From what I understand, each year, they take a guess at which strain it will be and only give the vaccine for that particular one. If it’s the wrong one, then it offers no protection. While working at JHU, we got free shots. I did it for 3 years, but haven’t done it for the last 3. I haven’t had the flu since long before I started working there. Personally, I don’t really think you need them, but as Coda mentioned, I understand why some people get them. Avoiding sick people and eating healthy will go a long way to providing the same precautions as the shot, IMO.