Some of our patients believe that they have had reactions to influenza vaccine in the past and request the dose to be split into 2 doses administered on different days. Is this an acceptable practice?

This is not an acceptable practice. Doses of influenza vaccine (or any other vaccine) should never be split into “half doses.” If a “half dose” is administered, it should not be accepted as a valid dose. The second half of the dose may be administered if the error is caught and corrected at that visit; if not, repeat the vaccination as soon as possible with a full age-appropriate dose.