Merck is launching a chronic hepatitis C awareness campaign featuring rocker and hepatitis C sufferer Gregg Allman, whose Allman Brothers Band will headline a benefit concert on World Hepatitis Day on July 27, in New York.

Allman underwent a liver transplant a year ago because of chronic hepatitis C and said in a statement: “I want to tell [sufferers], don’t wait. Doing nothing is not an option. They need to talk with their doctor.”

Three million Americans have the disease, which can damage the liver over time and lead to cirrhosis, end-stage liver disease and liver cancer. As many as four-fifths of those infected don’t know they have the virus, said Merck.

The campaign, dubbed Tune In to Hep C, is being co-sponsored by the American Liver Foundation, whose acting CEO Newton Guerin said: “Gregg’s willingness to share his story will open the door for meaningful dialogue that can help reduce stigma and the lack of understanding surrounding chronic hepatitis C. 

Merck’s Victrelis, the first in a new class of hepatitis C drugs, won FDA approval in May, followed weeks later by rival Incivek, from Vertex.