Over the Fourth of July weekend, blues stars Gregg Allman and Curtis Salgado helped bring a testing and awareness campaign for the hepatitis C virus (HCV) to Oregon’s Waterfront Blues Festival, Oregon Live reports.

Throughout the weekend festival, concert attendees received free hep C tests, as well as screening for glaucoma, blood pressure, blood glucose and hearing at a free health pavilion set up during the festivities. On-site testing for hep C was also provided right near the stages for musicians who wanted to get tested.

Unfortunately, Allman, the longtime frontman of the Allman Brothers Band, pulled out from the show at the last minute because of undisclosed health issues. Allman was diagnosed with hepatitis C in 1999 but thinks he was infected when he was 20 years old from an unsafe tattoo. The musician received a liver transplant in 2010 and has since become an outspoken advocate for bringing awareness to the disease.

Curtis Salgado, who took Allman’s place as the festival’s headliner and is also a hep C survivor, recently joined the Caring Ambassadors Program, which sponsored the free testing event. Salgado, a recovering addict, contracted the disease in 1988, underwent a successful liver transplant in 2006 and has since reclaimed his fame in the blues music scene.

Bruce Conte, guitarist for the band Tower of Power, and Tracy Pain of Soul Sisters also took part in the festival’s awareness campaign.

For more information about the testing event, click here.