Some organizations have recently required mandatory seasonal influenza vaccination for HCWs as a professional and ethical obligation to protect their patients' health [33, 34] . However, ethical issues have been raised with mandatory vaccination because, while promoting the interests of patients and employers, it challenges HCWs' personal autonomy and freedom of choice [35, 36] . Moreover, it has been suggested that vaccination is not the only avenue of influenza prevention and there are several other important measures that healthcare organizations may take to protect both patients and HCWs [37] . Further previous studies have also suggested that not all HCWs support mandatory vaccination [38] . Until mandatory influenza vaccination for HCWs is accepted worldwide, continued efforts to improve nurses' vaccination behaviours will be required.