Localized Delayed T-cell Mediated Hypersensitivity After mRNA SARS-CoV-2 Vaccination.

Since the emergency authorization of SARS-CoV-2 vaccines, the medical literature has been investigating the management of allergic reactions to the vaccines. Anaphylaxis has been reported among a minority of vaccinated individuals, and many trials monitoring the safety profile of the vaccines have identified cases of benign cutaneous reactions. Typical features of delayed benign cutaneous hypersensitivity reactions include localized erythema, pruritus, and rash. However, reports have described rare cases of rash and atopy at sites apart from the injection site following vaccine delivery. We will discuss a unique case of delayed benign cutaneous hypersensitivity presenting in the lower extremity after an upper-extremity administration of an mRNA SARS-CoV-2. Additionally, we describe management strategies to guide clinicians who encounter similar vaccine-induced hypersensitivity reactions.

Delayed systemic urticarial reactions following mRNA COVID-19 vaccination.

Background: As the vaccination campaign in response to the coronavirus disease 2019 (COVID-19) pandemic continues, concerns with regard to adverse reactions to the vaccine remain. Although immediate hypersensitivity reactions have received much attention, delayed systemic urticarial reactions after vaccination can occur. Objective: To describe the clinical presentation, vaccine excipient skin testing results, and outcomes of subsequent COVID-19 vaccination in patients who experienced delayed systemic urticarial reactions after messenger RNA (mRNA) COVID-19 vaccination. Methods: This was a retrospective case series of 12 patients referred to the Mayo Clinics in Rochester, Minnesota, and Jacksonville, Florida, between January 19, 2021, and April 30, 2021, for evaluation of delayed systemic urticarial reactions after mRNA COVID-19 vaccination. Demographics, medical and allergic history, reaction details, vaccine excipient skin testing results (when performed), and the outcome after subsequent vaccination were collected for each patient. Results: The mean age of the patients was 52 years, all were white, and 9 (75%) were women. Half of the patients had a history of drug allergy, and one had a history of chronic spontaneous urticaria. Seven patients reacted to the Pfizer-BioNTech vaccine and five reacted to the Moderna vaccine. Seven patients developed symptoms between 8 and 24 hours after vaccination. Nine patients required antihistamines for treatment. The median time to symptom resolution was 4 days. Nine patients underwent allergist-directed COVID-19 vaccine excipient skin testing, all of which were negative. Ten patients chose to receive their next mRNA COVID-19 vaccine dose, and four patients experienced recurrent delayed urticaria. Conclusion: Delayed systemic urticarial reactions after mRNA COVID-19 vaccination were not life-threatening, could be treated with antihistamines, and were not predicted with vaccine excipient skin testing. They were not a contraindication to subsequent vaccination, although patients should be counseled with regard to the possibility of recurrence.

Utility and futility of skin testing to address concerns surrounding messenger RNA coronavirus disease 2019 vaccine reactions.

BACKGROUND: The mechanism of coronavirus disease 2019 (COVID-19) vaccine hypersensitivity reactions is unknown. COVID-19 vaccine excipient skin testing has been used in evaluation of these reactions, but its utility in predicting subsequent COVID-19 vaccine tolerance is also unknown. OBJECTIVE: To evaluate the utility of COVID-19 vaccine and vaccine excipient skin testing in both patients with an allergic reaction to their first messenger RNA COVID-19 vaccine dose and patients with a history of polyethylene glycol allergy who have not yet received a COVID-19 vaccine dose. METHODS: In this multicenter, retrospective review, COVID-19 vaccine and vaccine excipient skin testing was performed in patients referred to 1 of 3 large tertiary academic institutions. Patient medical records were reviewed after skin testing to determine subsequent COVID-19 vaccine tolerance. RESULTS: A total of 129 patients underwent skin testing, in whom 12 patients (9.3%) had positive results. There were 101 patients who received a COVID-19 vaccine after the skin testing, which was tolerated in 90 patients (89.1%) with no allergic symptoms, including 5 of 6 patients with positive skin testing results who received a COVID-19 vaccine after the skin testing. The remaining 11 patients experienced minor allergic symptoms after COVID-19 vaccination, none of whom required treatment beyond antihistamines. CONCLUSION: The low positivity rate of COVID-19 vaccine excipient skin testing and high rate of subsequent COVID-19 vaccine tolerance suggest a low utility of this method in evaluation of COVID-19 vaccine hypersensitivity reactions. Focus should shift to the use of existing vaccine allergy practice parameters, with consideration of graded dosing when necessary. On the basis of these results, strict avoidance of subsequent COVID-19 vaccination should be discouraged.

COVID-19 vaccine-associated anaphylaxis: A statement of the World Allergy Organization Anaphylaxis Committee.

Vaccines against COVID-19 (and its emerging variants) are an essential global intervention to control the current pandemic situation. Vaccines often cause adverse events; however, the vast majority of adverse events following immunization (AEFI) are a consequence of the vaccine stimulating a protective immune response, and not allergic in etiology. Anaphylaxis as an AEFI is uncommon, occurring at a rate of less than 1 per million doses for most vaccines. However, within the first days of initiating mass vaccination with the Pfizer-BioNTech COVID-19 vaccine BNT162b2, there were reports of anaphylaxis from the United Kingdom and United States. More recent data imply an incidence of anaphylaxis closer to 1:200,000 doses with respect to the Pfizer-BioNTech vaccine. In this position paper, we discuss the background to reactions to the current COVID-19 vaccines and relevant steps to mitigate against the risk of anaphylaxis as an AEFI. We propose a global surveillance strategy led by allergists in order to understand the potential risk and generate data to inform evidence-based guidance, and thus provide reassurance to public health bodies and members of the public.