That is aggravating. I'm sorry you keep getting sick. Having the flu 5 times in a year would be highly unusual though. Having it more than once would be unusual. We develop antibodies to each flu each season. There are a couple of different strains but most people don't get multiple flus. Never say never though, I guess. But colds, illnesses and bugs are definitely highly contagious. And if you are in an environment that is new, those are new germs. I swear, my kids were always the most sick when they started at a new school. For the first year there, they'd be fighting off everything. Then it got better as the years went on in that same environment because they'd probably been exposed to enough germs to build up immunity. Any time you are around people and lots of them, you expose yourself to germs. Good hand hygiene helps like washing or hand sainting frequently and when I worked in an office, I brought in some sanitizing cleaning wipes and cleaned down my whole area. A little anal attentive but I figured I might as well start off germ free. Then I did it once a week or more if I shared a computer with someone or something like that and our hands would touch the same things. I also think we can get run down when we are working. Less sleep, less self care , not eating as well, etc. That all lowers our immunity. The other possibility is that your building you work in has mold or something like that. Is the location a common thread to getting sick more frequently?