physicians and nurses died during the treatment of their patients. Why do not they quit their jobs despite the lack of facilities [7] and the certainty that they will become infected or die?
Past studies have suggested the role of self-sacrifice in this regard [11, 12] . We believe that in healthcare professionals, this factor can be considered a reason for not leaving the duty not only despite the insufficient personal protective equipment but also death in the way of treatment of patients. Selfsacrificing or altruistic behavior has been introduced as part of the "stewardship theory." To date, most studies in this area have focused on the stewardship behavior of managers [13] . Opposite of this view has been seen in a recent article and also in news during COVID-19 [14, 15] . The death of the "frontline healthcare professionals" during COVID-19 needed more studies to develop the new type of "self-sacrifices" theories in crisis management.
Designating a special part of researches to studying the brain mechanism of these healthcare professionals which they sacrifice themselves can be a minor substitute to their effort in the frontline fighting COVID-19.
Conflict of interest The authors declare that they have no conflict of interest.