Monkeypox positive; Vaccination failure of the monkeypox vaccination; Case reference number US-BN-2023-001786 is a spontaneous case report initially received from a nurse via Health Agency (reference number: USBA23-1880) on 10-Nov-2023 and concerns a 29-year-old male patient.    The patient's medical history and concomitant medication details were not provided.   On an unspecified date, reported as in the summer 2023, the patient was vaccinated with unspecified number of doses of Jynneos (batch number: unknown) at an unknown dose, route or site of administration, for indication reported as monkeypox vaccination.  On 31-Oct-2023, an unknown amount of time after receiving Jynneos, the patient had vaccination failure of the monkeypox vaccination and was found to be monkeypox positive, as reported.  On unspecified date, the patient was hospitalized. As reported, supportive care was given to the patient and unspecified laboratory tests were performed.  At the time of the initial report, the outcome for the events of vaccination failure and monkeypox was unknown.  The reporter assessed the events of vaccination failure and monkeypox as serious due to criteria of hospitalization and related to Jynneos vaccination. Additionally, the events of vaccination failure and monkeypox were assessed as serious due to criteria of medical significance.  No further information was provided.; Reporter's Comments: A 29-year-old male patient had vaccination failure of the monkeypox vaccination and was found to be monkeypox positive unknown time after vaccination with unspecified number of doses of Jynneos. Monkeypox is unlisted according to Health  Agency and Regulatory Authority while vaccination failure is considered listed per company convention. The outcome was unknown. The patient's medical history and concomitant medication details were not provided. Considering that Jynneos is a non-replicating vaccine which does not contain the monkeypox and since vaccination with the product may not result in protection in all cases, the event is assessed as not related to Jynneos. Vaccination failure is assessed as not related to suspect product since it was unknown if the patient received full course of vaccination. The case is serious due to seriousness criteria of hospitalization and medical significance of vaccination failure.; Sender's Comments: A 29-year-old male patient had vaccination failure of the monkeypox vaccination and was found to be monkeypox positive unknown time after vaccination with unspecified number of doses of Jynneos. Monkeypox is unlisted according to Health Agency and Regulatory Authority while vaccination failure is considered listed per company convention. The outcome was unknown. The patient's medical history and concomitant medication details were not provided. Considering that Jynneos is a non-replicating vaccine which does not contain the monkeypox and since vaccination with the product may not result in protection in all cases, the event is assessed as not related to Jynneos. Vaccination failure is assessed as not related to suspect product since it was unknown if the patient received full course of vaccination. The case is serious due to seriousness criteria of hospitalization and medical significance of vaccination failure.