Annie Lennox HIV PositiveAnnie Lennox performed on 'Idol Gives Back' wearing a shirt with "HIV Positive" written on it.

The singer, who is not HIV positive herself, has worn the tee before, as part of a statement about being more positive about the virus. (This photo was taken from an event this past March in London.)

In a video from last November, Lennox explained her decision to wear the shirt. "Many people are [HIV positive]. In fact, 22 million people in sub-Saharan Africa are currently HIV positive. I'm wearing this in solidarity with them because it's very hard when you are HIV positive to be open about your status," she says.

"It's hard to be able to tell your family, to tell your friends. This is an illness, if you like, that ... carries a lot of stigma with it ... and what we need to do is normalize HIV so that it can be just like any other disease," she continues. Watch the Video.