Per internal event report: Pt received 1st dose COVID vaccine Pfizer on 1/4/21. Pt returned to clinic to receive 2nd dose of Pfizer, but was given Moderna instead. Pt noticed while waiting in waiting area after vaccine administered, and notified clinic staff. State department of health was notified, and recommendation was to not further vaccinate (i.e. no 3rd dose warranted).   Per email with follow up information:   Reviewed with pt and with RN that administered the vaccine.  Check in staff did not have memory of the event.    Patient recollection of events: Pt reported that she was asked about if it was her first or second dose and confirmed it was her second dose and had her CDC card with her.  She was here for her second Pfizer.   During check in the pt stated that she was given a card for room 7 and the card was blue (Moderna). Pt stated that she had a conversation with the administering RN about it being her second dose and stated she was to have Pfizer.  She does not recall is she had her card out in the administration bay.   Pt stated she received the vaccine and was in the waiting area when she received the text from the state thanking her for getting her Moderna vaccine.  At this point she approached registration and informed them of the issue.  She spoke with Dr. X, who was volunteering in the clinic at the time.  Pt was told that she did not need to receive another shot at that time (this has been confirmed with the state).   Reviewed with the pt that she would not need to get another shot and that we would be reporting the issue.  She was appreciative of the call and understood to let me know if she had any other questions or concerns   RNs recollection of events: RN recalls giving the vaccine but does not recall verifying the card (CDC) or in Zotec about the brand of the second dose.  She recalls that the pt had the blue (Moderna) card for the room.  She was on the Moderna hallway at the time of the admin.    Process review: Typically, when we are administering 2 different vaccines, the clinic is evenly divided, with one row being Moderna (blue) and with the other row being Pfizer (red).  On 1/25/21, due to high volume of Pfizer second doses, we opened rooms in our Moderna row for Pfizer vaccine.  These rooms have red cards placed in them to match the red room number cards and the red flags on the vaccine.  The remaining Moderna rooms had blue cards to match the blue room numbers and blue flags on the Moderna Vaccine. Vaccine administration staff only give one brand of vaccine at a time.  Room 7 was one of the rooms that had been converted earlier in the day.  At the time of the admin, the room was being operated as a Moderna room.    Gaps: -At check in when the pt was given a Moderna colored card and placed in a Moderna room.  The check in person likely still thought room 7 was a Pfizer room and did not recognize the wrong colored card.   -In the admin room, the administrator did not validate the prior vaccine, or did not recognize that the vaccine was not the same as what she was administering.    Actions: -Follow up completed with administering RN on verifying prior dose, both using the CDC card and in the Zotec system.   -Reviewed process for assigning room based on type of vaccine with admin staff and clinic leads to review daily with volunteer staff.   -Pt was called and updated and informed to call if any issues or questions.