With U.S. public health experts warning of a cresting wave of coronavirus infections in the coming weeks, rates of transmission among the nation’s front-line fighters — doctors, nurses and other medical staff — are setting off alarm bells.

Disparities in testing and tracking in many states — and the lack of national data — make the actual infection rates among medical personnel difficult to pin down. Still, state health departments in Ohio and Minnesota are reporting that up to 20 percent of those infected are health care professionals, a number in line with Italy and other hard hit regions of the world.

In Ohio, the percentage of health care workers infected recently ticked up to 18 percent from 16 percent of all coronavirus cases, department spokesperson Melanie Amato told NBC News. In Minnesota, as of early this week, the Department of Health confirmed approximately 1 in 5 diagnosed cases were health workers, with the caveat that health workers probably have better access to testing.