Some exceptions to the time-away-from-work tradition do exist. Physicians, nurses, emergency-room personnel and elected officials (and any professional whose duties cannot be taken over by others during their absence) can work during the shiva period.
This exception is made because these individuals are performing a vital service that ultimately results in the betterment of society. In the event that the absence of a mourner observing the shiva will result in extreme economic loss, an exception can also be made to allow the individual to continue his or her work. (In this instance, the individual should attempt to work at night in order to observe shiva during the day. If possible, the mourner should strive to postpone work responsibilities until after the third day of mourning.) Finally, an exception exists that allows impoverished mourners to be exempt from observing the full seven days of shiva. Destitute mourners should observe the first three days of shiva; after the first three days, the mourners can return to work.