Want to take quizzes and track your credits?
What are the clinical course and histopathologic examination findings for delayed injection-site reactions to the Moderna coronavirus disease 2019 (COVID-19) vaccine?
The Moderna COVID-19 vaccine may cause a delayed localized hypersensitivity reaction with a median latency to onset of 7 days after vaccine administration. This pruritic and variably tender reaction has a median duration of 5 days, but may persist for up to 21 days, and may occur again and sooner after the second vaccine dose; no serious adverse events were observed in association with this cutaneous reaction to the Moderna COVID-19 vaccine.
Self-limited localized delayed hypersensitivity reactions to the Moderna COVID-19 vaccine may occur, and in contrast with immediate hypersensitivity reactions, these delayed hypersensitivity reactions are not a contraindication to subsequent vaccination.
In response to the coronavirus disease 2019 (COVID-19) pandemic, 2 mRNA vaccines (Pfizer-BioNTech and Moderna) received emergency use authorization from the US Food and Drug Administration in December 2020. Some patients in the US have developed delayed localized cutaneous vaccine reactions that have been dubbed “COVID arm.”
To describe the course of localized cutaneous injection-site reactions to the Moderna COVID-19 vaccine, subsequent reactions to the second vaccine dose, and to characterize the findings of histopathologic examination of the reaction.
Design, Setting, and Participants
This retrospective case series study was performed at Yale New Haven Hospital, a tertiary medical center in New Haven, Connecticut, with 16 patients referred with localized cutaneous injection-site reactions from January 20 through February 12, 2021.
Main Outcomes and Measures
We collected each patient’s demographic information, a brief relevant medical history, clinical course, and treatment (if any); and considered the findings of a histopathologic examination of 1 skin biopsy specimen.
Of 16 patients (median [range] age, 38 [25-89] years; 13 [81%] women), 14 patients self-identified as White and 2 as Asian. The delayed localized cutaneous reactions developed in a median (range) of 7 (2-12) days after receiving the Moderna COVID-19 vaccine. These reactions occurred at or near the injection site and were described as pruritic, painful, and edematous pink plaques. None of the participants had received the Pfizer-BioNTech vaccine. Results of a skin biopsy specimen demonstrated a mild predominantly perivascular mixed infiltrate with lymphocytes and eosinophils, consistent with a dermal hypersensitivity reaction. Of participants who had a reaction to first vaccine dose (15 of 16 patients), most (11 patients) developed a similar localized injection-site reaction to the second vaccine dose; most (10 patients) also developed the second reaction sooner as compared with the first-dose reaction.
Conclusions and Relevance
Clinical and histopathologic findings of this case series study indicate that the localized injection-site reactions to the Moderna COVID-19 vaccine are a delayed hypersensitivity reaction. These reactions may occur sooner after the second dose, but they are self-limited and not associated with serious vaccine adverse effects. In contrast to immediate hypersensitivity reactions (eg, anaphylaxis, urticaria), these delayed reactions (dubbed “COVID arm”) are not a contraindication to subsequent vaccination.
Sign in to take quiz and track your certificates
JN Learning™ is the home for CME and MOC from the JAMA Network. Search by specialty or US state and earn AMA PRA Category 1 CME Credit™ from articles, audio, Clinical Challenges and more. Learn more about CME/MOC
Accepted for Publication: March 18, 2021.
Published Online: May 12, 2021. doi:10.1001/jamadermatol.2021.1214
Corresponding Author: Alicia J. Little, MD, PhD, Department of Dermatology, Yale School of Medicine, 333 Cedar St, PO Box 208059, New Haven, CT 06520 (email@example.com).
Author Contributions: Drs Little and Johnston had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: All authors.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Johnston, Galan, Little.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Johnston, Little.
Administrative, technical, or material support: Johnston, Galan, Watsky.
Conflict of Interest Disclosures: Dr Little reported a grant from the National Center for Advancing Translational Science (CTSA No. KL2 TR001862), which is a component of the National Institutes of Health, and a Women’s Health Career Development Award from the Dermatology Foundation during the conduct of the study. Dr Watsky reported equity in Johnson & Johnson held by his spouse’s retirement fund outside the submitted work. No other disclosures were reported.
Disclaimer: The publication's contents are solely the responsibility of the authors and do not necessarily represent the official view of the National Institutes of Health.
Additional Contributions: We thank the 4 patients whose images were published for granting permission. We thank Christine Ko, MD, Department of Dermatology, Yale University School of Medicine, for mentorship and assistance with editing the manuscript. For assistance with referred patients, we thank Jacob Siegel, MD, Kathleen Suozzi, MD, Mark Goldstein, MD, Mark Grossman, MD, and Barry Richter, MD, Department of Dermatology, Yale University School of Medicine, and Mark Abdelmalek, MD, Dermatology of Philadelphia–Mohs Surgery Center and Department of Dermatology, University of Pennsylvania Perelman School of Medicine. We thank Gauri Panse, MD, Departments of Dermatology and Pathology, Yale University School of Medicine, for assistance with reviewing the histopathology findings. We thank Mary Tomayko, MD, PhD, Department of Dermatology, Yale University School of Medicine, for insights into potential immunopathogenesis of “COVID arm.” We thank David Banach, MD, Department of Medicine (Infectious Disease), University of Connecticut School of Medicine, and Richard Martinello, MD, Departments of Medicine (Infectious Disease) and Pediatrics, Yale University School of Medicine and Department of Infection Prevention, Yale New Haven Health, for insights into SARS-CoV-2 vaccine administration and reported adverse effects. None of these individuals were compensated.
You currently have no searches saved.