---
title: "Multifocal mucocutaneous HSV-1 infection after seasonal influenza vaccination in a young adult"
id: "pubmed-42757534"
canonical_url: "https://medichelpline.com/clinical-feed/pubmed-42757534"
content_type: "clinical_feed_article"
specialty: "Pharmacology"
source_name: "PubMed / NCBI"
source_url: "https://pubmed.ncbi.nlm.nih.gov/42757534/"
doi: "10.1080/21645515.2026.2735737"
published_at: "2026-09-18T12:00:00.000Z"
evidence_level: "Case Reports"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Multifocal mucocutaneous HSV-1 infection after seasonal influenza vaccination in a young adult
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/pubmed-42757534
- **Specialty:** [Pharmacology](https://medichelpline.com/clinical-feed/pharmacology.md)
- **Primary Source:** PubMed / NCBI
- **Source URL:** [Original Journal Publication](https://pubmed.ncbi.nlm.nih.gov/42757534/)
- **DOI:** [10.1080/21645515.2026.2735737](https://doi.org/10.1080%2F21645515.2026.2735737)
- **Published At:** 2026-09-18T12:00:00.000Z
- **Evidence Rating:** Case Reports
## Executive GIST (TL;DR)
- Case report of a 28-year-old man who developed **multifocal mucocutaneous Herpes simplex virus type 1 (HSV-1)** infection seven days after receiving seasonal **influenza vaccination**. - Clinical presentation included oral ulcerative lesions and multiple vesicular eruptions on the anterior chest wall, pubic region, and penile shaft. - Diagnostic testing: a multiplex polymerase chain reaction (PCR) assay on lesion specimens detected **HSV-1 DNA**; HSV-2 and other sexually transmitted pathogens in the assay were not detected. - Management: intravenous **acyclovir** was administered and led to complete clinical resolution. - Authors emphasize the temporal association but explicitly state that **causality cannot be established** and alternative explanations were not excluded. - The report highlights the need to include HSV infection in the differential diagnosis of multifocal mucocutaneous lesions occurring after influenza vaccination, without implying a causal relationship. - Publication details: case report published in Hum Vaccin Immunother (Dec 2026); PMID 42757534; DOI 10.1080/21645515.2026.2735737. - Affiliations: authors from Fu Jen Catholic University School of Medicine, Cardinal Tien Hospital Division of Infectious Diseases, and National Taiwan University Hospital Department of Laboratory Medicine. - Key MeSH terms and indexed topics include influenza vaccines (adverse effects), herpes simplex diagnosis and therapy, acyclovir administration, and multiplex PCR.
## Clinical Analysis & Structured Key Points
Seasonal influenza vaccination is widely implemented and generally safe; however, rare immunological adverse events have been reported. We describe a case of multifocal mucocutaneous Herpes simplex virus type 1 (HSV-1) infection temporally associated with seasonal influenza vaccination in a 28-year-old man without a known immunocompromising condition. Seven days after vaccination, he developed oral ulcerative lesions and multiple vesicular eruptions involving the anterior chest wall, pubic region, and penile shaft. A multiplex polymerase chain reaction assay performed on specimens obtained from clinically apparent lesions detected HSV-1 DNA, whereas HSV-2 and other sexually transmitted pathogens included in the assay were not detected. Intravenous acyclovir was administered, resulting in complete clinical resolution. Although causality cannot be established, the close temporal relationship between influenza vaccination and the onset of HSV-1 infection is noteworthy, while alternative explanations cannot be excluded. This case highlights the importance of considering HSV infection in the differential diagnosis of multifocal mucocutaneous lesions occurring after influenza vaccination without implying a causal relationship.
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