U.S. hospitals are struggling to get the workers they need to treat patients through the winter’s COVID-19 surge as the virus collides with a historically tight labor market.

High demand for labor throughout the economy is making it harder to find replacements for doctors, nurses and support staff who have been sidelined by the omicron variant. It’s especially tough in small towns and rural areas with aging populations and fewer people entering the workforce.

Finding sufficient staff is a daily challenge that industry veterans say is harder than any time they can remember. Job openings in health care and social assistance are more than double their pandemic lows, and a record number of people are quitting.