Is sexual-activity with an HIV positive person a 100% guarantee of infection to the negative person?

No, sexual activity with an HIV positive person does not guarantee infection to the negative person. However, the risk of transmission is higher if precautions are not taken, such as using condoms or pre-exposure prophylaxis (PrEP). It is important to have open and honest communication with sexual partners about HIV status and to practice safe sex to reduce the risk of transmission.