• A skin puncture with a contaminated sharp like a needle. This could be accidental, as in a nurse slipping and pricking themselves, or partially intentional, like when drug users share dirty needles.

• Direct contact of the contaminated fluid with the eyes, nose, or mouth. These surfaces have mucous membranes, giving pathogens an entrance to the body. To prevent this contact, many healthcare workers wear personal protective equipment (PPE) like gloves, masks, eyewear, and gowns.

• Direct contact of the contaminated fluid with a wound or broken skin. When intact, the skin is the body’s primary defense against pathogens, but when there’s a cut or any type of opening, pathogens can get in and cause an infection.

• Bites that break the skin and come into contact with blood.

• Sexual contact can spread blood-borne infections between people.

• Mother-to-fetus transmission during pregnancy and birth.