The COVID-19 Pandemic in 2021: Avoiding Overdiagnosis of Anaphylaxis Risk While Safely Vaccinating the World

Patient-Centered Practice Guidelines: GRADEing Evidence to Incorporate Certainty, Balance Between Benefits and Harms, Equity, Feasibility, and Cost-Effectiveness

The practice of medicine in recent years has emphasized the use of evidence-based clinical guidelines to help inform treatment decisions. Since its development in 2004, the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach has offered a systematic process for reviewing and summarizing the certainty of evidence found in the medical literature regarding various treatment options. To develop truly patient-centered care guidelines, this appraisal of the certainty of evidence must be combined with an understanding of the balance between benefits and harms, patient preferences, equity, feasibility, cost-effectiveness, and policy implications. This review examines each of these domains in detail, exploring the process and benefits of developing relevant, patient-focused guidelines directly applicable to the practice of modern medicine.

A practical guide to address reactions to vaccines in children

Currently available vaccines are safe, but, potentially, any vaccine can cause an allergic reaction and, albeit very rare, anaphylaxis can occur. Although its rarity, the precise diagnostic management of a suspected anaphylaxis postvaccination is of paramount importance due to the risk of a potentially serious reaction after re-exposure, while a misdiagnosis might lead to an increase in the number of children that interrupt vaccinations resulting in an unjustifiably individual and collective risk of loss of protection against immune preventable diseases. In the light that most cases of suspected allergy to a vaccine are not effectively confirmed in up to 85% of the cases referred for an allergy evaluation, patients can continue the vaccination schedule with the same formulation and tolerance of the booster doses. The patient assessment has to be done by an expert in the vaccine field, usually an allergist or an immunologist depending on the country, to select subjects at risk of allergic reactions and to perform the correct procedures for vaccine hypersensitivity diagnosis and management, in order to guarantee safe immunization practices. The aim of this review is to provide a practical guidance for the safe management of allergic children undergoing immunization procedures. The guide is referred both to the evaluation of children who have previously experienced a suspected allergic reaction to a specific vaccine and their management in case of further booster doses, and to children allergic to a component of the vaccine to be administered.

Pearls for practice from the 2022 joint task force drug allergy practice parameter

PURPOSE OF REVIEW

To review updated recommendations in the 2022 Drug Allergy Practice Parameters for the evaluation and management of drug hypersensitivity reactions.

RECENT FINDINGS

Adverse drug reactions have become increasingly prominent with the advent of new and emerging pharmacologic therapies. Hypersensitivity reactions encompass a significant proportion of adverse drug reactions and negatively impact both the individual patient and overall health system. Reactions are heterogeneous in presentation and may be immediate (onset of symptoms ≤6 h) or delayed (onset of symptoms >6 h to months) after drug exposure. The 2022 Drug Allergy Practice Parameter provides consensus-based statements for evaluation of hypersensitivity reactions to antibiotics, NSAIDs, cancer chemotherapies, immune checkpoint inhibitors, biologics, and excipients. In general, the guideline highlights the importance of patient history in elucidating the phenotype and severity of the index reaction. Drug challenge remains the gold standard for diagnosis and is increasingly favored over skin testing in patients with nonsevere, nonanaphylactic drug reaction histories.

SUMMARY

The 2022 Drug Allergy Practice Parameter provides an updated framework for physicians to reference in clinical practice when managing patients with drug hypersensitivity reactions.

Responding to COVID-19 vaccine-related safety events: WHO Western Pacific regional experience and lessons learned

Problem

Novel vaccines were developed in an unprecedentedly short time in response to the global coronavirus disease (COVID-19) pandemic, which triggered concerns about the safety profiles of the new vaccines. This paper describes the actions and outcomes of three major adverse events of special interest (AESIs) reported in the World Health Organization's (WHO's) Western Pacific Region: anaphylaxis, thrombosis with thrombocytopenia syndrome (TTS) and post-vaccination death.

Context

During the large-scale introduction of various novel COVID-19 vaccines, robust monitoring of and response to COVID-19 vaccine safety events were critical.

Action

We developed and disseminated information sheets about anaphylaxis and TTS; provided tailor-made training for anaphylaxis monitoring and response, webinars about TTS and AESIs, and an algorithm to support decision-making about AESIs following immunization; as well as provided country-specific technical support for causality assessments, including for possible vaccination-related deaths.

Outcome

Each major vaccine event and situation of high concern was responded to appropriately and in a timely manner with comprehensive technical support from WHO. Our support activities have not only strengthened countries' capacities for vaccine safety surveillance and response, but also enabled countries to decrease the negative impact of these events on their immunization programmes and maintain the confidence of health-care professionals and the general population through proactive delivery of risk communications.

Discussion

This paper summarizes selected, major AESIs following COVID-19 vaccination and responses made by WHO's Regional Office for the Western Pacific to support countries. The examples of responses to vaccine safety events during the pandemic and unprecedented mass vaccination campaigns could be useful for countries to adopt, where applicable, to enhance their preparation for activities related to monitoring vaccine safety.

Increasing the COVID-19 immunization rate through allergy testing

BACKGROUND

Vaccination of the population is required to combat the COVID-19 pandemic. Allergy testing could reduce anxiety towards COVID-19 vaccination and thereby may increase vaccination rate, however, its effectiveness remains unclear.

METHODS

One hundred and thirty prospective real-life patients in need of but not daring to get vaccinated asked for allergy workup for COVID-19 vaccine hypersensitivity in 2021/2022. Characterization of patients, identification of anxieties, decrease of patient's anxiety levels, overall vaccination rate and adverse reactions after vaccination were assessed.

RESULTS

Tested patients were characterized by being female (91.5%) and having a high rate of previous allergies (e.g. to food 55.4%, drugs 54.6%, or previous vaccinations 50%) and dermatological disease (29.2%) but not always had medical contraindications for COVID-19 vaccination. Sixty one patients (49.6%) were highly concerned (4-6, Likert scale 0-6) about vaccination and 47 (37.6%) expressed resolving thoughts about vaccinaion anaphylaxis (3-6, Likert scale 0-6). However only 35 patients (28.5%) were scared of getting COVID-19 within 2 months (4-6, Likert scale 0-6) and only 11 (9%) patients had high expectations of getting COVID-19 (4-6, Likert scale 0-6). Allergy testing significantly (p < 0.01 to p < 0.05 respectively) reduced the median anxiety of allergic symptoms following vaccination: dyspnoea (4.2-3.1), to faint (3.7-2.7), long-term consequences (3.6-2.2), pruritus (3.4-2.6), skin rash (3.3-2.6) and death (3.2-2.6). After allergy testing, most patients (108/122, 88.5%) let themselves be vaccinated within 60 days. Revaccinated patients with previous symptoms experienced a reduction of symptoms (p < 0.05) upon revaccination.

CONCLUSIONS

Patients not daring to get vaccinated have more anxiety towards vaccination than to acquire COVID-19. For those, allergy testing excludes vaccine allergy, and is a tool to increase vaccination willingness and thereby helps to combat vaccination hesitancy.

Value-Based, Cost-Effective Care: The Role of the Allergist-Immunologist

Asthma and allergic disease impact millions of patients and are associated with high costs. Up to 30% of all medical care involves wasted spending. Across the spectrum of care provided by the allergist-immunologist, there are opportunities to improve value and reduce medical waste. Several examples highlight this reality. Evidence suggests that most patients may receive cost-effective care in the management of chronic spontaneous urticaria without the need for laboratory testing. For patients with asthma, although a single maintenance and reliever therapy approach may be cost-effective, insurance-mandated therapy changes are not, and may harm patients. Biologics may be very effective in improving asthma control but are too expensive for this indication-as demonstrated by cost-effectiveness analyses and highlighted by the Institute of Clinical and Economic Review, which concluded that the value-based price for asthma biologics ranges between $6500 and 14,3000 per year. Early introduction may prevent food allergy, but screening before first introduction is neither necessary nor cost-effective, although early salvage food oral immunotherapy may result in improved quality of life and cost savings. Evidence does not support the presence of allergic disease as a risk factor for anaphylaxis to coronavirus disease 2019 vaccination, and risk-stratified vaccination approaches do not appear cost-effective. Allergen immunotherapy is a very cost-effective treatment option. The practice of allergy-immunology has continued to evolve in recent years and can provide a leading example of high-value practice.

PEG allergy - A COVID-19 pandemic-made problem? A German perspective

Background

Polyethylene glycol (PEG) has been used for decades, but only caused allergic reactions exceptionally. Introduction of PEG-containing COVID-19 vaccines might have fostered public interest beyond medical reasoning.

Objectives

To investigate the impact of the SARS-CoV-2 pandemic on the public interest in PEG allergy in Germany and the published PEG allergy cases worldwide.

Methods

A retrospective longitudinal study was conducted to measure public interest in PEG allergy analyzing Google search volume in Germany from February 2018 to January 2022. Medically confirmed “PEG allergy” cases were analyzed by looking at the numbers of PubMed case reports and case series from 1977 until January 2022.

Results

Web results in Germany before COVID-19 show search volumes related to “PEG allergy/testing” was negligible, with 10 search queries per month. The pandemic led to a >200-fold increase from 250 queries 2 years before to 55 720 queries 2 years thereafter, reflecting tremendous public interest. Additionally, the maximum monthly search volume from before to during the pandemic increased immensely for “vaccination” (57-fold), “vaccination and adverse effects” (85-fold), “vaccination and allergy” (71-fold). In contrast, the increase of publication numbers for the search term “PEG allergy” was small from 2019 to 2021 (2.5-fold). Only a very low number of 211 cases with “PEG allergy” worldwide since 1977 could be identified.

Conclusion

PEG allergy became a topic of major public interest because of COVID-19 vaccination. Scientific publications have increased to a lesser extent, probably promoted by public awareness. Conversely, the overall number of cases published with PEG allergy remain very low. The current high demand for COVID-19 vaccination allergy testing is triggered by public interest instead of medical reasoning.

Anaphylaxis and allergic reactions to COVID‐19 vaccines: A narrative review of characteristics and potential obstacles on achieving herd immunity

Background and Aims

Methods

Results

Conclusion

The adverse reactions to vaccines practice parameter 10 years on-what have we learned?

Objective

To provide updated information on the evaluation and management of adverse reactions to vaccines.

Data Sources

PubMed (MEDLINE) search since publication of a practice parameter in 2012.

Study Selections

Original articles and guidelines on adverse reactions to vaccines, including vaccines against severe acute respiratory syndrome coronavirus 2 or coronavirus disease 2019 (COVID-19).

Results

Current guidelines conclude that patients with egg allergy are not at increased risk for reaction to egg-based influenza vaccines. Except for gelatin, most patients with allergy to vaccine constituents tolerate vaccines containing them. Most patients who have immediate reactions after receiving COVID-19 vaccines go on to receive a subsequent dose uneventfully.

Conclusion

The risk of reactions to vaccination should be weighed against the risk of having a vaccine-preventable disease if the vaccine is withheld. There is no need to ask about egg allergy before the administration of influenza vaccines, including on screening forms. In most cases, an allergy to a vaccine constituent is not a contraindication to the vaccine containing it. Patients who have had possible anaphylactic reactions to vaccines should be evaluated by an allergist rather than simply being labeled allergic, because most can go on to receive subsequent doses. Most immediate reactions to COVID-19 vaccines are not allergic, and care should be taken to not label such reactions as anaphylactic. The role, if any, of polyethylene glycol in these reactions has yet to be revealed.

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.

Impact of anti-PEG antibody affinity on accelerated blood clearance of pegylated epoetin beta in mice

Antibodies that bind polyethylene glycol (PEG) can be induced by pegylated biomolecules and also exist in a significant fraction of healthy individuals who have never received pegylated medicines. The binding affinity of antibodies against PEG (anti-PEG antibodies) likely varies depending on if they are induced or naturally occurring. Anti-PEG antibodies can accelerate the clearance of pegylated medicines from the circulation, resulting in loss of drug efficacy, but it is unknown how accelerated blood clearance is affected by anti-PEG antibody affinity. We identified a panel of anti-PEG IgG and IgM antibodies with binding avidities ranging over several orders of magnitude to methoxy polyethylene glycol-epoetin beta (PEG-EPO), which is used to treat patients suffering from anemia. Formation of in vitro immune complexes between PEG-EPO and anti-PEG IgG or IgM antibodies was more obvious as antibody affinity increased. Likewise, high affinity anti-PEG antibodies produced greater accelerated blood clearance of PEG-EPO as compared to low affinity antibodies. The molar ratio of anti-PEG antibody to PEG-EPO that accelerates drug clearance in mice correlates with antibody binding avidity. Our study indicates that the bioactivity of PEG-EPO may be reduced due to rapid clearance in patients with either high concentrations of low affinity or low concentrations of high affinity anti-PEG IgG and IgM antibodies.

Immunization practices and risk of anaphylaxis: a current update, comprehensive of COVID-19 vaccination data

PURPOSE OF REVIEW

This review aims to provide an updated report in regards to the correlation between vaccines and anaphylaxis and the related risk in the population.

RECENT FINDINGS

Initial reports showed higher incidence of anaphylaxis following messenger RNA COVID-19 vaccines compared with 'routine' vaccinations, likely influenced by the great attention paid to these 'new' vaccines. However, anaphylaxis has still to be considered quite rare and its incidence will be systematically reconsidered in the light of additional data collected.

SUMMARY

Adverse reactions to vaccines are commonly reported but most of them are nonspecific mild events, whereas vaccine-related anaphylaxis is considered a rare event, with an incidence rate equal to 1.3 cases per million vaccine doses administered. As anaphylaxis reports usually start to be reported to passive pharmacovigilance during postmarketing surveillance, the first data are used to be influenced by under- and over-reporting and lack of denominators and following studies are needed to confirm the causal relationship. This might create an initial overcautiously approach to new immunization practices but, being anaphylaxis a potential life-threatening event, every suspected contraindication has to be deepened to maximize effectiveness and safety profile and constantly redefined not to exclude an overestimated population group who could receive the vaccine uneventfully.

COVID-19 vaccines and vaccine hesitancy: Role of the allergist/immunologist in promotion of vaccine acceptance

Background: Vaccine hesitancy has been defined as a delay in acceptance or refusal of vaccines, despite the availability of vaccine services. In the past, despite an impressive record of vaccine effectiveness in the United States, several factors have contributed to a decreased acceptance of vaccines that has resulted in outbreaks of infectious diseases, e.g., measles. More recently, vaccine hesitancy has spread to coronavirus disease 2019 (COVID-19) vaccines. There are many causes of vaccine hesitancy, such as misinformation, fallacies, and myths, that have contributed to vaccine hesitancy. Objective: The purpose of the present report is to address the many causes of vaccine hesitancy and to suggest ways that the allergist/immunologist can be involved in the promotion of vaccine acceptance. Methods: The current COVID-19 vaccines were reviewed, together with their mechanisms(s) of action and adverse reactions to them. Results: The many causes of vaccine hesitancy include many doubts and concerns related to COVID-19 vaccines as well as a diminished level of confidence and trust by segments of the public in the nation's leaders in government, medical, and business communities, that those groups once enjoyed. Conclusion: Vaccination with COVID-19 vaccines is the only way that COVID-19 will be eliminated or at least controlled today, and vaccine hesitancy is the potential nemesis. The present report describes how the allergist/immunologist not only plays a major role in the delivery of specialized therapy of COVID-19 but also in educating the public with regard to the importance of COVID-19 vaccines, in dispelling misinformation, and in promoting trust for vaccine acceptance but must be informed with the most accurate and current information to do so.

Delayed skin reaction after mRNA-1273 vaccine against SARS-CoV-2: a rare clinical reaction

Background

The coronavirus disease 2019 (COVID‐19) is associated with a wide clinical spectrum of skin manifestations, including urticarial, vesicular, vasculitic and chilblain‐like lesions. Recently, delayed skin reactions have been reported in 1% individuals following mRNA vaccination against SARS-CoV-2. The exact pathophysiology and the risk factors still remain unclear.

Patients and methods

6821 employees and patients were vaccinated at our institutions between February and June 2021. Every patient received two doses of the mRNA-1273 vaccine in our hospitals, and reported back in case of any side effects which were collected in our hospital managed database.

Results

Eleven of 6821 vaccinated patients (0.16%) developed delayed skin reactions after either the first or second dose of the mRNA-1273 vaccine against SARS-CoV-2. Eight of 11 patients (73%) developed a rash after the first dose, while in 3/11 (27%), the rash occurred after the second dose. More females (9/11) were affected. Four of 11 patients required antihistamines, with two needing additional topical steroids. All the cutaneous manifestations resolved within 14 days. None of the skin reactions after the first dose of the vaccine prevented the administration of the second dose. There were no long-term cutaneous sequelae in any of the affected individuals.

Conclusion

Our data suggests that skin reactions after the use of mRNA-1273 vaccine against SARS-CoV-2 are possible, but rare. Further studies need to be done to understand the pathophysiology of these lesions.

First-Dose mRNA COVID-19 Vaccine Allergic Reactions: Limited Role for Excipient Skin Testing

BACKGROUND

The Centers for Disease Control and Prevention state that a severe or immediate allergic reaction to the first dose of an mRNA COVID-19 vaccine is a contraindication for the second dose.

OBJECTIVE

To assess outcomes associated with excipient skin testing after a reported allergic reaction to the first dose of mRNA COVID-19 vaccine.

METHODS

We identified a consecutive sample of patients with reported allergic reactions after the first dose of mRNA COVID-19 vaccine who underwent allergy assessment with skin testing to polyethylene glycol (PEG) and, when appropriate, polysorbate 80. Skin testing results in conjunction with clinical phenotyping of the first-dose mRNA COVID-19 vaccine reaction guided second-dose vaccination recommendation. Second-dose mRNA COVID-19 vaccine reactions were assessed.

RESULTS

Eighty patients with reported first-dose mRNA COVID-19 vaccine allergic reactions (n = 65; 81% immediate onset) underwent excipient skin testing. Of those, 14 (18%) had positive skin tests to PEG (n = 5) and/or polysorbate 80 (n = 12). Skin testing result did not affect tolerance of the second dose in patients with immediate or delayed reactions. Of the 70 patients who received the second mRNA COVID-19 vaccine dose (88%), 62 had either no reaction or a mild reaction managed with antihistamines (89%), but 2 patients required epinephrine treatment. Three patients with positive PEG-3350 intradermal (methylprednisolone) testing tolerated second-dose mRNA COVID-19 vaccination. Refresh Tears caused nonspecific skin irritation.

CONCLUSIONS

Most individuals with a reported allergic reaction to the first dose of mRNA COVID-19 vaccines, regardless of skin test result, received the second dose safely. More data are needed on the value of skin prick testing to PEG (MiraLAX) in evaluating patients with mRNA COVID-19 vaccine anaphylaxis. Refresh Tears should not be used for skin testing.

The Revenge of Unintended Consequences of Anaphylaxis-Risk Overdiagnosis: How Far We Have Come and How Far We Have to Go

Overdiagnosis of anaphylaxis risk is an underappreciated aspect of anaphylaxis prevention. Whereas the benefits of anaphylaxis-risk prevention are well known, potential harms resulting from preemptive approaches to mitigate anaphylaxis-risk are not insignificant. Still, great progress has been made in recent years to avoid the unintended consequences of anaphylaxis-risk overdiagnosis. Reflection on recent advances in the use of diagnostic testing, as well as the application of diagnostic labels, provides an important perspective to understand how far the specialty of allergy and immunology has come in improving the lives of patients and families. Examples of recent paradigm shifts in anaphylaxis-risk management include approaches to peanut allergy prevention without screening, deferral of corticosteroids to prevent biphasic anaphylaxis reactions, reevaluation of reflex use of emergency medical services for resolved community anaphylaxis, and an approach to penicillin allergy delabeling with direct oral challenge. Routine medical practices to decrease anaphylaxis risk can have lifelong impacts for patients-beyond just preventing anaphylaxis. As our understanding of these trade-offs evolves, it becomes necessary to weigh both the benefits and the harms of past management approaches. Because medicine remains a science of uncertainty and an art of probability, a critical approach to risk mitigation remains necessary to find the often-elusive balance in anaphylaxis prevention.

Primary care provider-reported prevalence of vaccine and polyethylene glycol allergy in Canada

Background

The coronavirus disease 2019 pandemic has highlighted the importance of accurate capture of vaccine, and vaccine component, allergy. There remains a gap in the prevalence literature from the perspective of direct primary care provider (PCP) reporting at a population level.

Objective

To determine the prevalence of PCP-documented vaccine and polyethylene glycol (PEG) allergy using electronic medical record data from the Canadian Primary Care Sentinel Surveillance Network.

Methods

Retrospective cohort study using the Canadian Primary Care Sentinel Surveillance Network repository. Machine learning algorithms were applied to evaluate for vaccine allergy documentation, and Anatomic Therapeutic Chemical codes were used for PEG allergy or allergy to common injectable medications containing PEG (CIMCP).

Results

The prevalence of PCP-documented vaccine allergy in Canada was 0.037% (395/1,055,677) and of PEG allergy was 0.0009% (10/1,055,677). In total, 0.01% of patients had a documented allergy to either PEG or CIMCP (135/1,055,677). None of the patients with PEG allergy had a documented allergy to a CIMCP. Patients with vaccine allergy and PEG allergy were significantly more likely to have other atopic comorbidities, including asthma (P < .001 for both), eczema (P < .001 and P = .001, respectively), rhinitis (P = .002 and P < .001, respectively), and food allergy (P < .001 for both). Significantly higher rates of depression (P < .001 and P < .001, respectively) and anxiety (P = .003 and P < .001, respectively) were found in those with vaccine allergy, or PEG allergy, than those without vaccine allergy or PEG allergy.

Conclusion

This is the first study to estimate the prevalence of vaccine and PEG allergy in a national cohort that uses PCP documentation, revealing a low reported rate of vaccine allergy and PEG allergy.

The Importance of a Timely Second Dose of the 2021 COVID-19 mRNA Vaccine Depends on the Protection Afforded by a First Dose and Subsequent Risk of Anaphylaxis

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents our greatest hope to combat the devastating coronavirus disease 2019 (COVID-19) pandemic. Amid ongoing global vaccination efforts, rare cases of severe allergic reactions to COVID-19 mRNA vaccines have received significant attention. Although the exact nature of these reactions may be heterogeneous, various approaches exist to engage with patients, communities, public health departments, primary care providers, and other clinicians in a multidisciplinary approach to advance population health. Whereas it is optimal for patients to receive COVID-19 vaccination as outlined in emergency use authorizations, second-dose deferral of mRNA vaccines may be a consideration within a shared decision-making paradigm of care in select circumstances characterized by high durable first-vaccine–dose protection and significant elevations of vaccine anaphylaxis risk. Still, the durability of protection afforded by a single dose of a COVID-19 mRNA vaccine is uncertain, and alternative approaches to complete vaccination, including precautionary use of a COVID-19 viral vector vaccine, also remain patient-preference–sensitive options. There is an urgent need to define correlates of COVID-19 immunity and the level of longer-term protection afforded by COVID-19 vaccination.

COVID-19 Vaccine-associated Anaphylaxis and Allergic Reactions: Consensus Statements of the KAAACI Urticaria/Angioedema/Anaphylaxis Working Group

In the era of novel coronavirus epidemics, vaccines against coronavirus disease 2019 (COVID-19) have been recognized as the most effective public health interventions to control the pandemic. An adverse event following immunization (AEFI) is defined as any untoward occurrence following immunization, and the majority of AEFIs are caused by protective immune responses stimulated by vaccines. Most of the reported AEFIs are not serious, and many are not immunologically mediated or even reproducible on re-exposure. However, uncommon severe allergic adverse reactions, such as anaphylaxis or other allergic reactions, can occur after vaccinations. Confirmed allergic reactions to vaccines may be caused by residual non-human protein, preservatives, or stabilizers in the vaccine formulation (also known as excipients). There are 2 main potential allergenic/immunogenic excipients in COVID-19 vaccines, polyethylene glycol (PEG) and polysorbate 80. PEG, also known as macrogol, is an ingredient in various laxatives and injectable formulations, such as depot steroids. Polysorbate 80 is present in various medical products, creams, ointments, lotions, and medication tablets. Contraindications to the administration of COVID-19 vaccines include a previous history of severe allergic reactions to the first dose of COVID-19 vaccine or proven hypersensitivity to a vaccine component, such as PEG or polysorbate 80. Anaphylaxis or other allergic reactions following immunization can cause fear and loss of confidence in the safety of vaccines among the public. A better understanding of these events is thought to help alleviate concerns about the current COVID-19 vaccines and provide reassurance to the general population by analyzing the exact incidence of anaphylaxis and potential risk factors. COVID-19 vaccine-associated anaphylaxis could be prevented and managed by risk stratification based on our local and global experience.