(CNN) The novel coronavirus seems to hit health care workers harder than others who contract the disease, but it's unclear why, according to disease experts.

"We know the high mortality in older people, but for reasons that we don't understand, front-line health care workers are at great risk for serious illness despite their younger age," Dr. Peter Hotez, professor and dean of the National School of Tropical Medicine at Baylor College of Medicine , said during an appearance on CNN's New Day on Monday morning.

"There's nothing more destabilizing" than health care workers falling ill, Hotez told CNN, and he said it will take time to determine what is making them sicker than other patients.

Hotez's comments followed a weekend in which the American College of Emergency Physicians said two doctors suffering from the coronavirus were in critical condition: a physician in his 40s in the state of Washington and a 70-year-old in New Jersey.

It wasn't clear whether the Washington doctor contracted the illness through work or community spread, but he complied with all relevant protocols, ACEP said.

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