HIV can be transmitted in four ways:
Through unprotected penetrative sex with an infected partner
This is the most common form of transmission. Consistent and proper use of condoms is the best way to prevent the spread of HIV. Condoms are available free from Sexual Health and Family Planning Clinics, and also prevent the spread of other sexually transmitted infections.
Through contaminated blood, blood products or donor transplants
All blood, blood products and donated organs in the UK are now screened for HIV to prevent transmission and so are perfectly safe.
By sharing needles when injecting or other use of sharing contaminated injecting or skin piercing equipment
If you do inject drugs, you can protect yourself by never sharing needles or other equipment with anyone else; by always using a new needle and syringe; and by always sterilizing needles and syringes between uses.
From an infected mother to her child, in the womb, at birth, or during breast-feeding
If the mother is taking HIV medication during her pregnancy, the baby is delivered by caesarian section, the baby has a short course of HIV medication after birth and is not breast-fed, the chances of onward HIV transmission from mother to baby is less than 1%.