Allergological study in patients vaccinated against COVID-19 with suspected allergic reactions

Abstract

Background One of the main barriers to vaccination against SARS-CoV-2 is the fear of developing hypersensitivity reactions to any of its components. Although these reactions are very rare, it is necessary to establish an effective protocol to detect patients at risk of developing them. The aim of this study was to evaluate hypersensitivity reactions in vaccinated patients in order to allow or not to complete the vaccination protocol. Methods Descriptive and cross-sectional study in which patients with suspected hypersensitivity to SARS-CoV-2 vaccines were evaluated. All patients underwent skin prick test (SPT) and/or intradermal test (IDT) with the vaccines and their excipients. In patients with positive IDT with the vaccine, a histopathological and immunohistochemical study was performed by skin biopsy. A basophil activation test (BAT) and a lymphoblastic transformation test (LTT) were also performed. Results Sixteen patients with suspected hypersensitivity to SARS-CoV-2 vaccine (12 received Comirnaty®, 3 received Vaxzevria®, and 1 received Spikevax®) were evaluated. Half had immediate hypersensitivity reactions and half had delayed reactions. All SPTs to excipients and vaccines were negative. IDTs with all excipients were negative. IDTs with vaccines were positive in 11 patients and negative in 5. The histological and immunohistochemical study of the two selected patients with positive IDT with vaccine showed T-lymphocyte involvement. BAT and LTT were negative in both cases. The vaccination protocol could be completed in 7 of 16 patients (44%) studied. The remaining 9 patients did not receive the second dose: 5 because vaccination was not required and 4 because they refused to be vaccinated. Conclusions Thanks to the allergological and immunohistochemical study, the vaccination protocol could be completed in about half of the patients who presented suspected hypersensitivity reactions to SARS-CoV-2 vaccines. IDTs with vaccines could be a valuable method for assessing the immunogenicity of the vaccines.

Immune-Mediated Organ-Specific Reactions to COVID-19 Vaccines: A Retrospective Descriptive Study

“…These ingredients had not been previously employed in vaccine manufacturing, and the experience with adverse effects and risk of allergic reactions is, therefore, limited [ 5 ]. There have already been reports of patients who have experienced immediate or delayed HRs to COVID-19 vaccines [ 19 , 21 , 22 ].…”

“…However, cases of acute, generalized, exanthematous pustulosis, erythema multiforme and other blistering rashes have also been reported [ 17 ]. Our case series of suspected delayed HRs to COVID-19 vaccines included a case of erythema multiforme and other systemic reactions that have already been reported [ 18 , 21 , 24 , 25 , 26 , 27 , 28 ].…”

“…The vaccine component(s) responsible for these HRs and the underlying mechanisms remain to be elucidated. Skin patch tests with excipients do not help diagnose delayed reactions [ 20 , 21 ], and, as far as we know, there has been no study to date on the contribution of lymphocyte transformation tests with the excipients of COVID-19 vaccines to diagnosing delayed HRs.…”

The role of lymphocyte transformation tests (LTT) in suspected severe delayed hypersensitivity reactions following COVID-19 vaccination

“…While it has been commonly applied in the evaluation of drugs such as antibiotics, allopurinol, and non-steroidal anti-inflammatory drugs, 4 its role in the assessment of DHRs to vaccines, in particular COVID-19 vaccines, requires further elucidation. 5 We herein describe our approach to combining LTT and skin tests (ST) for assessing two suspected cases of DHRs following ChAdOx1 or BNT162b2 COVID-19 vaccination.…”