HIV: The Facts

HIV is a virus which weakens the human immune system. HIV stands for human immunodeficiency virus. The immune system is the body’s natural defence that protects it against disease and ill health. If HIV is left undiagnosed and untreated HIV can cause damage to the immune system which can leave people vulnerable to other infections. HIV is not the same as AIDS.

AIDS stands for acquired immune deficiency syndrome, it is what happens to someone who has HIV which is left untreated. Today, doctors and nurses are more likely to use terms like 'advanced HIV' or 'late-stage HIV' than AIDS. Early diagnosis and treatment is the key to avoiding becoming ill which can eventually lead to advanced HIV, when the immune system is overwhelmed and unable to fight off infections. You cannot catch AIDS and there is no such thing as an 'AIDS test'.

U=U stands for Undetectable Equals Untransmittable! U=U is a global campaign message to help people understand that a person living with HIV who is on effective treatment has zero risk of transmitting HIV during sex. HIV treatment effectively reduces the amount of the virus in the body to the point where it cannot be detected or transmitted.

Taking HIV treatment not only protects other people during sex, but allows people living with HIV to live healthy, active lives and manage their own HIV as a long-term health condition.

During sex

HIV can be transmitted through sexual fluids including semen (including pre-cum), vaginal fluids and anal mucus. Whether HIV is transmitted during sex is dependent on a number of factors, the most important being if the person with HIV has a high viral load (e.g. a large volume of HIV in their body). The higher the viral load, the more likely HIV will be transmitted during sex. Condoms, HIV treatment and PrEP can all stop HIV transmission occurring during sex.

Sharing needles and injecting equipment

HIV is also present in blood and it is possible to transmit HIV when sharing needles and injecting equipment when taking intravenous drugs. Using new, clean needles avoids the chance of transmission.

Vertical transmission

HIV can also be passed to a child through pregnancy, during birth or breast milk. Vertical transmission is extremely uncommon in the UK, as doctors test all mums and pregnant parents for HIV, and work with pregnant women and people to reduce the risk of this happening.

CD4 count and viral load are two measures which are used to determine how HIV is impacting the body and the immune system.

CD4 count

CD4 count measures the strength of the immune system. CD4 cells are an extremely important part of our immune system, they raise the early warning when the body is under attack from infections and disease and let it know it needs to take action. HIV attacks and kills these cells which can leave the body vulnerable if it is left untreated.

HIV doctors usually test your CD4 count once or twice a year to check on the health of your immune system.

Viral load

This test tells you how much HIV is in your blood. The lower this number, the less HIV is in the body, the less damage it can cause and less likely it can be passed on, especially during sex. The aim of HIV treatment is to get the viral load to undetectable. This means that the amount of HIV in the body is at such low levels that the risk of passing on HIV is zero and people can live healthy and active lives. Most people will quickly become undetectable once they start HIV treatment.

An 'undetectable viral load' means that HIV cannot be traced in the viral load blood test taking by an HIV doctor or nurse.

Having an undetectable viral load is one of the main aims of HIV treatments and means that:

• The HIV treatment is working
• HIV is causing less damage to the body and the immune system
• The chance of passing on HIV is zero.

PEP stands for post-exposure prophylaxis. It is a combination of three HIV drugs which reduce the likelihood of a HIV negative person getting HIV after they have been exposed to the virus. PEP is available from sexual health clinics or Emergency Departments (A&E).

PEP needs to be taken as soon as possible after a potential exposure to increase its chances of working effectively. Ideally, you should start PEP within 24 hours of potential exposure to HIV, but it can be taken up to 72 hours after. The medication is taken for 28 days, and you need to take all the tablets, even if you don't feel unwell.

PEP works by attempting to stop HIV from establishing itself in the body during the initial stage of infection. 

PrEP stands for pre-exposure prophylaxis and prevents HIV from being able to take hold in the body if they are exposed to it. It works by taking HIV treatment daily, or before and after sex. A sexual health doctor will let you know how you can take PrEP based on what sex you are having, and your chances of being exposed to HIV. 

PrEP is available for free on the NHS,  and you can access PrEP by contacting your sexual health clinic.