Doctors and nurses understand that working while they’re sick can put their patients at risk. But most do so anyway, a new survey of workers at the Children’s Hospital of Philadelphia suggests – influenced by factors as varied as concerns over who will fill in for them, worries that their patients can’t get by without them and a widespread notion that health care workers who stay home to nurse a cold or stomach bug are somehow weak or unprofessional. “There is an unspoken understanding that you probably should be on your deathbed if you are calling in sick.