Monkeypox; The patient received the first dose of Jynneos vaccine in August 2022; Literature citation:  Case reference number US-BN-2023-000580 is a literature case report, title as stated above, identified on 28-Mar-2023 and concerns an adult male patient of unknown age, reported as below 50 years, first out of three.  The aim of the article was to assess monkeypox (mpox) prevalence in several specimen types and evaluate for undiagnosed infection among patients without characteristic mpox skin lesions who engaged in behaviors associated with mpox transmission and presented for Jynneos vaccine. 543 patients were involved with median age 33 years (range: 18-87). Enrolled patients were without self-reported characteristic mpox rash presenting for their first dose of Jynneos vaccine at two clinics between 11-Aug-2022 and 31-Aug2022. The assessment spanned three clinic visits across two months but data collected at the first visit was presented. Following vaccination and informed consent, patients completed a questionnaire that captured demographics, symptoms, medical history, recent exposures, and behaviors, blood specimens were collected, pharyngeal swabs (clinician-collected or self-collected), and rectal swabs (all self-collected). The biological specimens were processed and tested for mpox DNA via real-time polymerase chain reaction (PCR) using a CDC-developed mpox virus-clade II specific assay. Serum was tested for anti-orthopoxvirus IgM and IgG antibodies. Demographic, clinical, and behavioral factors were described among participants who provided more than 1 laboratory specimen. Findings suggested minimal undetected infection.   On an unspecified date, reported as between 11-Aug-2022 and 31-Aug-2022, first of the three patients was vaccinated with the first dose of Jynneos vaccine (batch number: unknown), at an unknown dose, via unknown route of administration, in the left arm, for unknown indication (explicitly coded as 'incomplete course of vaccination'). The patient had HIV, no previous smallpox or mpox vaccination and did not have a known mpox case contact in the 14 days prior nor reported any symptoms.   On an unspecified date, unspecified amount of time after Jynneos vaccination, a pharyngeal specimen was PCR-positive for mpox DNA. The average Ct value for the pharyngeal specimen was 32.98 (units not provided). No blood specimens were PCR positive for mpox DNA. The patient was without characteristic rash and had evidence of contemporaneous mpox virus infection. The patient did not have IgG-positive result but had IgM positive result, likely related to contemporaneous mpox infection, as reported.   Limitations of the study were reported as the analysis being limited to patients presenting for Jynneos vaccine at two urban clinics and results might have not been generalizable to all individuals engaged in behaviors associated with mpox virus transmission, questionnaire data were subject to recall bias, specifically regarding information used to help interpret serologic results, including previous smallpox vaccination history, and while the patient with PCR-positive specimen reported no skin lesions or rash at the time of specimen collection, it was possible that mpox lesions shedding virus were present in anatomic sites not readily visualized (e.g., rectum, oropharynx) nor identified by the patient, as reported.  On an unspecified date, approximately 28 days after PCR-positive results, two out of three patients had reported no skin lesions or rash at the second visit.  The reporter did not provide seriousness and causality assessment of the event of monkeypox. However, the event of monkeypox was assessed as serious due to medical significance.  This case is linked with the cases US-BN-2023-000638 and US-BN-2023-000639 (same reporter).  No further information was provided.; Reporter's Comments: An adult male patient of unknown age, reported as below 50 years was vaccinated with the first dose of Jynneos vaccine, at an unknown dose, via unknown route of administration, in the left arm, on an unspecified date, reported as between 11-Aug-2022 and 31-Aug-2022, for unknown indication, which is considered as incomplete course of vaccination. On an unspecified date, unspecified amount of time after Jynneos vaccination, a pharyngeal specimen was PCR-positive for mpox DNA (medical significance). Monkeypox is unlisted for Jynneos according to the CCDS and PI, whilst incomplete course of vaccination is considered as listed per company convention. The outcome was unknown. Considering that the vaccine is non-replicating and does not contain monkeypox virus, monkeypox has been assessed as not related to Jynneos. Incomplete course of vaccination has been assessed as not related to the suspect vaccine, but to a human factor. This case is considered as serious due to medical significance.; Sender's Comments: An adult male patient of unknown age, reported as below 50 years was vaccinated with the first dose of Jynneos vaccine, at an unknown dose, via unknown route of administration, in the left arm, on an unspecified date, reported as between 11-Aug-2022 and 31-Aug-2022, for unknown indication, which is considered as incomplete course of vaccination. On an unspecified date, unspecified amount of time after Jynneos vaccination, a pharyngeal specimen was PCR-positive for mpox DNA (medical significance). Monkeypox is unlisted for Jynneos according to the CCDS and PI, whilst incomplete course of vaccination is considered as listed per company convention. The outcome was unknown. Considering that the vaccine is non-replicating and does not contain monkeypox virus, monkeypox has been assessed as not related to Jynneos. Incomplete course of vaccination has been assessed as not related to the suspect vaccine, but to a human factor. This case is considered as serious due to medical significance.