HIV/AIDS

U=U means that a person living with HIV who is on antiretroviral therapy and has maintained an undetectable viral load for at least six months cannot sexually transmit HIV to their partners. This is not a probability reduction, it means zero transmissions. The evidence comes from three large multinational clinical trials: PARTNER (2016), PARTNER2 (2019), and Opposites Attract: together tracking over 75,000 condomless sex acts between HIV-serodiscordant couples where the HIV-positive partner was on ART with undetectable viral load. Transmissions: zero. U=U is endorsed by the CDC, WHO, and major HIV medical associations worldwide. It fundamentally changed what it means to live with and love someone with HIV.

Yes, but the risk is extremely low, so low that most transmission probability tables list it as 'negligible' or present it as near-zero. The risk is highest for the person performing oral sex on a penis (fellatio) when the partner has HIV. Performing oral sex on a vulva (cunnilingus) or receiving oral sex are even lower risk. Factors that could marginally increase risk include active sores or inflammation in the mouth, bleeding gums, a high viral load in the HIV-positive partner, or an active STI. Condoms and dental dams eliminate the transmission risk. For most people in most contexts, oral sex is not a meaningful HIV transmission route, but it's not zero.

PrEP (pre-exposure prophylaxis) is HIV prevention medication taken by HIV-negative people who are at risk of acquiring HIV. The daily oral option, Truvada or Descovy (both tenofovir-based), reduces the risk of sexually acquired HIV by more than 99% when taken consistently. A bimonthly injectable option (Apretude, long-acting cabotegravir) is equally or more effective and suits people who'd rather visit a clinic every two months than take a daily pill. PrEP is recommended for: MSM with recent partners of unknown status, people with HIV-positive partners not confirmed undetectable, people who have had a recent STI or use condoms inconsistently, and people who inject drugs. PrEP requires an HIV test before starting and follow-up every three months. With ACA insurance or manufacturer programs, it's often $0. PrEP is one of the most effective public health interventions ever developed.

PEP (post-exposure prophylaxis) is a 28-day course of antiretroviral medication taken after a potential HIV exposure to prevent the virus from establishing infection. It must be started within 72 hours of exposure: and the sooner the better, ideally within hours. PEP is for discrete exposures: a condom breaking with a partner of unknown HIV status, sharing injection equipment, sexual assault, or a medical needlestick. Go immediately to an emergency department, urgent care, or HIV clinic, do not wait to see if symptoms develop or for the clinic to open the next morning. PEP is about 80% effective when started promptly and taken consistently for the full 28 days. It is not a substitute for PrEP if you have ongoing risk; talk to a clinician about transitioning from PEP to PrEP after completing the course.

Without treatment, the median time from HIV infection to AIDS is approximately 10 years, though this varies significantly. A small percentage of people (called 'long-term non-progressors' or 'elite controllers') maintain CD4 counts without significant decline for many years without treatment. At the other end, some people progress to AIDS faster, particularly if infected with a more virulent strain or if they have other health conditions. AIDS is defined as a CD4 count below 200 cells/µL or the diagnosis of an AIDS-defining illness. With ART started early, this progression essentially never happens, people on effective treatment maintain their CD4 counts indefinitely and never develop AIDS.

Yes: for most people diagnosed with HIV today and started on treatment, the answer is an unequivocal yes. Modern antiretroviral therapy is one pill once a day with a side-effect profile vastly better than earlier regimens. People who start ART early and maintain viral suppression can expect a lifespan approaching that of HIV-negative peers, with essentially the same quality of life. The most important predictor of long-term health is how early ART is started, which is why testing matters. People with HIV live, travel, exercise, have children, and maintain relationships like anyone else. The persistent stigma surrounding HIV does not reflect the medical reality of 2026.

HIV can be transmitted from a pregnant person to their baby during pregnancy, labor, delivery, or breastfeeding: but with modern ART, this risk drops below 1%. Every pregnant person should be tested for HIV at the first prenatal visit (and again in the third trimester in higher-prevalence settings). If you are HIV-positive, you should be on ART throughout your pregnancy; the medication is safe in pregnancy and the benefit to the baby far outweighs any risk. Infants receive a short course of antiretroviral medication after birth as additional protection. A cesarean delivery is recommended if viral load is above 1,000 copies/mL near delivery. In the US, formula feeding is generally recommended to eliminate the breastfeeding transmission route, though guidelines differ in resource-limited settings. A parent with HIV can have a healthy baby.

Not yet for the general population. HIV establishes latent reservoirs in long-lived immune cells that current antiretrovirals cannot reach. A handful of patients have been 'cured' of HIV through stem-cell transplants from donors with the CCR5-delta32 mutation (which makes cells resistant to HIV entry), but this procedure is high-risk, complex, and not applicable as a broad strategy. Research into a functional cure, one that allows the immune system to control HIV without lifelong ART, is active and has shown promising early results in animal models and a few human cases. A vaccine against HIV has also proven exceptionally difficult to develop due to the virus's rapid mutation rate and immune evasion strategies. For now, ART is lifelong, but it is effective, tolerable, and provides a near-normal life.

The legal answer varies by state: some US states have criminal laws that require disclosure of HIV-positive status to sexual partners, with criminal penalties for non-disclosure even without transmission. These laws vary widely in their scope, and many were written before U=U was established, some criminalize activities where transmission is scientifically impossible if the person is undetectable. Know the law in your state. The ethical answer is more nuanced and personal; talking to an HIV-knowledgeable clinician, legal advocate, or support organization can help you navigate this. The practical reality for many people is that U=U and starting a conversation about prevention tools (PrEP, condoms) allows partners to make informed decisions without necessarily centering the diagnosis itself.

Acute HIV infection is the 2–4 week period immediately after exposure when the virus replicates explosively throughout the body. The viral load peaks at millions of copies per milliliter, making this the single most infectious period of the entire infection. Many people experience flu-like symptoms: high fever, swollen lymph nodes, severe fatigue, rash, sore throat, and muscle aches. Because antibody-based tests (including rapid tests and self-tests) are negative during this phase, the only test that can detect acute HIV is an HIV RNA (NAT) test. Acute HIV matters because untested, unaware people transmit a disproportionate share of new HIV infections during this window. If you have these symptoms 2–4 weeks after a potential exposure, seek testing with an RNA test specifically, and tell the clinician about the timeline.