Suspected Hypersensitivity Reaction Research Articles

Revaccination outcomes among adolescents and adults with suspected hypersensitivity reactions following COVID-19 vaccination: A Canadian immunization research network study

BackgroundCOVID-19 vaccination has been associated with anaphylaxis and hypersensitivity reactions. Infectious disease physicians and allergists in the Canadian Special Immunization Clinic (SIC) Network developed guidance for evaluating patients with adverse events following immunization (AEFI) including suspected hypersensitivity. This study evaluated management and adverse event recurrence following subsequent COVID-19 vaccinations. MethodsIndividuals aged 12 years and older enrolled at participating SICs before February 28, 2023 who were referred for suspected or diagnosed hypersensitivity reaction following COVID-19 vaccination, or for prevaccination assessment of suspected allergy to a COVID-19 vaccine component were included. De-identified clinical assessments and revaccination data, captured in a centralized database, were analyzed. The Brighton Collaboration case definition (BCCD) for anaphylaxis (2023 version) was applied. ResultsThe analysis included 206 participants from 13 sites: 26 participants referred for pre-vaccination assessment and 180 participants referred for adverse events following COVID-19 vaccination (15/180 [8.3%] with BCCD confirmed anaphylaxis, 84 [46.7%] with immediate hypersensitivity symptoms not meeting BCCD, 33 [18.3%] with other diagnosed hypersensitivity reactions, and 48 [26.7%] participants with a final diagnosis of non-hypersensitivity AEFI). Among participants referred for AEFIs following COVID-19 vaccination, 166/180 (92.2%) were recommended for COVID-19 revaccination after risk assessment, of whom 158/166 (95.2%) were revaccinated (all with a COVID-19 mRNA vaccine). After revaccination, 1/15 (6.7%) participants with prior anaphylaxis, 1/77 (1.3%) with immediate hypersensitivity not meeting criteria for anaphylaxis and 1/24 (4.2%) with other physician diagnosed hypersensitivity developed recurrent AEFI symptoms that met the BCCD for anaphylaxis.All 26 participants referred pre-vaccination, including 9 (34.6%) with history of polyethylene glycol-asparaginase reactions, were vaccinated without occurrence of immediate hypersensitivity symptoms. ConclusionsMost individuals in this national cohort who experienced a hypersensitivity event following COVID-19 vaccination and were referred for specialist review were revaccinated without AEFI recurrence, suggesting that specialist evaluation can facilitate safe revaccination.

The importance of clinical history in the diagnosis of drug hypersensitivity in children.

In case of suspected hypersensitivity reactions (HRs) to drugs, a challenging area for pediatricians is detecting relevant elements in the parent-reported history, in order to reach a definite diagnosis. We analyzed the concordance between the description of the HR and the medical reports documented at the time of the event. Furthermore, we studied any correlation between clinical history variables and the prediction of true allergy. We retrospectively collected 50 charts of children referred to our Allergy Unit, after a previous access to the Emergency Department. We compared the description of the HR at acute phase to the history told by parents. Type and timing of the HR and culprit drug were classified as "known" or "unknown." The diagnosis was confirmed or excluded at the end of the investigations. Logistic regression analysis was performed to find any significant association. The type of the HR was known in 74%, the timing in 28%, and the culprit drug in 98%. We showed that having had a severe HR had an increased odds of remembering the timing; being older >6 years and having had an immediate HR had an increased odds of remembering the type; time to diagnostic was lower in patients whose parents remembered the type of HR. Our paper underlines the importance of an accurate anamnesis at the time of the event. Providing the physicians with a standardized Case Report Form could be a useful tool to simplify the diagnostic work-up and minimize mistakes due to lack of memory.

"Delabeling" by direct provocation testing in children and adolescents with a suspected history of a delayed reaction to β-lactam antibiotics: Consensus paper of Gesellschaft für pädiatrische Allergologie und Umweltmedizin (GPAU), Deutsche Gesellschaft für Allergologie und klinische Immunologie (DGAKI), and Ärzteverband deutscher Allergologen (ÄDA).

Approximately 10% of European children are classified as allergic to drugs. In the majority of these children, no allergy to β-lactam antibiotics (BLA) can be found. In most cases, the exanthema is caused by the infection. The objective of this paper is to describe the causes and consequences of a misdiagnosis of drug allergy. We propose a method for establishing a correct diagnosis in the case of a history of a delayed reaction during treatment with a BLA. For this purpose, a proposal was discussed via e-mail communication, and consensus was reached among the members of the drug allergy working groups of the participating medical societies. The suspicion of a BLA allergy based on the medical history alone can have a negative impact on future antibiotic treatment. Exanthema associated with febrile infections not related to drug administration is a frequent finding in children. This makes it all the more important to be able to recommend a standardized procedure for clarification in children and adolescents with suspected hypersensitivity reactions. The medical history should be the basis on which to diagnose either a drug allergy or another possible differential diagnosis. A mild maculopapular exanthema (MPE) can be an expression of a drug allergy or a nonspecific viral exanthema. Uncomplicated MPE is not associated with significant systemic involvement, and there is no involvement of the mucous membranes or cutaneous blistering. Only a small number of children with uncomplicated MPE show positive skin tests and only ~7 - 16% of suspected BLA diagnoses can be confirmed by provocation tests. Thus, in children with uncomplicated MPE, drug provocation can be performed in an outpatient setting even without prior skin testing. This paper presents a 3-day outpatient direct provocation scheme for BLA delabeling in children with uncomplicated MPE. Many children and adolescents are unnecessarily denied treatment with BLA after an uncomplicated MPE while being treated with a BLA.

Hypersensitivity to glucagon‐like peptide‐1 receptor agonists: A case of delayed urticaria‐like rash to dulaglutide and literature review

AbstractDulaglutide is a glucagon‐like peptide‐1 (GLP‐1) receptor agonist, which stimulates insulin release via activation of GLP‐1 receptors on pancreatic beta cells. We report the case of a 45‐year‐old woman with type 2 diabetes mellitus who started dulaglutide subcutaneously and developed, a few minutes after the fourth administration, a persistent itchy reaction at the injection site, followed, after two more administrations, by a diffuse itchy delayed urticaria‐like rash, healed in 7 days after drug interruption. Skin test performed after 3 months from the event demonstrated the culprit role of the drug. Given the limited evidence in literature, there is currently no standardised protocol for testing patients sensitised to one or more glucagon‐like peptide‐1 receptor agonists. Performing skin tests, especially intradermal tests, is pivotal to confirm the aetiological role of the drug in the suspected hypersensitivity reaction, and possibly to identify an alternative to be proposed before precluding the entire drug class. To the best of our knowledge, this is the first case of systemic hypersensitivity reaction to dulaglutide presenting as a delayed urticaria‐like rash and confirmed by positive skin test.

Management of suspected hypersensitivity reactions to anti-TB drugs.

Management of suspected hypersensitivity reactions to anti-TB drugs.

Allergic emergencies in the prehospital setting: a 5 year retrospective study.

Background. Patients with severe allergic conditions often request support from the prehospital emergency services given the rapid, unexpected and potentially life-threatening nature of the reactions, such as anaphylaxis. Studies regarding prehospital incidents for allergic conditions are scarce. This study aimed to characterize prehospitalar medical requesting assistance due to suspected hypersensitivity reactions (HSR). Methods. Retrospective study of allergic-related requesting assistances between 2017-2022 of a Portuguese emergency dispatch centre - Emergency and Resuscitation Medical Vehicle (VMER), in Coimbra University Hospital. Demographic and clinical variables were analysed, including clinical manifestations, anaphylaxis severity grading, therapeutic interventions, and post-incident allergic work-up. Regarding anaphylactic events, three diagnosis timings were compared: on-site, hospital emergency department and Investigator-diagnosis based on data reviewed. Results. Out of 12689 VMER requesting assistances, 210 (1.7%) were classified as suspected HSR reactions. After on-site medical evaluation, 127 (60.5%) cases maintained the HSR classification (median age 53 years; 56% males) and the main diagnoses included HSR to Hymenoptera venom (29.9%), food allergy (29.1%), and pharmaceutical drugs (25.5%). Anaphylaxis was assumed on-site in 44 (34.7%) cases, in the hospital emergency department in 53 cases (41.7%) and by investigators in 76 (59.8%) cases. Regarding management, epinephrine was administered on-site in 50 cases (39.4%). Conclusions. The main reason for prehospital requesting assistance was HSR to Hymenoptera venom. A high proportion of incidents met the criteria for anaphylaxis and despite the inherent difficulties of the prehospital setting, many of the on-site diagnoses agreed with the criteria. Regarding management, epinephrine was underused in this setting. Referral to specialized consultation is crucial for the management of prehospital incidents.

Polyethylene Glycol and Polysorbate 80 Skin Tests in the Context of an Allergic Risk Assessment for Hypersensitivity Reactions to Anti-SARS-CoV-2 mRNA Vaccines.

Concern has arisen about hypersensitivity reactions in patients with allergic reactions to drugs containing polyethylene glycol (PEG) or polysorbate 80 (PS80), excipients of currently available anti-SARS-CoV-2 mRNA vaccines. However, the actual utility of PEG and PS80 skin allergy testing is currently still debated. We retrospectively analyzed all cases of patients on whom we performed allergometric skin tests for PEG and PS80 in the context of a pre-vaccination screening (for patients with multiple hypersensitivity reactions to drugs for which these excipients were among the suspected agents) or following suspected hypersensitivity reactions to anti-SARS-CoV-2 vaccines. A total of 134 tests were performed for PEG and PS80, eight of which produced uninterpretable results (due to dermographism or non-specific reactions). Of the remaining 126 cases (85 pre-vaccinal and 41 post-vaccine reactions), 16 (12.7%) were positive for PEG and/or PS80. Stratifying by clinical indication, there were no statistically significant differences in the proportion of positive tests between patients evaluated in the context of the pre-vaccination screening and those evaluated after a vaccine reaction (10.6% vs. 17.1%, respectively, p = 0.306). Allergometric skin tests for PEG and PS80 in our case series resulted positive in an unexpectedly high proportion of patients, suggesting that testing for allergy to these two excipients should not be ignored in case of reasonable clinical suspicion.

Basophil Activation Test with Different Polyethylene Glycols in Patients with Suspected PEG Hypersensitivity Reactions

Allergic reactions to COVID-19 vaccine components are rare but should be considered. Polyethylene glycol (PEG) is responsible for anaphylaxis in mRNA vaccines. Skin tests have been used in the allergological work-up programs for COVID-19 vaccine evaluation. However, the reproducibility of the skin prick test is time-dependent and the reactivity declines over time. Therefore, we combined the administration of the skin tests with the basophil activation test (BAT) using PEG2000, PEG4000 and DMG-PEG2000, where the BAT was considered positive when the percentage of activated basophils was higher than 6%, 5% and 6.5%, for PEG 4000, PEG2000 and DMG-PEG2000, respectively. To this end, among the subjects that underwent allergy counseling at the Allergy Unit of our Institution during the 2020/2021 vaccination campaign, 13 patients had a suggested medical history of PEG/drug hypersensitivity and were enrolled together with 10 healthy donors. Among the enrolled patients 2 out of 13 tested patients were positive to the skin test. The BAT was negative in terms of the percentages of activated basophils in all analyzed samples, but the stimulation index (SI) was higher than 2.5 in 4 out of 13 patients. These data evidenced that, when the SI is higher than 2.5, even in the absence of positivity to BAT, the BAT to PEG may be a useful tool to be coupled to skin tests to evidence even low-grade reactions.

A SUCCESSFUL DESENSITIZATION TO OFATUMUMAB

<h3>Introduction</h3> For immune thrombocytopenic purpura (ITP) standard adjunctive therapies include corticosteroids, intravenous immune globulin (IVIG), and/or thrombopoietin receptor antagonists (TPO-RA). In cases of refractory ITP, splenectomy, or monoclonal antibodies against the CD20 antigen (anti-CD20) can be considered. Hypersensitivity reactions to anti-CD20 monoclonals have been reported, however there are no prior published protocols for ofatumumab desensitization. We describe a complex patient with refractory ITP with a successful desensitization protocol. <h3>Case Description</h3> A 39-year-old female with history of Neimann Pick Disease type B (NPD-B), multiple sclerosis, and refractory ITP ineligible for splenectomy with failed treatment with IVIG and a TPO-RA. She experienced suspected hypersensitivity reactions to three CD20 antagonists. She had serum sickness after eight infusion cycles of rituximab. She then developed urticaria during her ninth ofatumumab infusion despite a significant pretreatment regimen. Finally, she was given obinutuzumab which was associated with urticarial and angioedema on her first dose. As the patient continued to have significant thrombocytopenia and no other available treatment options, her oncologist referred her to allergy with goal of desensitization to ofatumumab. <h3>Discussion</h3> To our knowledge we describe the first successful desensitization to ofatumumab. Given that there were no established protocols in the literature, we utilized a rituximab-based protocol that required significant adjustments as ofatumumab has complex dosing requirements, including modifications for dose escalation and maximal concentrations based on its pharmacologic properties. This case report adds to the literature by describing a successfully implemented ofatumumab desensitization protocol in a medically complex patient with hypersensitivity to multiple anti-CD20 monoclonal antibodies

EGG ALLERGY AND YELLOW FEVER IMMUNIZATION: A SAFE DESENSITIZATION PLAN

<h3>Introduction</h3> Yellow fever is a viral hemorrhagic disease with a high-mortality rate endemic to tropical regions of South America and sub-Saharan Africa. While the egg-derived yellow fever vaccine (YF-VAX, Sanofi Pasteur, USA) is safe and provides life-long protection, it can pose a challenge for egg-allergic patients living in or traveling to endemic areas. <h3>Case Description</h3> We present the case of a successful desensitization to YF-VAX in a 10-month-old egg-allergic female traveling to Cameroon. The patient developed diffuse urticaria and facial angioedema with ingestion of boiled eggs at 6 months of age. Her egg white and component egg IgE testing was elevated. Skin prick testing (SPT) was positive to eggs and negative for 1:1 dilution of YF-VAX. Intradermal (ID) testing was positive to 1:10 dilution of YF-VAX. The patient successfully underwent a 5-step desensitization protocol. <h3>Discussion</h3> YF-VAX is a safe, effective immunization to prevent yellow fever. YF-VAX desensitization is easily tolerated and should be considered in egg-allergic patients at risk of complications resulting from the disease. While the American Academy of Pediatrics proposes a protocol to guide physicians in the desensitization of patients with suspected hypersensitivity reactions to immunizations, desensitization to YF-VAX in the United States is not a common occurrence as it is only recommended for people traveling to or living in endemic areas. Rutkowski et al. report a 7-step desensitization protocol of 4 egg-allergic patients with positive SPT to YFV. To our knowledge, this is the first reported case of successful YF-VAX desensitization in the United States using a 5-step desensitization protocol.

How to Take a Good Clinical History in Cases of Allergic Reactions to Medications.

The clinical history is the cornerstone of the doctor´s work. When assessing patients consulting for a suspected hypersensitivity reaction to a drug, the details collected in the patient´s clinical history are essential when deciding which tests to perform and for making recommendations about which drugs the patient should avoid and which can be taken. This area is especially important today, since many patients are labeled as allergic to drugs, especially penicillins, without this being the case. This article reviews the importance of the clinical history in a patient with a hypersensitivity reaction to a drug and considers which data should be collected. Likewise, a record-based model is proposed to help standardize the clinical history.

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

BackgroundOne 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.MethodsDescriptive 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.ResultsSixteen 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.ConclusionsThanks 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.

Risk Factors for Immediate-Type Local Anesthetic Hypersensitivity Reactions in Pediatric Patients: A Retrospective Case-Control Study.

BackgroundLocal anesthetics (LA) are relatively safe and rarely cause immediate hypersensitivity reactions. The data on immediate LA hypersensitivity and its risk factors in children are limited.AimTo evaluate risk factors of immediate LA hypersensitivity.MethodsThe retrospective case-controlled study included 17 patients with confirmed immediate LA hypersensitivity. For each patient, three age- and gender-matched control subjects were included in the study. LA hypersensitivity was excluded by skin tests and subcutaneous drug provocation tests in all control subjects.ResultsThe most common allergic assessment in the patient/control group was for lidocaine (n=5; 29.4%, vs n=23; 45.1%). Suspected LA hypersensitivity reactions were found to be associated with cutaneous manifestations in 14 (82.4%) patients and in 7 (13.7%) of the controls. A history of exposure to local anesthetics twice or more was present in 11 (64.7%) patients vs 6 (11.8%) controls. In conditional regression analysis, repeated LA exposure (≥2) and cutaneous findings were determined as significant risk factors (Odds Ratio [OR]:5.7; 95% Confidence Interval [CI]:1.2–27.1; P=0.029 and (OR:17.3; 95% CI:3.6–82.5; P<0.001, respectively).ConclusionCutaneous manifestations and a history of LA exposure twice or more were predictive factors for LA allergy confirmed by skin test in children.

Characterization of hypersensitivity reactions to polysulfone hemodialysis membranes

BackgroundIn recent years, cases have been reported in which unexpected systemic hypersensitivity reactions occurred in patients dialyzed with polysulfone- or polyethersulfone-biocompatible membranes in the absence of other risk factors. The pathomechanisms involved in these reactions are largely unknown. ObjectiveTo characterize hypersensitivity reactions to polysulfone hemodialysis using clinical and laboratory data and to identify biomarkers suitable for endotype identification and diagnosis. MethodsWe prospectively collected data from 29 patients with suspected hypersensitivity reactions to polysulfone hemodialysis membranes. Clinical laboratory parameters such as tryptase, blood cell counts, and complement levels were recorded. Acute samples were obtained from 18 cases for the ex vivo assessment of basophil activation by flow cytometry analysis of CD63, CD203, and FcεRI cell membrane expression. Serum cytokines and anaphylatoxin concentrations were evaluated in 16 cases by Luminex and cytometric bead array analysis. ResultsTryptase was elevated during the acute reaction in 4 cases. Evidence of basophil activation was obtained in 10 patients. Complement activation was found in only 2 cases. However, C5a serum levels tended to increase during the acute reaction in those patients with hypoxemia. Significantly higher serum levels of interleukin-6 were observed during the acute reactions to polysulfone hemodialysis (P = .0103). ConclusionBased on biomarker analysis, various endotypes were identified, including type I-like (with the involvement of mast cells or basophils), complement, and cytokine (interleukin-6) release-related reactions, with some patients showing mixed reactions. Further research is needed to unravel the exact mechanisms involved in the activation of these cellular and molecular pathways.

Practical management of suspected hypersensitivity reactions to anti-tuberculosis drugs.

Tuberculosis (TB) is the commonest cause of death by a single infectious agent globally and ranks amongst the top ten causes of global mortality. The incidence of TB is highest in Low-Middle Income countries (LMICs). Prompt institution of, and compliance with, therapy are cornerstones for a favourable outcome in TB and to mitigate the risk of multiple drug resistant (MDR)-TB, which is challenging to treat. There is some evidence that adverse drug reactions (ADRs) and hypersensitivity reactions (HSRs) to anti-TB drugs occur in over 60% and 3%-4% of patients respectively. Both ADRs and HSRs represent significant barriers to treatment adherence and are recognised risk factors for MDR-TB. HSRs to anti-TB drugs are usually cutaneous and benign, occur within few weeks after commencement of therapy and are likely to be T-cell mediated. Severe and systemic T-cell mediated HSRs and IgE mediated anaphylaxis to anti-TB drugs are relatively rare, but important to recognise and treat promptly. T-cell-mediated HSRs are more frequent amongst patients with co-existing HIV infection. Some patients develop multiple sensitisation to anti-TB drugs. Whilst skin tests, patch tests and in vitro diagnostics have been used in the investigation of HSRs to anti-TB drugs, their predictive value is not established, they are onerous, require specialist input of an allergist and are resource-dependent. This is compounded by the global, unmet demand for allergy specialists, particularly in low-income countries (LICs)/LMICs and now the challenging circumstances of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. This narrative review provides a critical analysis of the limited published evidence on this topic and proposes a cautious and pragmatic approach to optimise and standardise the management of HSRs to anti-TB drugs. This includes clinical risk stratification and a dual strategy involving sequential re-challenge and rapid drug desensitisation. Furthermore, a concerted international effort is needed to generate real-time data on ADRs, HSRs, safety and clinical outcomes of these interventions.

A Prospective Study of Costs Associated With the Evaluation of β-Lactam Allergy in Children

To evaluate the cost of elective evaluation of β-lactam drug allergies in children.In this study, researchers included any children, up to the age of 14 years, with a suspected hypersensitivity reaction to β-lactam antibiotics who were seen in the outpatient allergy clinic at the University Hospital of Salamanca, Spain. No testing was done on patients with a history of a nonimmediate severe cutaneous reaction.This study was a prospective, observational study performed from June 2017 to May 2018. Testing included skin prick, intradermal tests, and oral challenges. Costs were broken down into direct health care costs, direct non–health care costs, and indirect non–health care costs. Direct health care costs were calculated on the basis of the number of health care visits and testing performed. Direct non–health care costs included transportation costs for families, and indirect non–health care costs were estimated on the basis of missed work for visit appointments.A total of 40 children met inclusion criteria during the year long study (median age: 4 years; range: 0–13 years). Only 3 patients (7.5%) were diagnosed with β-lactam allergy on the basis of positive intradermal skin testing to amoxicillin. A median of 3 office visits per patient were required for evaluation and diagnosis. The mean total cost per patient for evaluation of β-lactam allergy was $308.11 (range: $116.44–$835.36), with a mean direct health care cost of $125.95 per patient, mean direct non–health care cost of $22.55 per patient, and mean indirect non–health care cost of $159.61 per patient.The cost of elective evaluation of β-lactam allergy in pediatric patients is relatively inexpensive, with a mean total cost of $308.11 per patient.Previous studies have revealed that the majority of children labeled with β-lactam allergy do not have true drug allergy, and avoidance of β-lactam antibiotics is associated with increased antimicrobial resistance and use of more expensive antibiotics. This study reveals that outpatient evaluation of β-lactam allergies is relatively inexpensive and may reduce long-term health care costs. Of note, this study was done in Spain, but the authors point out that the total cost of evaluation of β-lactam allergy was similar to that of other studies done with adults in the United States.

Nonirritant concentrations and performance of ceftaroline skin tests in patients with an immediate β-lactam hypersensitivity

In a multicentric European survey,1 cephalosporins were responsible for 10% to 40% of β-lactam hypersensitivity reactions. Adverse reactions to ceftaroline, a broad-spectrum, fifth-generation parenteral cephalosporin, were reported in 10% to 20% of inpatients, a fifth of which were suspected hypersensitivity reactions.2 Establishing nonirritant concentrations (NICs) for skin tests (STs) is critical to ascertain the optimal balance of sensitivity and specificity, improve antibiotic stewardship for the patient, and reduce the costs of health systems.

Revaccination following suspected vaccine-triggered hypersensitivity reactions: experience of a tertiary care centre.

Suspected hypersensitivity reactions (HRs) associated with vaccines are frequently reported, but confirmed cases of vaccine-triggered HRs are rare. Suspected HRs should be distinguished from actual HRs. The aims of this study are to identify the rate of actual vaccine-triggered hypersensitivity in patients who were referred to the paediatric allergy clinic due to a suspected HR and to explore the rate of revaccination in a real clinical setting. A retrospective study was performed with a group of preschool children who were evaluated by skin and/or provocation tests (PTs) for the suspected HRs following vaccination. A total of 26 paediatric patients (61.5% male; median age 9 months) with a previous history of suspected vaccine-triggered HR were included. In this group, 69.2% and 38.5% of the patients had a pre-existing atopic disease and an immediate reaction (emerging <1 hour after vaccine administration), respectively. Skin rash was the most frequent clinical presentation (96.1%). Vaccine-triggered anaphylaxis was reported in six patients (23.1%). Measles-mumps-rubella was the most frequently suspected vaccine causing HRs. The skin test positivity with the suspected vaccine was 4%, whereas PTs revealed no reaction after reimmunisation in 76.9% (20/26) of the study participants tested. Most incidents of skin rashes after immunisation are not suggestive of actual HRs. The results in the current study showed that the majority of the patients presenting with suspected HRs tolerated revaccination, including those with a previous history of suspected anaphylaxis. Revaccination of these patients is safe with adequate precautions. It is absolutely essential to be equipped for the management of anaphylaxis.

Outcome of drug provocation testing in children with suspected beta-lactam hypersensitivity.

BackgroundSuspicion of beta-lactam (BL) hypersensitivity is often based on parental report. Evaluation is important as incorrect labelling has clinical consequence.ObjectiveTo describe the outcomes of drug provocation test (DPT) in children with suspected hypersensitivity.MethodsA retrospective study of patients who completed BL DPT from 1 August 2016 to 31 December 2017 at a paediatric allergy centre in Singapore. Suspected hypersensitivity reactions were classified as immediate (onset ≤1 hour) or delayed (onset > 1 hour). Patients with immediate reactions underwent skin prick test (SPT) followed by DPT if SPT was negative. Patients with delayed reactions underwent DPT directly.ResultsWe identified 120 children who reported 121 suspected hypersensitivity reactions. The median age at reaction was 2.0 years (interquartile range [IQR], 1.0–5.0 years) and the median age at DPT was 7.4 years (IQR, 4.2–11.1 years). The timing of suspected hypersensitivity reaction was immediate in 21% (25 of 121), delayed in 66% (80 of 121), and uncertain in 13% (16 of 121). Commonly implicated drugs were amoxicillin in 45% (54 of 121), amoxicillin-clavulanate in 37% (45 of 121), and cephalexin in 8% (10 of 121). Commonly reported symptoms were maculopapular rash 44% (53 of 121), urticaria 34% (41 of 121), and angioedema 22% (27 of 121). All SPTs (n = 26) were negative. There were 118 diagnostic DPTs to index drug and 3 DPTs to alternative drug. A negative challenge result was obtained in 93% (110 of 118) of diagnostic DPTs: 92% (96 of 104) and 100% (14 of 14) of DPTs to penicillin group and cephalosporins respectively. All challenge reactions were mild.ConclusionOur study supports the opinion that prior skin tests may not be necessary for children who report nonsevere reactions and directly performing diagnostic DPT is a safe approach in the evaluation of suspected childhood BL hypersensitivity.

Canine acute eosinophilic dermatitis with oedema (Wells-like syndrome) associated with T-cell multicentric lymphoma

A nine-year-old female neutered Boxer in clinical remission from T-cell multicentric lymphoma was presented for further investigation of multiple, non-painful, non-pruritic, oedematous, erythematous, serpiginous plaques. On examination, a very mild...