The second dose of Jynneos vaccine administered intradermally; The second dose of Jynneos vaccine administered at a dose of 0.1 ml; Blisters then leaking at injection site during the night; Blisters then leaking at injection site during the night; Case reference number US-BN-2022-002198 is a spontaneous case report initially received on 01-Sep-2022 from a physician via Communications (reference number: USBAV22-1255) and concerns a 40-year-old male patient.  The patient's medical history was not provided.  The patient's concomitant medication included Truvada (emtricitabine, tenofovir disoproxil fumarate).  On 02-Aug-2022, the patient was vaccinated with the first dose of Jynneos vaccine (Smallpox and Monkeypox Vaccine, Live, Nonreplicating; batch number: FDP00013), at dose reported as 0.5 ml, administered subcutaneously, at unknown anatomical location for monkeypox prophylaxis.  On 30-Aug-2022, 28 days after the first vaccination, the patient was vaccinated with the second dose of Jynneos vaccine (Smallpox and Monkeypox Vaccine, Live, Nonreplicating; batch number: FDP00013), at a dose reported as 0.1 ml, administered intradermally, at unknown anatomical location, for monkeypox prophylaxis (explicitly coded as 'incorrect route of product administration' and 'underdose')  On 31-Aug-2022, one day after the second Jynneos dose, also reported as during the night, the patient's injection site first blistered than leaked. The patient bandaged it and reported that it did not look infected.  At the time of this report, the outcome of the events of 'injection site leaking' and 'injection site blisters' was reported as not resolved/ongoing.  The reporter assessed both the events as non serious and possibly related to Jynneos.  Additional information received on 01-Sep-2022 included local BN case ID.; Reporter's Comments: A 40-year-old male patient was vaccinated with the second dose of Jynneos vaccine, at a dose reported as 0.1 ml, administered intradermally, at unknown anatomical location, for monkeypox prophylaxis, which is considered as incorrect route of product administration and underdose. On the day 1 after the second dose, the patient experienced non-serious events of injection site extravasation and injection site vesicles. Incorrect route of product administration and underdose are considered as listed per company convention. Injection site extravasation is unlisted per RA v1 and RA, whilst injection site vesicles is listed per RA v1 and unlisted per RA. The patient's medical history was not provided, and concomitant medication included Truvada (emtricitabine, tenofovir disoproxil fumarate). The outcome of the events was reported as not resolved. Considering plausible temporal relationship and since the contributory role of the suspect vaccine cannot be fully excluded, the events of injection site extravasation and injection site vesicles have been considered as related to Jynneos. Incorrect route of product administration and underdose have been considered as not related to the suspect vaccine, but to a human factor. This case is considered as non-serious.; Sender's Comments: A 40-year-old male patient was vaccinated with the second dose of Jynneos vaccine, at a dose reported as 0.1 ml, administered intradermally, at unknown anatomical location, for monkeypox prophylaxis, which is considered as incorrect route of product administration and underdose. On the day 1 after the second dose, the patient experienced non-serious events of injection site extravasation and injection site vesicles. Incorrect route of product administration and underdose are considered as listed per company convention. Injection site extravasation is unlisted per RA v1 and RA, whilst injection site vesicles is listed per RA v1 and unlisted per RA. The patient's medical history was not provided, and concomitant medication included Truvada (emtricitabine, tenofovir disoproxil fumarate). The outcome of the events was reported as not resolved. Considering plausible temporal relationship and since the contributory role of the suspect vaccine cannot be fully excluded, the events of injection site extravasation and injection site vesicles have been considered as related to Jynneos. Incorrect route of product administration and underdose have been considered as not related to the suspect vaccine, but to a human factor. This case is considered as non-serious.