Immunizations are complete or immunizations are completed
A more technical answer compared the top-level comment:
X is complete suggests more that something is entire and every object is included. See "My list is complete," meaning that everything I want on my list is actually on the list.
X is completed suggests that a task has be executed to "completion," à la, "I completed the job."
However, these are entirely pedantic definitions. You often hear/see people say "The job is complete." even though they mean the job has been finished.