Anaphylaxis as an adverse event following immunisation

Development of Interoperable Computable Phenotype Algorithms for Adverse Events of Special Interest to Be Used for Biologics Safety Surveillance: Validation Study

BACKGROUND

Adverse events associated with vaccination have been evaluated by epidemiological studies and more recently have gained additional attention with the emergency use authorization of several COVID-19 vaccines. As part of its responsibility to conduct postmarket surveillance, the US Food and Drug Administration continues to monitor several adverse events of special interest (AESIs) to ensure vaccine safety, including for COVID-19.

OBJECTIVE

This study is part of the Biologics Effectiveness and Safety Initiative, which aims to improve the Food and Drug Administration's postmarket surveillance capabilities while minimizing public burden. This study aimed to enhance active surveillance efforts through a rules-based, computable phenotype algorithm to identify 5 AESIs being monitored by the Center for Disease Control and Prevention for COVID-19 or other vaccines: anaphylaxis, Guillain-Barré syndrome, myocarditis/pericarditis, thrombosis with thrombocytopenia syndrome, and febrile seizure. This study examined whether these phenotypes have sufficiently high positive predictive value (PPV) to ensure that the cases selected for surveillance are reasonably likely to be a postbiologic adverse event. This allows patient privacy, and security concerns for the data sharing of patients who had nonadverse events can be properly accounted for when evaluating the cost-benefit aspect of our approach.

METHODS

AESI phenotype algorithms were developed to apply to electronic health record data at health provider organizations across the country by querying for standard and interoperable codes. The codes queried in the rules represent symptoms, diagnoses, or treatments of the AESI sourced from published case definitions and input from clinicians. To validate the performance of the algorithms, we applied them to electronic health record data from a US academic health system and provided a sample of cases for clinicians to evaluate. Performance was assessed using PPV.

RESULTS

With a PPV of 93.3%, our anaphylaxis algorithm performed the best. The PPVs for our febrile seizure, myocarditis/pericarditis, thrombocytopenia syndrome, and Guillain-Barré syndrome algorithms were 89%, 83.5%, 70.2%, and 47.2%, respectively.

CONCLUSIONS

Given our algorithm design and performance, our results support continued research into using interoperable algorithms for widespread AESI postmarket detection.

Accounting for indirect protection in the benefit-risk ratio estimation of rotavirus vaccination in children under the age of 5 years, France, 2018

Background Rotavirus is a major cause of severe gastroenteritis in children worldwide. The disease burden has been substantially reduced in countries where rotavirus vaccines are used. Given the risk of vaccine-induced intussusception, the benefit–risk balance of rotavirus vaccination has been assessed in several countries, however mostly without considering indirect protection effects. Aim We performed a benefit–risk analysis of rotavirus vaccination accounting for indirect protection in France among the 2018 population of children under the age of 5 years. Methods To incorporate indirect protection effects in the benefit formula, we adopted a pseudo-vaccine approach involving mathematical approximation and used a simulation design to provide uncertainty intervals. We derived background incidence distributions from quasi-exhaustive health claim data. We examined different coverage levels and assumptions regarding the waning effects and intussusception case fatality rate. Results With the current vaccination coverage of < 10%, the indirect effectiveness was estimated at 6.4% (+/− 0.4). For each hospitalisation for intussusception, 277.0 (95% uncertainty interval: (165.0–462.1)) hospitalisations for rotavirus gastroenteritis were prevented. Should 90% of infants be vaccinated, indirect effectiveness would reach 57.9% (+/− 3.7) and the benefit–risk ratio would be 192.4 (95% uncertainty interval: 116.4–321.3). At a coverage level of 50%, indirect protection accounted for 27% of the prevented rotavirus gastroenteritis cases. The balance remained in favour of the vaccine even in a scenario with a high assumption for intussusception case fatality. Conclusions These findings contribute to a better assessment of the rotavirus vaccine benefit–risk balance.

Vaccination and anaphylaxis: a forensic perspective

Aim

To review the available literature pertaining to fatalities following vaccine administration and, in particular, cases of vaccine-related fatal anaphylaxis.

Method

The MEDLINE database was systematically searched up to March 2016 to identify all relevant articles pertaining to fatal cases of anaphylaxis following vaccine administration.

Results

Six papers pertaining to fatal anaphylaxis following vaccination were found relevant. Mast cell tryptase and total IgE concentration was assessed exclusively in one case. Laryngeal edema was not detected in any of these cases, whereas eosinophil or mast cell infiltration was observed in lymphoid organs. In one case, immunohistochemical investigations using anti-tryptase antibodies allowed pulmonary mast cells and degranulating mast cells with tryptase-positive material outside to be identified.

Conclusion

In any suspected IgE-mediated fatal anaphylactic cases, biochemical investigations should be systematically performed for forensic purposes. Splenic tissue should be routinely sampled for immunohistochemical investigations in all suspected anaphylaxis-related deaths and mast cell/eosinophil infiltrations should be systematically sought out in the spleen, myocardium, and coronary artery wall. The hypothesis of fatal anaphylaxis following vaccination should be formulated exclusively when circumstantial data, available medical records, laboratory investigations, and autopsy or histology findings converge in a consistent pattern. The reasonable exclusion of alternative causes of death after all postmortem investigations is also imperative in order to establish or rule out a cause-and-effect relationship between vaccine administration and any presumptive temporarily-related death.

A study to enhance medical students' professional decision-making, using teaching interventions on common medications

AIM

To create sustained improvements in medical students' critical thinking skills through short teaching interventions in pharmacology.

METHOD

The ability to make professional decisions was assessed by providing year-4 medical students at a UK medical school with a novel medical scenario (antenatal pertussis vaccination). Forty-seven students in the 2012 cohort acted as a pretest group, answering a questionnaire on this novel scenario. To improve professional decision-making skills, 48 students from the 2013 cohort were introduced to three commonly used medications, through tutor-led 40-min teaching interventions, among six small groups using a structured presentation of evidence-based medicine and ethical considerations. Student members then volunteered to peer-teach on a further three medications. After a gap of 8 weeks, this cohort (post-test group) was assessed for professional decision-making skills using the pretest questionnaire, and differences in the 2-year groups analysed.

RESULTS

Students enjoyed presenting on medications to their peers but had difficulty interpreting studies and discussing ethical dimensions; this was improved by contextualising information via patient scenarios. After 8 weeks, most students did not show enhanced clinical curiosity, a desire to understand evidence, or ethical questioning when presented with a novel medical scenario compared to the previous year group who had not had the intervention. Students expressed a high degree of trust in guidelines and expert tutors and felt that responsibility for their own actions lay with these bodies.

CONCLUSION

Short teaching interventions in pharmacology did not lead to sustained improvements in their critical thinking skills in enhancing professional practice. It appears that students require earlier and more frequent exposure to these skills in their medical training.

Does anaphylaxis masquerade as asthma in children?

Anaphylaxis in children presents most frequently with respiratory features, and concern exists about the potential for diagnostic confusion with acute asthma. 84 cases of asthma requiring intensive care were identified. 11 cases met exclusion criteria, which left 73 cases for analysis using established anaphylaxis diagnostic criteria. 13/73 children (17.8%) were found to have sufficient clinical features for a diagnosis of anaphylaxis to be entertained, with 3/73 cases (4.1%) considered highly likely to be anaphylaxis. This study highlights the potential for diagnostic confusion and demonstrates the need to consider anaphylaxis in all children presenting with severe asthma.

Infant anaphylaxis: the importance of early recognition

Anaphylaxis is an acute severe reaction involving multiple systems that results from a rapid release of inflammatory mediators. Patients with asthma and prior allergic reactions are at risk for anaphylaxis. Infants can present a special challenge, as the hallmark symptoms and signs of anaphylaxis may be mistaken as normal findings. These include drooling, vomiting or diarrhea, scratching, and drowsiness. The clinical manifestations of anaphylaxis are broad, as a result of it being a systemic response to an external agent. Among infants and children, there are often respiratory and cutaneous findings. There also can be subtle signs and symptoms, which can often be missed or the findings misinterpreted as normal for developmental age. The incidence of anaphylaxis has increased globally among children presenting with allergic reactions. Early recognition of the signs and symptoms is crucial to effective diagnosis and treatment. This is particularly true among infants 13 months of age or younger who are nonverbal and may have subtle signs and symptoms of a life-threatening reaction to allergens. The purpose of this article is to highlight the differential clinical presentations of young children with anaphylaxis.

Diagnostic utility of two case definitions for anaphylaxis: a comparison using a retrospective case notes analysis in the UK

Anaphylaxis is a clinical diagnosis with no gold-standard test. Recent case definitions have attempted to provide objective criteria for diagnosis. The aim of this study was to compare the diagnostic concordance of the Brighton Collaboration case definition (the 'Brighton' case definition) to the consensus case definition from the Second Symposium on the Definition and Management of Anaphylaxis (the 'Symposium' definition). The study setting was a hospital-based emergency department in the UK. We identified cases of anaphylaxis by physicians' discharge diagnoses over a 2-year period from 2005 to 2006, and used randomly selected cases of allergic reaction, asthma and urticaria as a control group. Data was extracted by clinicians (who were unaware of the content of either case definition), and the two case definitions were applied by Boolean operators in a Microsoft Excel spreadsheet. Concordance between the case definitions was measured using Cohen's kappa (kappa) statistic. We reviewed 128 sets of notes, with 47 cases of anaphylaxis. Brighton and Symposium definitions had sensitivities of 0.681 and 0.671, respectively, and specificities of 0.790 and 0.704, respectively. A discordant result was found in 36/128 cases (28.1%; kappa = 0.414 [95% CI 0.253, 0.574]), which represents a moderate level of agreement between case definitions. The Brighton case definition has a similar diagnostic concordance to the Symposium case definition. It does not seem to over- or underestimate cases and is sufficiently unique that the identification of an allergic trigger does not have to form part of the case definition. This will be important in the recognition of anaphylaxis resulting from the administration of drug and vaccines, where causality should be examined separately from case ascertainment.

Derivation and validation of murine histologic alterations resembling asthma, with two proposed histologic grade parameters

BACKGROUND

The objective was to define murine histologic alterations resembling asthma in a BALB/c OVA model and to suggest grading criteria. Identified were six salient histologic findings in lungs with putative allergic inflammation: 1) bronchoarterial space inflammation; 2) peri-venular inflammation; 3) inflammation about amuscular blood vessels; 4) inter-alveolar space inflammation, not about capillaries; 5) pleural inflammation; and 6) eosinophils within the inflammatory aggregates. An initial study comprised six groups of twelve mice each: 1) stressed, control; 2) stressed, sensitized; 3) stressed, challenged; 4) not physically stressed, control; 5) not physically stressed, sensitized; 6) not physically stressed, challenged. A second study comprised four experimental groups of twenty mice each: 1) stressed, control; 2) stressed, challenged; 3) not physically stressed, control; 4) not physically stressed, challenged. A third study evaluated two grading criteria, 1) the proportion of non-tracheal respiratory passages with inflammatory aggregates and 2) mitoses in the largest two non-tracheal respiratory passages, in five groups of five mice each, evaluated at different times after the last exposure.

RESULTS

The first study suggested the six histological findings might reliably indicate the presence of alterations resembling asthma: whereas 82.4% of mice with a complete response had detectable interleukin (IL)-5, only 3.8% of mice without one did; whereas 77.8% of mice with a complete response were challenged mice, only 6.7% of mice without complete responses were. The second study revealed that the six histological findings provided a definition that was 97.4% sensitive and 100% specific. The third study found that the odds of a bronchial passage's having inflammation declined 1) when mitoses were present (OR = 0.73, 0.60 - 0.90), and 2) with one day increased time (OR = 0.75, 0.65 - 0.86).

CONCLUSION

A definition of murine histologic alterations resembling asthma in the BALB/c OVA mouse was developed and validated. The definition will be of use in experiments involving this model to ensure that all mice said to have undergone an asthmatic attack did indeed reveal allergic pulmonary inflammation. Proposed grading criteria should be further evaluated with additional studies using physiologic measures of attack severity and increased airway resistance.