These are important facts about HIV and how it is acquired, transmitted, prevented, and treated.

WHAT ARE HIV AND AIDS?

Human immunodeficiency virus (HIV) is a virus that attacks the immune system by damaging CD4 cells, these are important cells that help defend the body against infections. The loss of these cells weakens the immune system, making it harder for the body to fight infections, illnesses and certain cancers. HIV is a lifelong condition.[1]

There are two types of HIV: HIV-1 and HIV-2. HIV-1 is the more common type, while HIV-2 is less severe and less likely to be transmitted.[1,2]

According to the World Health Organisation (WHO), there were approximately 40 million people living with HIV globally at the end of 2023.[3]

HIV is not the same as AIDS

Acquired immunodeficiency syndrome (AIDS) is the most advanced stage of HIV.[4,5] It occurs when the immune system becomes severely damaged, making the body vulnerable to life-threatening opportunistic infections —these are infections that occur more frequently or are more severe in individuals with weakened immune systems. AIDS can also make people more vulnerable to certain types of cancers.[4,6,7]

Living with HIV does not mean you will develop AIDS.[4] Due to effective treatment options, most people living with HIV do not develop AIDS.[4] However, if left untreated, HIV will usually progress to AIDS within about 10 years, though this timeline can vary.[6] If AIDS is then left untreated, life expectancy is 2 years but with effective treatment people with AIDS can live longer than 10 years or even have a normal life expectancy.[6,8]

WHAT ARE THE SYMPTOMS OF HIV?

The symptoms of HIV vary from person to person and depend on the stage of the virus. There are several stages of HIV — acute HIV infection, chronic HIV infection and AIDS.[9]

During the acute stage, which is within the first 2–4 weeks of acquiring HIV, some people may experience flu-like symptoms such as:[1,9]

Fever

Muscle aches

Sore throat 

Diarrhoea

Fatigue

Rash

Swollen lymph nodes

In this acute stage, HIV is most easily transmitted because the virus is multiplying rapidly, however, some people may not experience any symptoms during these early stages.[9,10]

During the chronic stage of HIV, which can last 10–15 years without treatment, the virus continues to slowly multiply.[9] Individuals may not feel ill or show any symptoms during this period, however, HIV can still be transmitted to others.[1,9]

If HIV progresses to AIDS, symptoms can include:[9]

Rapid weight loss

Prolonged diarrhoea

Pneumonia

Extreme tiredness

Mouth, anus, or genital sores

Memory loss or other neurologic disorders

In the AIDS stage, many symptoms arise from opportunistic infections (infections that occur more frequently or are more severe in individuals with weakened immune systems), cancers, or other illnesses known as AIDS-defining conditions.

These include:[1,9]

Tuberculosis (TB)

Candidiasis of the digestive tract

Non Hodgkin's Lymphoma

HIV encephalitis and HIV-associated neurocognitive disorder (HAND)

Mycobacterial infections

Kaposi's sarcoma

HIV wasting syndrome

It’s important to remember - experiencing symptoms associated with any of the three stages of HIV does not necessarily mean a person has HIV, as these symptoms can also be caused by other illnesses. The only way to confirm HIV is through testing.[9]

HOW IS HIV TRANSMITTED?

HIV is transmitted when certain body fluids—such as blood, semen, pre-seminal fluid, anal fluids, vaginal fluids, and breast milk—enter the bloodstream.[1,11] This can occur through mucous membranes, which are wet and absorbent areas of the body, such as those in the anus, penis, vagina, and mouth. Transmission can also happen through open cuts, sores, or direct injection.[11]

The most common ways HIV is transmitted include:[1,12]

  • Unprotected anal or vaginal penetrative sex.
  • Sharing needles or other injection drug equipment.
  • Mother-to-child transmission (MTCT) during pregnancy, childbirth, or breastfeeding.

Having a sexually transmitted infection (STI) can also increase the likelihood of acquiring or transmitting HIV as an STI can cause a sore or a break in the skin, making it easier for the HIV virus to enter the body.[13]

Although extremely rare, HIV can also be transmitted through oral sex. Additionally, while it is possible to acquire HIV through blood transfusions, the likelihood is extremely low due to the rigorous screening processes applied to all donated blood before use.[11,12]

People living with HIV who achieve an undetectable viral load through effective treatment cannot transmit the virus through sexual contact, a principle known as 'Undetectable = Untransmittable' (U=U).[11] However, U=U applies only to sexual transmission. While having an undetectable viral load significantly reduces the risk of transmission through other means, it does not eliminate it entirely.[14–16]

HIV cannot be spread through everyday social contact

There are various ways in which HIV cannot be transmitted, including:[11,12,17]

  • Contact with saliva, sweat, or tears that is not mixed with blood
  • Shaking hands
  • Hugging
  • Using the same toilet
  • Insect bites
  • Swimming in the same pool
  • Sharing food utensils

Additionally, HIV is not airborne and cannot survive for very long outside the body, therefore, contact with blood or semen that is outside of the body and exposed to the environment does not usually pose a risk of HIV transmission.[17]

HOW IS HIV PREVENTED?

There is currently no HIV vaccine available, but it is possible to prevent or greatly reduce the likelihood of acquiring HIV through various prevention strategies, these include:[18-20]

Always using condoms during sex.

Both partners getting tested for HIV before sex.

Never sharing needles or other drug injection equipment.

Additionally, pre-exposure prophylaxis (PrEP) can be taken before potential exposure to HIV to prevent infection, and post-exposure prophylaxis (PEP) can be taken within 72 hours after possible exposure.[4,19]

For people living with HIV, taking their HIV medication as prescribed to achieve and maintain an undetectable viral load is a key way to further prevent HIV transmission through sexual activity.[4,19]

With these effective prevention strategies, people living with HIV can have HIV-negative sexual partners without transmitting the virus.[4,14]

Partners living with HIV also need to practice safe sex

Additionally, sexual partners who are both living with HIV still need to use condoms to prevent HIV superinfection. This occurs when a person already living with HIV acquires a different strain (form) of HIV. Some strains of HIV are drug-resistant, which means HIV medications are not effective in treating that strain. Some strains of HIV are also more severe and may lead to progression of the virus.[21,22]

People living with HIV can get pregnant

It is possible for people living with HIV to get pregnant and give birth to HIV-negative babies through effective mother-to-child transmission (MTCT) prevention strategies. These include:[23]

  • Being on HIV treatment during pregnancy.
  • Choosing caesarean section instead of vaginal delivery.
  • Feeding the baby with formula milk instead of breastfeeding.
  • Giving the newborn infant PEP.

A pregnant person living with HIV may face some challenges, so it’s important to maintain close contact with a doctor during this time.[23]

HOW TO TEST FOR HIV

The only way to know if you have HIV is by getting tested because symptoms don’t always occur.[4,9] Everyone should get tested at least once in their life, however, people who are more likely to acquire HIV should undergo testing more often, these include:[24-25]

  • People who have sexual partners living with HIV.
  • People who have sexual partners and do not know their HIV status.
  • People who inject drugs.
  • People who exchange sex for money or drugs.

There are three different types of HIV tests:

  • antibody tests,
  • antigen/antibody tests, and
  • nucleic acid tests (NATs)

These tests differ in how quickly they can detect HIV, depending on the window period, which is the time between when a person acquires HIV and when the test can accurately detect HIV.[1,24,25] Among these tests, nucleic acid tests are the fastest at detecting HIV.[25] 

A negative test result means no HIV was detected, but a positive result means HIV is present.[26] Following a positive result, treatment should start as soon as possible.[4] With a negative result, you might need another test to confirm your HIV status if the test was done within the window period.[24] 

While HIV tests can detect HIV, they cannot tell how long it has been since HIV acquisition.[25]

HOW IS HIV TREATED?

There is no cure for HIV, but there are highly effective treatments called antiretroviral medications (ARVs).[1] Antiretroviral therapy (ART) is a combination of different ARVs that prevent HIV from multiplying and spreading in the body. By reducing the amount of HIV, known as the viral load, ART helps achieve viral suppression, allowing the immune system to repair and strengthen itself.[1,4,27]

ART can reduce the viral load to levels so low that it cannot be detected by standard HIV tests, this is known as an undetectable viral load, and follows the (U=U) principle.[11] This means the virus can no longer be transmitted through sexual contact and significantly reduces the risk of transmission through other means.[27] Most people will be able to achieve an undetectable viral load within 6 months of starting ART.[11]

ART has transformed HIV into a chronic, manageable condition. With this treatment, HIV now rarely progresses to AIDS, allowing people living with HIV to lead long, healthy lives and achieve a normal lifespan.[1,4] ART is recommended for everyone living with HIV, including pregnant and breastfeeding women, and should begin as soon as possible after a positive HIV diagnosis.[4,27]

There are two ways to take ART:

  • Oral daily pills

  • Long-acting injections[27]

ART is a lifelong treatment, and it is important to take ART exactly as prescribed to maintain viral suppression and also prevent drug resistance.[1,5] Developing drug resistance can cause treatments to stop being effective.[28]

Some ART can have side effects.[1] Most of them are short-term and improve within a few weeks such as nausea, sleep problems and fatigue, however, some can have longer-term effects such as bone, liver, or kidney problems and heart disease.[1,29]

Abbreviations:

AIDS, acquired immunodeficiency syndrome; ART, antiretroviral therapy; ARV, antiretroviral; HIV, human immunodeficiency virus; MTCT, mother-to-child transmission; NAT,  nucleic acid test; PEP, post-exposure prophylaxis; PrEP, pre-exposure prophylaxis; STI, sexually transmitted infection.

References:

  1. NIH. Justiz Vaillant AA, Gulick PG. HIV and AIDS Syndrome. 2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534860/#article-22914.s9 [Accessed: January 2025]
  2. National HIV Curriculum. Spach HD, Budak ZJ. Core Concepts - HIV-2 Infection. 2025. Available from: https://www.hiv.uw.edu/go/key-populations/hiv-2/core-concept/all [Accessed: January 2025]
  3. World Health Organization. HIV data and statistics. Available from: https://www.who.int/teams/global-hiv-hepatitis-and-stis-programmes/hiv/strategic-information/hiv-data-and-statistics [Accessed: January 2025]
  4. HIV.gov. What are HIV and AIDS? 2023. Available from: https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/what-are-hiv-and-aids [Accessed: January 2025]
  5. World Health Organization. HIV and AIDS. 2024. Available from: https://www.who.int/news-room/fact-sheets/detail/hiv-aids [Accessed: January 2025]
  6. NIH. Waymack JR, Sundareshan V. Acquired immune deficiency syndrome (AIDS). 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537293/ [Accessed: January 2025]
  7. NIH. What is an Opportunistic Infection? 2021. Available from: https://hivinfo.nih.gov/understanding-hiv/fact-sheets/what-opportunistic-infection [Accessed: January 2025]
  8. Poorolajal J, Hooshmand E, Mahjub H, et al. Survival rate of AIDS disease and mortality in HIV-infected patients: a meta-analysis. Public health. 2016;139:3-12. doi:https://doi.org/10.1016/j.puhe.2016.05.004
  9. HIV.gov. Symptoms of HIV. Available from: https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/symptoms-of-hiv [Accessed: January 2025]
  10. AIDSMAP. Pebody R. The stages of HIV infection. 2020. Available from: https://www.aidsmap.com/about-hiv/stages-hiv-infection [Accessed: January 2025]
  11. HIV.gov. Viral Suppression and an Undetectable Viral Load. 2025. Available from: https://www.hiv.gov/hiv-basics/staying-in-hiv-care/hiv-treatment/viral-suppression [Accessed :March 2025]
  12. NIH. How is HIV transmitted? 2021. Available from: https://www.nichd.nih.gov/health/topics/hiv/conditioninfo/transmission [Accessed: January 2025]
  13. NIH. HIV and Sexually Transmitted Diseases (STDs). 2021. Available from: https://hivinfo.nih.gov/understanding-hiv/fact-sheets/hiv-and-sexually-transmitted-diseases-stds [Accessed: January 2025]
  14. AIDSMAP. Stanford A. Undetectable viral load and HIV transmission. 2023. Available from: https://www.aidsmap.com/about-hiv/undetectable-viral-load-and-hiv-transmission [Accessed: January 2025]
  15. Terrence Higgins Trust. Difficult questions about U=U. Available from: https://www.tht.org.uk/about-us/what-we-do/training/cant-pass-it-training/difficult-questions-about-uu [Accessed: January 2025]
  16. AIDSMAP. Pebody R. Despite reassuring data, we can’t yet say U=U for breastfeeding. 2017. Available from: https://www.aidsmap.com/news/nov-2017/despite-reassuring-data-we-cant-yet-say-uu-breastfeeding [Accessed: January 2025]
  17. Terrence Higgins Trust. How HIV is transmitted. 2024. Available from: https://www.tht.org.uk/hiv/about-hiv/how-hiv-transmitted [Accessed: January 2025]
  18. HIV.gov. HIV Vaccines. 2024. Available from: https://www.hiv.gov/hiv-basics/hiv-prevention/potential-future-options/hiv-vaccines [Accessed: January 2025]
  19. NIH. The Basics of HIV Prevention. 2023. Available from: https://hivinfo.nih.gov/understanding-hiv/fact-sheets/basics-hiv-prevention [Accessed: January 2025]
  20. CDC. About HIV. 2025. Available from: https://www.cdc.gov/hiv/about/index.html [Accessed: January 2025]
  21. Office on Women’s Health. OASH. Facts about HIV and AIDS. 2025. Available from: https://womenshealth.gov/hiv-and-aids/hiv-and-aids-basics/facts-about-hiv-and-aids [Accessed: January 2025]
  22. Móréh Á, Szilágyi A, Scheuring I, et al. Variable Effect of HIV Superinfection on Clinical Status: Insights From Mathematical Modeling. Frontiers in Microbiology. 2018;9. doi:https://doi.org/10.3389/fmicb.2018.01634
  23. Terrence Higgins Trust. Preventing transmission during pregnancy, birth and breastfeeding. 2024. Available from: https://www.tht.org.uk/hiv/living-well-hiv/parenthood/preventing-vertical-transmission [Accessed: January 2025]
  24. NIH. Huynh K, Kahwaji CI. HIV Testing. 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482145/ [Accessed: January 2025]
  25. NIH. HIV Testing. 2024. Available from: https://hivinfo.nih.gov/understanding-hiv/fact-sheets/hiv-testing [Accessed: January 2025]
  26. NHS. Diagnosis - HIV and AIDS. 2021. Available from: https://www.nhs.uk/conditions/hiv-and-aids/diagnosis [Accessed: January 2025]
  27. NIH. HIV Treatment: The Basics. 2025. Available from: https://hivinfo.nih.gov/understanding-hiv/fact-sheets/hiv-treatment-basics [Accessed: January 2025]
  28. WHO. HIV Drug Resistance. 2024. Available from: https://www.who.int/news-room/fact-sheets/detail/hiv-drug-resistance. [Accessed: January 2025]
  29. AIDSMAP. Jones A. Side-effects of HIV treatment. 2018. Available from: https://www.aidsmap.com/about-hiv/side-effects-hiv-treatment [Accessed: January 2025]

NP-GBL-HVX-COCO-250017 October 2025

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist, or nurse. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the GSK Reporting Tool link https://gsk.public.reportum.com/. By reporting side effects, you can help provide more information on the safety of this medicine.

If you are from outside the UK, you can report adverse events to GSK/ ViiV by selecting your region and market, here.