I would add that for those of us who have a weakened immune system or are taking immune suppressants due to autoimmune disease that it's equally important for us to encourage those around us (people you live and work with) to also take measures to lessen their chances of getting the flu so that we don't catch it from them. For some households that may mean everyone getting flu shots. For others it may mean lots of handwashing and many of the strategies that Joanna lists above. In my house it's both. At my workplace I've made it clear to those I work closely with that I have a weakened immune system and I need them to be very mindful about being near me if they are not feeling well. Sometimes that means I ask that we do phone call meetings even when we are both in the office. Not always an easy conversation but one I force myself to be assertive about.