HIV: Testing, Treatment, and U=U

Understanding HIV

What Is HIV?

Human Immunodeficiency Virus (HIV) is a virus that attacks the body's immune system, specifically CD4 T-cells (also called T-helper cells), which coordinate the immune response to infections. Without treatment, HIV gradually destroys these cells, weakening the immune system until it can no longer fight off infections and cancers that a healthy immune system would handle, a condition called AIDS (Acquired Immunodeficiency Syndrome).

AIDS is not a diagnosis a doctor gives lightly. By definition, AIDS occurs when CD4 T-cell count drops below 200 cells per cubic millimeter of blood, or when a person develops one of the AIDS-defining illnesses listed by the CDC. With modern treatment, the overwhelming majority of people diagnosed with HIV today will never develop AIDS.

HIV vs. AIDS: A Critical Distinction

HIV is the virus. AIDS is the most advanced stage of HIV disease. You can have HIV for decades without developing AIDS, especially if you are on treatment. Many people use the terms interchangeably, which creates stigma and misinformation. The accurate language is: a person is living with HIV, or a person has HIV. Referring to someone as "having AIDS" when they are on treatment and healthy is both medically inaccurate and stigmatizing.

Transmission

How HIV Is and Is Not Transmitted

HIV is transmitted through specific bodily fluids from a person who has HIV. The virus must come into contact with mucous membranes (like those inside the rectum, vagina, or mouth), damaged tissue, or be directly injected. HIV is not spread through casual contact.

HIV Can Be Transmitted Through:

Blood (including from shared needles, syringes, or equipment)
Semen and pre-seminal fluid (pre-cum)
Rectal fluids
Vaginal fluids
Breast milk
During pregnancy or childbirth (from parent to child)
Needlestick injuries (occupational exposure)

HIV Cannot Be Transmitted Through:

Hugging, shaking hands, or touching
Sharing food, dishes, or utensils
Saliva, tears, or sweat (unless mixed with blood)
Air or water
Mosquitoes or other insects
Toilet seats or doorknobs
Kissing (no risk unless both people have open mouth sores or bleeding gums)

Estimated Per-Act Transmission Risk (without prevention methods)

Exposure Type	Estimated Risk Per Act	Level
Receptive anal sex (being the bottom)	1.4% (1 in 72)	Highest
Insertive anal sex (being the top)	0.11% (1 in 909)	Moderate
Receptive vaginal sex	0.08% (1 in 1,250)	Moderate
Insertive vaginal sex	0.04% (1 in 2,500)	Lower
Receptive oral sex (performing)	0.04% or less	Low
Needle sharing (injection drug use)	0.63% (1 in 159)	High
Needle sharing (undetectable source)	Effectively 0	U=U applies
Sex with someone undetectable on treatment	0	U=U: Zero Risk

Source: CDC HIV Risk Behaviors, 2014 meta-analysis; updated with U=U evidence from PARTNER2, 2019

Risk is Not Fixed

Per-act risk estimates above assume the HIV-positive partner has a detectable viral load, that no prevention methods (condoms, PrEP) are being used, and that no other STIs are present. Each of these factors significantly changes risk. An STI like gonorrhea or syphilis can increase transmission risk 2 to 8 times. Conversely, an undetectable viral load reduces risk to zero, as described in the U=U section below.

Know Your Status

HIV Testing: Your Most Important Tool

The CDC recommends that every person aged 13 to 64 get tested for HIV at least once in their lifetime. For sexually active gay and bisexual men, the CDC recommends testing at least once a year, and every 3 to 6 months for those with multiple partners. Knowing your status is the foundation of every other HIV prevention and treatment decision.

There are currently three main types of HIV tests. The test type determines the window period: the time after infection when a test can reliably detect HIV. Testing during the window period may give a false negative result.

4th Generation Antigen/Antibody Test (Ag/Ab)

Detects both HIV antibodies and the p24 antigen (a protein produced by HIV itself during early infection). The most sensitive test available. Recommended as the first-line test by CDC. Can detect HIV 18 to 45 days after exposure.

Window Period: 18-45 days | Lab Blood Test

Rapid Antibody Test

Detects antibodies to HIV in blood or oral fluid. Results in 20 minutes. Available at many clinics, health departments, and community organizations. Does not detect p24 antigen, so has a longer window period. A rapid oral test has the longest window period.

Window Period: 23-90 days | Rapid (20 min)

HIV Self-Test (Home Test)

The OraQuick In-Home HIV Test detects antibodies from oral fluid and gives results in 20 to 40 minutes. Available at pharmacies and online without a prescription. Only FDA-approved home test. A negative result should be confirmed with a lab test if you tested within the window period.

Window Period: Up to 90 days | Home Use

Free HIV Testing Locations

Free HIV testing is available nationwide at community health centers, LGBTQ+ health organizations, Planned Parenthood locations, and health departments. The CDC's GetTested.cdc.gov locator lets you search by zip code for free or low-cost testing sites. Many sites offer confidential and anonymous testing. Some offer self-collection kits by mail. You can also order free HIV home test kits through select programs and state health departments.

A Positive Test is Not the End: It Is the Beginning of Treatment

If your HIV test comes back positive, you will be asked to take a confirmatory test, as false positives can occur. If confirmed, you will be connected with an HIV specialist to begin antiretroviral treatment (ART). Starting treatment quickly is the single most important thing you can do for your long-term health. People who start treatment promptly, before their immune system is significantly damaged, achieve the best long-term outcomes, including a normal life expectancy.

Scientific Consensus

Undetectable = Untransmittable (U=U)

A person living with HIV who is on effective antiretroviral treatment and has an undetectable viral load cannot transmit HIV to sexual partners. This is not an opinion or a hopeful estimate. It is a scientific fact, established by three landmark clinical trials involving tens of thousands of couples followed over many years. Zero transmissions occurred from partners with an undetectable viral load across more than 75,000 condomless sex acts.

The Science Behind U=U

HPTN 052 Trial (2011)

A clinical trial across 9 countries studying 1,763 serodifferent couples (one partner HIV-positive, one HIV-negative). Early antiretroviral treatment reduced HIV transmission by 96%. The study was stopped early because the benefit was so overwhelming it was considered unethical to continue the delayed-treatment arm. This was the first major evidence that treatment as prevention works.

PARTNER1 and PARTNER2 Studies (2014-2018)

European studies following serodifferent gay and straight couples who had condomless sex while the HIV-positive partner was on treatment and virally suppressed. Across PARTNER1 and PARTNER2, over 75,000 condomless sex acts were studied. Zero linked transmissions occurred from partners with an undetectable viral load. Published in JAMA in 2016 and The Lancet in 2019.

Opposites Attract Study (2016-2019)

Australian study specifically focused on gay male serodifferent couples. Over 16,000 condomless sex acts were analyzed. Zero linked transmissions. Confirmed the results of PARTNER for gay men specifically, a population that was underrepresented in earlier research.

What "Undetectable" Means

An undetectable viral load means that standard HIV tests cannot detect the virus in the blood, typically defined as fewer than 200 copies of HIV per milliliter of blood (some labs use 50 or even 20 copies as their threshold). This does not mean HIV is gone from the body, but it does mean the virus is suppressed to a level where sexual transmission cannot occur. Most people on consistent ART reach an undetectable viral load within 3 to 6 months of starting treatment.

U=U has been endorsed by the WHO, CDC, NIH, British HIV Association, European AIDS Clinical Society, and virtually every major HIV medical organization worldwide. The Prevention Access Campaign (preventionaccess.org) coined the U=U phrase and maintains a list of all endorsing organizations.

Treatment

Antiretroviral Therapy (ART): Modern HIV Treatment

Antiretroviral therapy (ART) is a combination of HIV medications taken to suppress the virus. Modern ART is typically a single pill taken once daily. It does not cure HIV, but it suppresses the virus to undetectable levels, protecting the immune system and eliminating the risk of sexual transmission. Treatment should be started as soon as possible after diagnosis.

How ART Works

ART uses combinations of drugs that each target a different stage of the HIV replication cycle. Drug classes include: NRTIs (nucleoside reverse transcriptase inhibitors), NNRTIs (non-nucleoside reverse transcriptase inhibitors), integrase inhibitors, protease inhibitors, and entry inhibitors. Using combinations prevents the virus from developing resistance to any single drug. The most common modern regimens are integrase inhibitor-based and are very well-tolerated.

Long-Acting Injectable ART (Cabenuva)

Approved in 2021, Cabenuva (cabotegravir + rilpivirine) is the first complete long-acting HIV treatment given by injection once every 2 months. Like daily pills, it suppresses HIV to undetectable levels. It is a major advance for people who find daily pill adherence challenging. A monthly injectable is also available in some settings. The injections are given by a healthcare provider at a clinic.

Monitoring: Viral Load and CD4 Count

Once on ART, your provider will monitor two key numbers. Your viral load measures how much HIV is in your blood: the goal is undetectable. Your CD4 count measures immune system strength: normal is 500 to 1,500 cells/mm3. With consistent treatment, viral load typically becomes undetectable within 3 to 6 months, and CD4 count gradually recovers over months to years. These labs are typically done every 3 to 6 months initially, then annually once stable.

Adherence Is Everything

ART only works when taken consistently. Missing doses allows HIV to replicate, which can lead to drug resistance, a rising viral load, and reduced treatment options. Studies show that taking ART at least 95% of the time (missing no more than about 1 dose per month) is needed to maintain viral suppression. Taking medication at the same time every day helps build consistency. Talk to your provider about strategies if adherence is challenging, including switching to long-acting injectables.

Emergency Prevention

PEP: What to Do After a Potential HIV Exposure

Post-exposure prophylaxis (PEP) is emergency HIV medication that can prevent infection after a recent potential exposure. PEP is not a substitute for regular PrEP if you are frequently at risk, but it can be life-saving in an emergency situation.

Act Immediately: Time Is Critical

PEP must be started within 72 hours (3 days) of a potential HIV exposure. The sooner you start, the more effective it is. After 72 hours, PEP is no longer considered effective. Do not wait to see if symptoms develop.
Go to an Emergency Room, Urgent Care, or Sexual Health Clinic

Tell them you may have been exposed to HIV and need PEP. Any emergency room is required to have PEP. If cost is a concern, do not let that stop you: financial assistance programs exist. The healthcare provider will assess the exposure, test you for HIV (you must be HIV-negative to start PEP), and prescribe a 28-day course of antiretroviral medication.
Take the Full 28-Day Course

PEP must be taken every day for 28 days to be effective. Missing doses significantly reduces effectiveness. Side effects (nausea, fatigue, headache) are common in the first week but typically improve. Finish the full course regardless.
Follow Up After PEP

You will need follow-up HIV testing 4 to 6 weeks after starting PEP, and again at 3 months. If you were exposed to HIV through a pattern of events (recurring situations), talk to your provider about transitioning to PrEP after completing PEP.

When Does PEP Apply?

Potential PEP situations include: condom broke or was not used with a partner of unknown or positive HIV status; shared needles or injection equipment with someone living with HIV; or occupational exposure (needlestick or splash with HIV-positive blood). PEP is not a morning-after pill for HIV: it requires 28 days of medication and follow-up. If you are regularly in situations where you might need PEP, PrEP is the more appropriate and effective ongoing prevention strategy.

Living with HIV

Living Well with HIV in 2024

A person who is diagnosed with HIV today in the United States, starts treatment promptly, and takes their medication as prescribed can expect to live a full and healthy life, with a near-normal life expectancy. HIV does require lifelong management, but with the right care team and support, it is a chronic, manageable condition.

Relationships and Disclosure

People living with HIV have fulfilling romantic and sexual relationships. U=U eliminates transmission risk with treatment. Disclosure to sexual partners is a personal decision shaped by law (disclosure laws vary by state), ethics, and communication. Lambda Legal's HIV Project provides legal information on disclosure laws by state.

Lambda Legal HIV Project, lambdalegal.org

Mental Health and Stigma

HIV stigma remains a significant burden. Depression and anxiety are more common in people living with HIV. Affirming mental health care and peer support from HIV-positive community members can dramatically improve wellbeing. The Positive Peers app and The Well Project (for women) are community-specific resources.

HIV.gov Mental Health Resources

Finding an HIV Specialist

While primary care doctors can manage HIV for stable patients, an infectious disease specialist or HIV-specialized provider offers the most current expertise, especially when starting treatment or managing complications. The American Academy of HIV Medicine (AAHIVM) maintains a directory of HIV-specialized providers at aahivm.org.

AAHIVM Provider Directory

Paying for HIV Treatment

Ryan White HIV/AIDS Program funds care and treatment for people who are uninsured or underinsured. Gilead and ViiV manufacturer assistance programs cover medication costs. Many states have AIDS Drug Assistance Programs (ADAPs) that provide free medication. HIV.gov/topics/paying-for-hiv-care is the official federal resource for navigating costs.

HRSA Ryan White Program; HIV.gov

Community and Peer Support

Connecting with others living with HIV reduces isolation and improves health outcomes. The NMAC (National Minority AIDS Council), Positively Aware, The Body, and GLMA (LGBTQ+ Medical Association) provide community, information, and advocacy resources. Local AIDS service organizations (ASOs) offer case management, peer support groups, and navigation services.

NMAC, Positively Aware, The Body

HIV and the Law

People living with HIV are protected under the Americans with Disabilities Act (ADA) from workplace discrimination. Many states still have HIV criminalization laws that may require disclosure to partners: these laws are often scientifically outdated and disproportionately harm Black and Brown communities. Lambda Legal and the ACLU's National Prison Project work on HIV law reform. Know your rights.

Lambda Legal; ACLU HIV Project

Disparities

HIV in the LGBTQ+ Community: Understanding Disparities

HIV does not affect everyone equally. Understanding disparities is essential for addressing them. These disparities are not caused by identity, but by structural factors: poverty, racism, discrimination, lack of healthcare access, criminalization, and minority stress.

Gay and Bisexual Men

Represent 70% of new HIV diagnoses annually in the U.S.
Black gay and bisexual men are disproportionately impacted: face both racism in healthcare and HIV stigma in community
Latino MSM also face significant disparate burden
PrEP uptake remains lower among Black and Latino MSM despite higher rates of new diagnoses
The Ending the HIV Epidemic initiative specifically targets 57 jurisdictions where most new diagnoses occur

CDC HIV Surveillance Report, 2022

Transgender Women

Trans women of color face the highest HIV rates of any demographic group
Black transgender women: approximately 44% prevalence of HIV in some studies
Latina transgender women: approximately 26% prevalence
Social factors driving disparity: housing instability, criminalization of sex work, lack of healthcare access, discrimination in employment and housing
Trans-competent, affirmative HIV care providers remain scarce in many areas

CDC, 2019; NCTE U.S. Trans Survey, 2022

The Structural Drivers of HIV Disparities

HIV disproportionately affects communities that experience overlapping structural disadvantages. Poverty limits access to testing, treatment, and PrEP. Racism in healthcare leads to worse treatment outcomes and less PrEP prescribing for Black patients. Criminalization of HIV status and of sex work creates barriers to testing and care. Housing instability disrupts treatment adherence. Minority stress from discrimination damages immune function and mental health. Ending HIV disparities requires addressing these root causes alongside biomedical tools.

HIV: Testing, Treatment,and the Truth About U=U