This report describes a 28-year-old man who developed multifocal mucocutaneous lesions that were temporally associated with receiving a seasonal influenza vaccination. Seven days after vaccination he presented with oral ulcerative lesions and multiple vesicular eruptions affecting the anterior chest wall, pubic region, and penile shaft. The individual did not have a known immunocompromising condition documented in the report.
The authors frame this event as a single-patient case report and note that seasonal influenza vaccination is widely implemented and generally safe, although rare immunological adverse events have been reported. The timeline—onset of lesions seven days after vaccination—is emphasized as a close temporal relationship but not evidence of causation.
Specimens were obtained from clinically apparent lesions and analyzed using a multiplex polymerase chain reaction (PCR) assay. The assay detected HSV-1 DNA in the lesion specimens. HSV-2 and other sexually transmitted pathogens included in the multiplex panel were not detected. The detection of HSV-1 DNA provided a microbiological diagnosis that correlated with the mucocutaneous presentation.
The report lists Multiplex Polymerase Chain Reaction in the indexed MeSH terms, reflecting its role in confirming the viral etiology. No additional laboratory values, imaging, or immunologic testing results were reported in the abstract.
The patient received intravenous acyclovir, an antiviral agent included among the indexed substances and MeSH terms for the report. Following administration of intravenous acyclovir, the patient experienced complete clinical resolution of the lesions, according to the authors. The MeSH indexing also lists acyclovir under administration, dosage, and therapeutic use, highlighting its role as the chosen antiviral therapy in this case.
Specific details regarding dosing, duration of therapy, inpatient versus outpatient status, or follow-up assessments beyond clinical resolution were not reported in the abstract.
The authors explicitly state that causality between the influenza vaccination and the onset of HSV-1 infection cannot be established from this single case. They note that the close temporal relationship is noteworthy while also acknowledging that alternative explanations cannot be excluded. This distinction—temporal association versus proven causation—is a central point of the report.
As a case report, the account aims to document an unusual temporal association and to prompt consideration among clinicians rather than to provide evidence of a causal vaccine adverse effect. The indexed publication types indicate this is a Case Report and the abstract frames the observation within the larger context that influenza vaccination is generally safe.
The case underscores the importance of including HSV infection in the differential diagnosis when clinicians encounter multifocal mucocutaneous lesions occurring after vaccination. The authors caution that reporting this temporal association does not imply the vaccine caused the infection.
Key practical points drawn from the report include: consider targeted diagnostic testing such as multiplex PCR when confronted with multifocal vesicular or ulcerative mucocutaneous lesions; recognize that HSV-1 can present with disseminated mucocutaneous involvement even in adults without known immunocompromise; and initiate appropriate antiviral therapy—acyclovir in this case—which was associated with clinical resolution.
The abstract does not provide guidance on vaccine counseling, risk quantification, or recommendations for vaccine administration and monitoring beyond noting the observation.
This case report was published in Human Vaccines & Immunotherapeutics (Hum Vaccin Immunother) in December 2026. The article was assigned PMID 42757534 and DOI 10.1080/21645515.2026.2735737 and was posted online Sept 18, 2026. Authors include Yen-Hung Liu and Pei-Lun Hung with affiliations to Fu Jen Catholic University School of Medicine, Cardinal Tien Hospital Division of Infectious Diseases, and National Taiwan University Hospital Department of Laboratory Medicine in Taiwan.
Indexed MeSH terms highlight topics relevant to this report, including Influenza Vaccines (adverse effects and administration), Herpes Simplex diagnosis and drug therapy, Acyclovir administration and therapeutic use, and Multiplex Polymerase Chain Reaction. The report is cataloged as a single-patient Case Report and aims to inform clinicians about an observed temporal association and its diagnostic and therapeutic course.
Limitations
This summary is based on the abstract and bibliographic entry for the case report. The abstract does not present detailed patient history beyond the absence of a known immunocompromising condition, nor does it supply antiviral dosing, duration, laboratory data other than PCR results, or long-term follow-up. Those details were not reported in the source abstract and therefore are not included here.