Yesterday was World Aids Day - a chance for people to unite in the fight against the HIV, show their support for people living with it, and to commemorate people who have died from it.

In the United States, injection drug use is responsible for 9% of all new HIV diagnoses.

That's a sizable drop from the early 90s, when diagnoses among drug users peaked.

The US Center for Disease Control say needle exchanges have played a role in that huge drop.