For injections, the only way these would be allowed as an E&M on the same day is if they are for two different diagnoses and even that, I find, is difficult to get the second service paid.
If the RN is doing vitals only or the injection is part of the APRN service (i.e. ordered for the condition being evaluated or vaccinations in a well visit), then those should be incorporated into the APRN/MD note with the an injection administration code plus the code for the injection and would not be separately billable. In this case, due to the administration code, often a 25 modifier is required on the E&M code.
Modifier 25: Significant, Separately Identifiable Evaluation and Management Service by the Same Physician or Other Qualified Health Care Professional on the Same Day of the Procedure or Other Service
We only bill 99211 if the patient comes in on a separate day for an injection.