key: cord-0854721-18i69vwu
authors: Papadimitriou, I.; Bakirtzi, K.; Sotiriou, E.; Vakirlis, E.; Hatzibougias, D.; Ioannides, D.
title: Delayed localized hypersensitivity reactions to COVID‐19 mRNA vaccines: a 6‐month retrospective study
date: 2021-08-26
journal: Clin Exp Dermatol
DOI: 10.1111/ced.14856
sha: 2d17dff046186dd65ce46717b7758cf05a676ab3
doc_id: 854721
cord_uid: 18i69vwu

Several individuals have developed delayed localized cutaneous vaccine reactions to the two novel mRNA Covid‐19 vaccines. Clinical and histopathologic results of this case series study confirm that the localized injection‐site reactions to the mRNA COVID‐19 vaccines are delayed hypersensitivity reactions that, unlike immediate hypersensitivity reactions, are not a contraindication to vaccination.[Image: see text]

vaccine type. Local ISRs preceded delayed large ISRs in 51 of the 84 patients (60.7%).

Delayed large ISRs occurred in 82 of the 84 patients after their first dose, occurring in 79 of the 84 patients (94%) approximately 9 days after the first dose (range 7-13 days). The plaques were mainly oedematous or indurated and homogeneous or annular, and subsided after a (a) (b) Figure 1 (a) Indurated erythematous patch at the injection site, 10 days after the first dose of the Moderna vaccine; (b) mild to moderate perivascular infiltrate predominantly of lymphocytes, mild dermal focal oedema with red cell extravasation and rare interstitial eosinophils (haematoxylin and eosin, original magnification 9 100). mean of 3 days (range 2-6 days) after starting treatment with topical corticosteroids and oral antihistaminic or anti-inflammatory medication (Fig. 1a) .

In addition, 37 of the 84 patients (44%) presented delayed large ISRs after their second vaccine dose; 2 of these reported having had no reaction to the first dose. ISRs after the second dose occurred sooner in the 35 patients (41.7%) who had experienced a relevant reaction to the first dose, with a mean onset of 2 days (range 1-6 days) after vaccine administration and with a similar clinical presentation. Of these, 7 (20%) experienced a more pronounced reaction with the second dose.

Histological findings were consistent with delayed localized hypersensitivity reaction, demonstrating mild to moderate perivascular lymphocytic infiltrate, mild dermal focal oedema with red cell extravasation and rare interstitial eosinophils (Fig. 1b) .

Limited data on delayed hypersensitivity reactions have been published, primarily after administration of the Moderna vaccine. [3] [4] [5] In our study, although the number of Pfizer vaccines allocated to our region was seven times that of the number of Moderna vaccines, relevant reactions presented only in individuals who received the Moderna vaccination. Therefore, it is possible that delayed localized reactions may have been underestimated in the Moderna clinical trial, as they were actively monitored for only 7 days after vaccination.

In conclusion, ISRs can occur after administration of mRNA vaccines, and may be delayed. However, AEs to mRNA vaccines are minor and self-limiting, and should not discourage vaccination.

I. Papadimitriou, 1 K. Bakirtzi, 1 E. Sotiriou, 1 E. Vakirlis, 1 D. Hatzibougias 2 and D. Ioannides 1

Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine

Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine

Delayed localized hypersensitivity reactions to the Moderna COVID-19 vaccine: a case series

Cutaneous reactions reported after Moderna and Pfizer COVID-19 vaccination: a registry-based study of 414 cases

Delayed large local reactions to mRNA-1273 vaccine against SARS-CoV-2

First Department of Dermatology and Venereology, Aristotle University of Thessaloniki, Greece and 2 Microdiagnostics Private Pathology and Molecular Laboratory, Thessaloniki, Greece E-mail: bakirtzicatherine@hotmail.com Conflict of interest: the authors declare that they have no conflicts of interest. IP and KB contributed equally to this manuscript and should be considered joint first authors. Accepted for publication 15 July 2021