically as directed by healthcare personnel.)

The CDC recommends that all HIV screening be voluntary. Separate written consent for an HIV test is not recommended. A general informed consent for medical care that notifies the patient that an HIV test will be performed is recommended, and the person can voluntarily accept the test (opt-in) or decline it (opt-out).

HIV testing is mandatory in the United States for:

Blood and organ donors
Military applicants and active-duty personnel
Federal and state prison inmates
Newborns in some states

Testing Sites

HIV tests are generally available in many places, including:

Healthcare providers’ offices
Health clinics or community health centers
STD/STI or sexual health clinics
Local health departments
Family planning clinics
VA medical centers
Substance abuse prevention or treatment programs
Many pharmacies
Mobile testing vans and community events
Home testing kits available in pharmacies or online
(HIV.gov, 2022b)

These sites can connect people to HIV care and treatment if they test positive or can discuss the best HIV prevention options if they test negative.

HIV Test Results

When testing is performed in a healthcare provider’s office, a clinic, or a community setting, results will be explained and the patient given instructions about the next steps. If a rapid HIV self-test is done at home, the package material will provide the explanation of the results and instructions for the next steps, along with a contact phone number.

A negative HIV test result does not necessarily mean that the person is not infected with HIV. This is due to the window period after exposure, which varies from person to person and depends on the type of test taken. A window period refers to the time between HIV exposure and when a specific type of test can detect HIV in the body. Therefore, when a person tests negative, it does not necessarily mean the person does not have HIV. If the person is tested again after the window period, has had no possible HIV exposure during that time, and the result is negative again, the person does not have HIV.

For a positive antibody test, a follow-up test is required to confirm the results. If a rapid screening test was performed in a healthcare setting, a follow-up test should be arranged to make certain the initial result was correct. For a positive self-test, the person should visit a healthcare provider for follow-up testing. If the blood test was performed in a healthcare setting or a lab, the lab will conduct a follow-up test on the same sample as the first test (HIV.gov, 2022c).

An HIV test can also return an indeterminate, equivocal, or invalid result. This means the test result is unclear and that another test is necessary. Indeterminate results can occur in people following recent HIV infection, due to antibody cross-reaction, or because of another technical error. If an indeterminant result is not reproduced in repeat testing, it is almost certainly a false-positive reaction (Pebody, 2021).

At times, an HIV test will return a false-positive result. This is why it is essential that all patients with a positive or indeterminant screening result undergo confirmatory testing. The main cause of false-positive results is that the test has detected antibodies to a substance or infection other than HIV. HIV tests are not meant to react to other types of antibodies, but sometimes they do (Tsoi et al., 2022; Pebody, 2021).

HIV Pre- and Post-Test Counseling

HIV counseling is intended to allow people to make informed decisions based on knowledge of their HIV status and the implications of their decisions. Counseling is a gateway to prevention care, treatment, and support. Although not required, HIV counseling is often provided both pre-test and post-test, and can be done by nonmedical personnel.

Pre-test counseling can be provided in person, by prerecorded video, or by pamphlet. Pre-test counseling enables the patient to become aware of the risks and adequacy of the timing of taking the test (to avoid testing in the window period), informs the person of the benefits of having the test done, and discusses the implications of both positive and negative results. Persons are assured to have the right to refuse to take an HIV test. This information is vital for obtaining informed consent. Also, during pre-test counseling the person is encouraged to anticipate the possibility of disclosure of HIV status, for example, to a sexual partner or family, and is provided with preventive information and material.

Post-test counseling informs HIV-positive persons of their options. They are advised and referred for further care, treatment, and support services as needed. Additionally, disclosure of positive status to relevant others is discussed and encouraged, along with the provision of prevention information and material (WHO, 2023; CDC, 2021e).