Baby Boomers may represent 27% of the US population, but the Centers of Disease Control says they account for 75% of hepatitis C cases and wants every single Boomer tested. The government agency issued the new guidelines Thursday, noting that they aren’t an overhaul of the old advice—anyone with a history of known risks like intravenous drug use, an HCV-infected mother, or dialysis patient should still be tested.

The new guideline, which formalizes a May CDC proposal, is a blanket measure for a few reasons. First, because the age group has “a disproportionally high prevalence of HCV infection and related disease,” and second, because the high numbers are most likely low-end estimates: The CDC notes that a recent national survey found that “55% of persons ever infected with HCV reported an exposure risk…and the remaining 45% reported no known exposure risk.”

The disease is linked to higher risk of liver disease and liver cancer, and infection rates have been soaring. The CDC says that in 1965 about 18 out of every 100,000 people were diagnosed, but that number increased by more than 620 times, to 130 out of every 100,000 in the 1980s. The agency’s most recent estimate is that 17,000 more patients were infected in 2010.

Drugmakers continue to push for screening. “Only about 10% of [HCV] patients get diagnosed and treated in the US,” inThought Research’s Dr. Ben Weintraub told MM&M earlier this year in an interview.