HIV explained: prevention, testing and treatment

What HIV is and how it spreads

HIV (human immunodeficiency virus) is a virus that attacks the immune system, the body's defence against infection. Without treatment it gradually weakens immunity over years, eventually leading to serious infections and illnesses; this advanced stage is called AIDS. HIV is passed on through certain body fluids — most commonly through unprotected sex, and also through sharing needles or from parent to baby during pregnancy, birth or breastfeeding. It is not spread by everyday contact such as hugging, sharing cups, toilet seats, coughs or sneezes. Crucially, modern treatment has transformed HIV from a life-threatening illness into a long-term manageable condition, and understanding how it spreads helps remove fear and unnecessary stigma.

Testing: quick, free and confidential

Testing is the only way to know your HIV status, and it is fast, free and confidential on the NHS. Tests are available at sexual health clinics, some GP practices, through home self-sampling and self-testing kits, and at various community services. A simple blood test or finger-prick sample can give results quickly, and modern tests are highly accurate a few weeks after any possible exposure. Regular testing is recommended for anyone at higher risk. Finding HIV early means treatment can start sooner, which protects your own health and prevents onward transmission. Everyone in the UK can access testing regardless of immigration status, and results are kept private.

Treatment and living well with HIV

HIV is treated with antiretroviral therapy — a combination of medicines, usually taken as tablets, that stop the virus multiplying. Treatment does not cure HIV, but it keeps the amount of virus in the blood extremely low and allows the immune system to recover and stay healthy. People diagnosed today and taking treatment as prescribed can expect a near-normal life expectancy. Care is provided by specialist HIV teams, with regular monitoring through blood tests. Starting treatment promptly after diagnosis is now standard. Alongside medicines, looking after general health — not smoking, staying active and attending check-ups — helps people with HIV stay well for the long term.

U=U: undetectable equals untransmittable

One of the most important advances is captured in the phrase U=U — undetectable equals untransmittable. When treatment reduces the virus to levels so low that standard tests cannot detect it, the person cannot pass HIV on to sexual partners. This is backed by large, robust scientific studies and is accepted worldwide. U=U has profound effects: it removes fear and stigma, supports normal relationships, and is a powerful reason to test and start treatment. It usually takes some months of consistent treatment to become and stay undetectable, and staying undetectable depends on taking medicines as prescribed and attending regular monitoring.

Preventing HIV: PrEP, PEP and condoms

HIV can be prevented in several ways. Condoms remain a reliable barrier against HIV and many other infections. PrEP (pre-exposure prophylaxis) is medicine taken by HIV-negative people at higher risk to prevent infection; it is highly effective when taken as advised and is available free through sexual health services in the UK. PEP (post-exposure prophylaxis) is emergency medicine that can prevent HIV if started very soon — ideally within hours and no later than around three days — after a possible exposure, available from sexual health clinics or A&E. Not sharing needles and antenatal testing and treatment to prevent parent-to-child transmission are also vital parts of prevention.