Apopular question and issue that arises every year around this time is whether an employer can force it's employee to receive flu shots/vaccinations. The answer is that employers _may_ generally require employees to receive a flu shot but there are potential law violations associated with such a practice (and with requiring employees to do anything in general). Specifically, there may be issues with some employees' religion or medical conditions that may prevent them from receiving a shot and employers run the risk of violating Title VI and the Americans with Disabilities Act Amendments Act (ADAAA) and state-equivalent employment laws.
If an employee just doesn't want to be told what to do, they may face discipline and even termination and it may not run afoul of any employment law. If an employer has a reasonable purpose for requiring the shots (e.g., a health-care provider), then take that into consideration before declining the vaccination. However, if you believe you genuinely and truly cannot have a shot, contact an employment attorney to discuss the matter.