DES MOINES, Iowa (AP) — A surge in coronavirus cases in Iowa has significantly stressed medical centers as people rush to get tested, hospitalizations surge and health care workers are sidelined by illness.

University of Iowa Health Care CEO Suresh Gunasekaran said Thursday that Iowa is likely entering a peak of virus activity with the highly transmissible omicron variant, and the next three to four weeks will be critical in determining the severity and length of the virus surge.

Demand for testing at hospitals and clinics is at an all-time high, and among those infected are many health care workers or their families.

Gunasekaran said that has led to staff shortages that have strained hospital resources more now that at any time during the pandemic.