Patient received a Pfizer-brand COVID-19 mRNA vaccine as dose #1 of his primary series on 01/18/2022 (Lot# FH8030). On behalf of the above named healthcare entity, a community-based vaccination clinic was held at the patient's place of employment (contact information included on Continuation Page.) Patient was clinically screened and found to meet all inclusion criteria for a second primary-series dose. No exclusion criteria were identified. Patient did not have his vaccination card on his person and I offered to electronically retrieve his vaccination information from the Immunization Registry. I performed a statewide search of his demographic information. His father's (whose legal name is identical to this patient's) vaccination data was inadvertently retrieved from the state's vaccination system which showed that this patient had received a Moderna mRNA vaccine. Operating under this assumption, Moderna was given to this patient. During our discussion after vaccination, I counseled the patient concerning what to expect from the second dose and which steps he could take to ameliorate any mild-to-moderate, self-limiting side effects and offered our contact information to f/u with any additional questions or concerns. The patient was monitored 15 minutes post-dose with no adverse events noted. During this time, I asked the patient if he had any additional questions about the Moderna vaccine or wanted to receive any additional information about SARS-CoV-2, which he declined. He then stated that he believed he had received the Pfizer-brand vaccine as his initial primary-series dose. Patient then retrieved his vaccination card from another area in his workplace, upon my inspection of the patient's card, this information was confirmed. I then performed another query of the Immunization Registry which revealed three individuals with the name of - all of which are related to this patient, one being his father and the other his son. Upon inspecting this patient's record, it was discovered that he had actually received the Pfizer vaccine and not Moderna.   I discussed this situation with the patient and offered my sincerest apologies. I reviewed the process and discussed how the incident occurred with the patient. I reassured him that although this is not the predominant practice for primary series COVID-19 vaccinations, I did not anticipate any adverse events or physical harm as the CDC has approved the routine administration of either mRNA vaccine type for booster doses. I also explained that in exceptional circumstances, the CDC has permitted mixed-type mRNA primary series vaccination doses in circumstances where one product may be unavailable or the administering provider and patient are unable to ascertain the initial dose given. However, since this event arose from inadvertent and not intentional circumstances, I also explained that I would be required to file a VAERS incident report. My contact information was provided to this patient and he was encouraged to follow-up with me in the event he had any additional questions, concerns, or updates regarding this event. As of the time of the filing of this report, I have not received any further contact from the patient and have not been made aware of any adverse events arising from this incident.  Thank you, PharmD