One of staff gave an employee a 0.3 ml intramuscular by accident; JYNNEOS was administered intramuscular; Mistakenly given Jynneos instead of Covid booster; Case reference number US-BN-2022-004025 is a spontaneous case received from health care professional (nurse) on 10-Oct-2022 via agency (reference number: USBAV22-1669) and concerns *41-year-old* female patient.  The patient's relevant medical history was not provided. It was mentioned that the patient was young and healthy. The reporter also stated that he didn't think the patient was pregnant but mentioned that she was of childbearing age.  The patient's concomitant medication details were not provided.  On 10-Oct-2022, the patient was vaccinated with the first dose of Jynneos (Smallpox and Monkeypox Vaccine, Live, Nonreplicating; batch number: FDP00016) at a dose reported as 0.3 ml, intramuscularly (explicitly coded as 'inappropriate route of product administration' and 'accidental underdose'), at an unknown anatomical site. The administration happened at vaccine clinic for staff. It was stated that administration was done by one of the staff to an employee and that it was done that way by an accident. It was also stated that COVID booster was meant to be given (explicitly coded as 'wrong product administered'). The staff was wondering if there were any concerns around receiving Jynneos via inappropriate route of administration and was concerned about spacing for the COVID booster.  *At the time of this report, the patient did not experience any adverse event due to Jynneos.*   The case is linked to the case US-BN-2022-004026 (same reporter).  Additional information received from Bavarian Nordic on 17-Oct-2022 included the local BN case ID.  All follow-up information is blended into the case narrative above, with the latest information pre-sented between asterisks (*).  Follow-up information received on 27-Oct-2022 from the other health care professional via Bavarian Nordic: New information included the patient's initials and age, confirmation that Jynneos was not planned to be given and information that the patient did not experience any adverse event.; Reporter's Comments: A 41-year-old female patient was vaccinated with the first dose of Jynneos vaccine on 10-Oct-2022, the dose administered was 0.3 ml intramuscularly which is considered accidental underdose and inappropriate route of product administration. Reportedly, vaccination was done by accident, Jynneos vaccine was administered instead of COVID booster, which is considered as wrong product administered. The patient did not experience adverse events. All three events are listed as per the Company conventions. Patient's medical history and concomitant medications were unknown. Inappropriate route of product administration, accidental underdose and wrong product administered are assessed as not related to the suspect vaccine, but to a human factor. The case is non-serious.; Sender's Comments: A 41-year-old female patient was vaccinated with the first dose of Jynneos vaccine on 10-Oct-2022, the dose administered was 0.3 ml intramuscularly which is considered accidental underdose and inappropriate route of product administration. Reportedly, vaccination was done by accident, Jynneos vaccine was administered instead of COVID booster, which is considered as wrong product administered. The patient did not experience adverse events. All three events are listed as per the Company conventions. Patient's medical history and concomitant medications were unknown. Inappropriate route of product administration, accidental underdose and wrong product administered are assessed as not related to the suspect vaccine, but to a human factor. The case is non-serious.