1. Routes of Transmission and Real-Life Examples:
Sexual Contact (The primary route of transmission)
Example: During unprotected vaginal or anal intercourse, if one partner is living with HIV, the virus can enter the other partner's body through mucous membranes (such as micro-tears in the rectum, vagina, urethra, or mouth).
Key Concept: The higher the viral load, the greater the risk of transmission. For individuals living with HIV who consistently take antiretroviral medication and successfully suppress the virus, the risk of transmitting HIV through sex is extremely low. This concept is known as "U=U" (Undetectable = Untransmittable), a crucial scientific fact in modern prevention and destigmatisation efforts.
2. Blood Transmission
Examples:
Sharing Needles: Sharing contaminated syringes, needles, or other injecting equipment for drug use.
Unsafe Medical Procedures: Receiving injections, blood transfusions, or organ transplants where standard infection control protocols are inadequate (this is now extremely rare in Hong Kong as all blood products are rigorously screened).
Sharing Personal Items: Sharing razors or toothbrushes that might be contaminated with blood. Although the risk is lower, it should still be avoided.
3. Mother-to-Child Transmission (Vertical Transmission)
Example: An HIV-positive mother who does not receive any preventive medical intervention during pregnancy, delivery, or through breastfeeding has a 15-45% chance of transmitting the virus to her baby.
Key Preventive Measures: Through antenatal HIV testing, the administration of antiretroviral drugs to both mother and baby, and the avoidance of breastfeeding, the transmission risk can be significantly reduced to below 1%.
