Risk of anaphylaxis after vaccination in children and adults

Who is (not) vaccinated? A proposal for a comprehensive immunization information system

The role of immunization in public health is crucial, offering widespread protection against infectious diseases and underpinning societal well-being. However, achieving optimal vaccination coverage is impeded by vaccine hesitancy, a significant challenge that necessitates comprehensive strategies to understand and mitigate its effects. We propose the integration of Population Health Management principles with Immunization Information Systems (IISs) to address vaccine hesitancy more effectively. Our approach leverages systematic health determinants analysis to identify at-risk populations and tailor interventions, thereby promoting vaccination coverage and public health responses. We call for the development of an enhanced version of the Italian National Vaccination Registry, which aims to facilitate real-time tracking of individuals' vaccination status while improving data accuracy and interoperability among healthcare systems. This registry is designed to overcome current barriers by ensuring robust data protection, addressing cultural and organizational challenges, and integrating behavioral insights to foster informed public health campaigns. Our proposal aligns with the Italian National Vaccination Prevention Plan 2023-2025 and emphasizes proactive, evidence-based strategies to increase vaccination uptake and contrast the spread of vaccine-preventable diseases. The ultimate goal is to establish a data-driven, ethically sound framework that enhances public health outcomes and addresses the complexities of vaccine hesitancy within the Italian context and beyond.

Nonclinical safety and immunogenicity assessment of a combined DTacP vaccine in animal models

The (diphtheria, tetanus, and pertussis [acellular, component] [DTacP]) vaccine is a combined vaccine designed to prevent three potentially fatal diseases including pertussis, tetanus, and diphtheria in both children and adults. We utilized advanced technology to develop a novel DTacP vaccine that was previously unavailable in China. The nonclinical studies were performed to evaluate the immunogenicity, potential toxicity, and local tolerance of the vaccine in animal models. In the immunogenicity study, three batches of the vaccine were intraperitoneally administered to National Institutes of Health (NIH) mice, resulting in 100% seropositivity for all three batches. Additionally, antibody levels notably increased as the immunization dosage increased. In acute toxicity study, no mortality was observed among the animals during the 14-day observation period, and no abnormalities in clinical signs were reported. Active systemic anaphylaxis assessment in guinea pigs showed no evidence of serious allergic reactions in the vaccine groups. In the repeat-dose toxicity study, where five intramuscular doses were administered every 2 weeks, gross autopsy and histopathological examination revealed no vaccine-related systemic pathological changes in rats, with dose site irritant reactions mostly recovered at the end of recovery period. In conclusion, the vaccine demonstrated good local and systemic tolerance, supporting its clinical development.

Toxicologic Pathology Forum*: mRNA Vaccine Safety-Separating Fact From Fiction

SARS-CoV-2 spread rapidly across the globe, contributing to the death of millions of individuals from 2019 to 2023, and has continued to be a major cause of morbidity and mortality after the pandemic. At the start of the pandemic, no vaccines or anti-viral treatments were available to reduce the burden of disease associated with this virus, as it was a novel SARS coronavirus. Because of the tremendous need, the development of vaccines to protect against COVID-19 was critically important. The flexibility and ease of manufacture of nucleic acid-based vaccines, specifically mRNA-based products, allowed the accelerated development of COVID-19 vaccines. Although mRNA-based vaccines and therapeutics had been in clinical trials for over a decade, there were no licensed mRNA vaccines on the market at the start of the pandemic. The rapid development of mRNA-based COVID-19 vaccines reduced serious complications and death from the virus but also engendered significant public concerns, which continue now, years after emergency-use authorization and subsequent licensure of these vaccines. This article summarizes and addresses some of the safety concerns that continue to be expressed about these vaccines and their underlying technology.

Vaccines and allergy: Back to the right places

Hypersensitivity reactions represent one of the most common causes of hesitancy for adherence to national vaccination programs. The majority of hypersensitivity reactions after vaccination are mild, and anaphylaxis is reported to be rare, although it remains challenging to estimate the frequency attributed to each single vaccine, either because of the lower number of administered doses of less common vaccines, or the administration of simultaneous vaccine in most of the vaccination programs. Although literature remains scattered, international consensus guides clinicians in identifying patients who might need the administration of vaccines in protected environments due to demonstrated hypersensitivity to vaccine components or adjuvants. Here we provide the current guidance on hypersensitivity reactions to vaccines and on vaccination of children with allergy disorders.

Elucidating allergic reaction mechanisms in response to SARS-CoV-2 mRNA vaccination in adults

BACKGROUND

During the COVID-19 pandemic, novel nanoparticle-based mRNA vaccines were developed. A small number of individuals developed allergic reactions to these vaccines although the mechanisms remain undefined.

METHODS

To understand COVID-19 vaccine-mediated allergic reactions, we enrolled 19 participants who developed allergic events within 2 h of vaccination and 13 controls, nonreactors. Using standard hemolysis assays, we demonstrated that sera from allergic participants induced stronger complement activation compared to nonallergic subjects following ex vivo vaccine exposure.

RESULTS

Vaccine-mediated complement activation correlated with anti-polyethelyne glycol (PEG) IgG (but not IgM) levels while anti-PEG IgE was undetectable in all subjects. Depletion of total IgG suppressed complement activation in select individuals. To investigate the effects of vaccine excipients on basophil function, we employed a validated indirect basophil activation test that stratified the allergic populations into high and low responders. Complement C3a and C5a receptor blockade in this system suppressed basophil response, providing strong evidence for complement involvement in vaccine-mediated basophil activation. Single-cell multiome analysis revealed differential expression of genes encoding the cytokine response and Toll-like receptor (TLR) pathways within the monocyte compartment. Differential chromatin accessibility for IL-13 and IL-1B genes was found in allergic and nonallergic participants, suggesting that in vivo, epigenetic modulation of mononuclear phagocyte immunophenotypes determines their subsequent functional responsiveness, contributing to the overall physiologic manifestation of vaccine reactions.

CONCLUSION

These findings provide insights into the mechanisms underlying allergic reactions to COVID-19 mRNA vaccines, which may be used for future vaccine strategies in individuals with prior history of allergies or reactions and reduce vaccine hesitancy.

Ally, adversary, or arbitrator? The context-dependent role of eosinophils in vaccination for respiratory viruses and subsequent breakthrough infections

Eosinophils are a critical type of immune cell and central players in type 2 immunity. Existing literature suggests that eosinophils also can play a role in host antiviral responses, typically type 1 immune events, against multiple respiratory viruses, both directly through release of antiviral mediators and indirectly through activation of other effector cell types. One way to prime host immune responses toward effective antiviral responses is through vaccination, where typically a type 1-skewed immunity is desirable in the context of intracellular pathogens like respiratory viruses. In the realm of breakthrough respiratory viral infection in vaccinated hosts, an event in which virus can still establish productive infection despite preexisting immunity, eosinophils are most prominently known for their link to vaccine-associated enhanced respiratory disease upon natural respiratory syncytial virus infection. This was observed in a pediatric cohort during the 1960s following vaccination with formalin-inactivated respiratory syncytial virus. More recent research has unveiled additional roles of the eosinophil in respiratory viral infection and breakthrough infection. The specific contribution of eosinophils to the quality of vaccine responses, vaccine efficacy, and antiviral responses to infection in vaccinated hosts remains largely unexplored, especially regarding their potential roles in protection. On the basis of current findings, we will speculate upon the suggested function of eosinophils and consider the many potential ways by which eosinophils may exert protective and pathological effects in breakthrough infections. We will also discuss how to balance vaccine efficacy with eosinophil-related risks, as well as the use of eosinophils and their products as potential biomarkers of vaccine efficacy or adverse events.

Current Approaches in Postapproval Vaccine Safety Studies Using Real-World Data: A Systematic Review of Published Literature

PURPOSE

Well-designed observational postmarketing studies using real-world data (RWD) are critical in supporting an evidence base and bolstering public confidence in vaccine safety. This systematic review presents current research methodologies in vaccine safety research in postapproval settings, technological advancements contributing to research resources and capabilities, and their major strengths and limitations.

METHODS

A comprehensive search was conducted using PubMed to identify relevant articles published from January 1, 2019, to December 31, 2022. Eligible studies were summarized overall by study design and other study characteristics (eg, country, vaccine studied, types of data source, and study population). An in-depth review of select studies representative of conventional or new designs, analytical approaches, or data collection methods was conducted to summarize current methods in vaccine safety research.

FINDINGS

Out of 977 articles screened for inclusion, 135 were reviewed. The review shows that recent advancements in scientific methods, digital technology, and analytic approaches have significantly contributed to postapproval vaccine safety studies using RWD. "Near real-time surveillance" using large datasets (via collaborative or distributed databases) has been used to facilitate rapid signal detection that complements passive surveillance. There was increasing appreciation for self-controlled case-only designs (self-controlled case series and self-controlled risk interval) to assess acute-onset safety outcomes, artificial intelligence, and natural language processing to improve outcome accuracy and study timeliness and emerging artificial intelligence-based analysis to capture adverse events from social media platforms.

IMPLICATIONS

Continued development in the area of vaccine safety research methodologies using RWD is warranted. The future of successful vaccine safety research, especially evaluation of rare safety events, is likely to comprise digital technologies including linking RWD networks, machine learning, and advanced analytic methods to generate rapid and robust real-world safety information.

Pharmacovigilance in Vaccines: Importance, Main Aspects, Perspectives, and Challenges-A Narrative Review

Pharmacovigilance plays a central role in safeguarding public health by continuously monitoring the safety of vaccines, being critical in a climate of vaccine hesitancy, where public trust is paramount. Pharmacovigilance strategies employed to gather information on adverse events following immunization (AEFIs) include pre-registration data, media reports, clinical trials, and societal reporting. Early detection of AEFIs during clinical trials is crucial for thorough safety analysis and preventing serious reactions once vaccines are deployed. This review highlights the importance of societal reporting, encompassing contributions from community members, healthcare workers, and pharmaceutical companies. Technological advancements such as quick response (QR) codes can facilitate prompt AEFI reporting. While vaccines are demonstrably safe, the possibility of adverse events necessitates continuous post-marketing surveillance. However, underreporting remains a challenge, underscoring the critical role of public engagement in pharmacovigilance. This narrative review comprehensively examines and synthesizes key aspects of virus vaccine pharmacovigilance, with special considerations for specific population groups. We explore applicable legislation, the spectrum of AEFIs associated with major vaccines, and the unique challenges and perspectives surrounding pharmacovigilance in this domain.

A randomized double-blinded trial to assess recurrence of systemic allergic reactions following COVID-19 mRNA vaccination

BACKGROUND

Systemic allergic reactions (sARs) following coronavirus disease 2019 (COVID-19) mRNA vaccines were initially reported at a higher rate than after traditional vaccines.

OBJECTIVE

We aimed to evaluate the safety of revaccination in these individuals and to interrogate mechanisms underlying these reactions.

METHODS

In this randomized, double-blinded, phase 2 trial, participants aged 16 to 69 years who previously reported a convincing sAR to their first dose of COVID-19 mRNA vaccine were randomly assigned to receive a second dose of BNT162b2 (Comirnaty) vaccine and placebo on consecutive days in a blinded, 1:1 crossover fashion at the National Institutes of Health. An open-label BNT162b2 booster was offered 5 months later if the second dose did not result in severe sAR. None of the participants received the mRNA-1273 (Spikevax) vaccine during the study. The primary end point was recurrence of sAR following second dose and booster vaccination; exploratory end points included biomarker measurements.

RESULTS

Of 111 screened participants, 18 were randomly assigned to receive study interventions. Eight received BNT162b2 second dose followed by placebo; 8 received placebo followed by BNT162b2 second dose; 2 withdrew before receiving any study intervention. All 16 participants received the booster dose. Following second dose and booster vaccination, sARs recurred in 2 participants (12.5%; 95% CI, 1.6 to 38.3). No sAR occurred after placebo. An anaphylaxis mimic, immunization stress-related response (ISRR), occurred more commonly than sARs following both vaccine and placebo and was associated with higher predose anxiety scores, paresthesias, and distinct vital sign and biomarker changes.

CONCLUSIONS

Our findings support revaccination of individuals who report sARs to COVID-19 mRNA vaccines. Distinct clinical and laboratory features may distinguish sARs from ISRRs.

Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older

BACKGROUND

While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years.

METHODS

A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status.

RESULTS

Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively.

CONCLUSIONS

Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.

Analysis of Allergy and Hypersensitivity Reactions to COVID-19 Vaccines According to the EudraVigilance Database

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic presented a new challenge in modern medicine: the development of vaccines was followed by massive population vaccinations. A few reports on post-vaccination allergic reactions have made patients and medical personnel uneasy as to COVID-19 vaccines' allergic potential. Most of the studies in this area to date have been small, and some that were based on global databases skipped most of the allergic diseases and concentrated only on anaphylaxis. We aimed to analyze the incidence of serious allergic reactions based on the EudraVigilance (EV) database, regardless of the reported symptoms and allergy mechanism.

METHODS

The total number of administrated vaccine doses was extracted on 5 October 2023 from Vaccine Tracker and included all administrations since vaccinations began in the European Economic Area (EEA). Data on serious allergic reactions to COVID-19 vaccines were extracted from the EudraVigilance database with the same time point. The code names of 147 allergic symptoms or diseases were used.

RESULTS

The frequency of serious allergic reactions per 100,000 administered vaccine doses was 1.53 for Comirnaty, 2.16 for Spikevax, 88.6 for Vaxzevria, 2.11 for Janssen, 7.9 for Novavax, 13.3 for VidPrevtyn Beta, and 3.1 for Valneva. The most prevalent reported reactions were edema (0.46) and anaphylaxis (0.40). Only 6% of these reactions were delayed hypersensitivity-oriented.

CONCLUSIONS

The overall frequency of potential serious allergic reactions to COVID-19 is very rare. Therefore, COVID-19 vaccines seem to be safe for human use. The lowest frequency of allergic reaction was observed for Comirnaty and the highest for Vaxzevria.

Vaccine hesitancy in patients presenting to a specialized allergy center: clinical relevant sensitizations, impact on mental health and vaccination rates

Introduction

The COVID vaccination program with new types of vaccinations and early reports of allergic reactions to vaccines led to vaccination hesitancy in patients with allergies. In this study, we aimed to characterize patients who present at an allergy center with specific questions regarding risk assessment to COVID vaccines in comparison to regular allergy center patients.

Methods

A total of 50 patient charts of patients with risk assessment for COVID vaccination (COV group) and 50 regular allergy center patients (ALL group) were assessed for documented allergies, comorbidities, total IgE, and tryptase levels and hospital anxiety and depression score (HADS). Skin prick testing (SPT) with additives of COVID vaccines [polyethylene glycol (PEG), polysorbate] were performed if indicated based on medical history.

Results

Patients who presented for examination prior to a possible COVID vaccination were mostly female (86%) and had more frequently reported allergic reactions to drugs in the past, but only in a minor group (28%) were the reactions qualified as anaphylaxis. The group COV patients scored significantly higher in the HADS for anxiety and depression than the regular group ALL patients. The same trend was observed when data were corrected for gender. It is worth noting that patients without any prior contact to COVID vaccines scored comparable regarding anxiety to patients with prior reaction to COVID vaccinations, but significantly higher in the depression score. In 19 patients (38%) who met the indications for SPT for the suspicious contents PEG and Polysorbate 80, the tests did not show a positive result. Furthermore, 84% of patients underwent the prick test, but only 15% of patients who received consultation alone agreed to vaccination at our center. No vaccination-related event was documented in these patients.

Discussion

In conclusion, vaccination hesitancy was frequently elicited by negative experiences with drugs and putative drug allergies. Female patients predominate in this patient group, and the anxiety and depression scores were significantly elevated. Allergological workup, including SPT, led to a high rate of subsequent vaccinations, whereas a discussion with the patients about risks and individualized advice for vaccination without testing only rarely resulted in documented vaccinations.

What rheumatologists need to know about mRNA vaccines: current status and future of mRNA vaccines in autoimmune inflammatory rheumatic diseases

Messenger RNA (mRNA) vaccines as a novel vaccine platform offer new tools to effectively combat both emerging and existing pathogens which were previously not possible. The 'plug and play' feature of mRNA vaccines enables swift design and production of vaccines targeting complex antigens and rapid incorporation of new vaccine constituents as needed. This feature makes them likely to be adopted for widespread clinical use in the future.Currently approved mRNA vaccines include only those against SARS-CoV-2 virus. These vaccines demonstrate robust immunogenicity and offer substantial protection against severe disease. Numerous mRNA vaccines against viral pathogens are in the early to late phase of development. Several mRNA vaccines for influenza are tested in clinical trials, with some already in phase 3 studies. Other vaccines in the early and late phases of development include those targeting Cytomegalovirus, varicella zoster virus, respiratory syncytial virus and Epstein-Barr virus. Many of these vaccines will likely be indicated for immunosuppressed populations including those with autoimmune inflammatory rheumatic diseases (AIIRD). This review focuses on the mechanism, safety and efficacy of mRNA in general and summarises the status of mRNA vaccines in development for common infectious diseases of particular interest for patients with AIIRD.

Adverse events following immunisation: Prospective cohort study evaluating Australian children presenting to specialist immunisation clinics

OBJECTIVE

Prior experience of an adverse event following immunisation is a known barrier to vaccination. Limited Australian data evaluating adverse event recurrence among children exists to inform clinical decisions. We aimed to assess adverse event following immunisation recurrence among children with prior adverse events and to evaluate if family history increased adverse event risk.

METHODS

A prospective cohort study was conducted from March 3rd until August 18th, 2023. Children ≤ 16 years with prior adverse events following immunisation in themselves or family were recruited from specialist immunisation clinics at two quaternary paediatric hospitals. Adverse event outcomes were collected via surveys administered at presentation, three, and eight days post vaccination, and analysed by key characteristics and potential risk factors.

RESULTS

Forty three of forty nine (43/49, 87.8 %) children enrolled received further vaccines. Of those who completed the follow up surveys, 50.0 % (16/32) reported an adverse event. Recurrence of prior adverse events occurred for 23.3 % (10/43, 95 % CI: 11.8 % - 38.6 %) of the cohort. Two of twelve (2/12, 16.7 %) participants with prior serious adverse events who received further vaccines reported a serious adverse event recurrence. No post review serious adverse events were observed in children with prior non serious adverse events. Neurological conditions were a risk factor for prior (neurological condition 3/3 versus no neurological condition 2/40, p < 0.001) and post review (neurological condition 2/3 versus no neurological condition 0/28, p = 0.006) post vaccination seizures. Family history had no relationship to post review adverse events (family history 5/8 versus no family history 11/23, p = 0.685).

CONCLUSION

Revaccination is safe for the majority of children with a personal or family history of adverse event following immunisation.

Web-based survey investigating cardiovascular complications in hypermobile Ehlers-Danlos syndrome after COVID-19 infection and vaccination

BACKGROUND

Hypermobile Ehlers-Danlos syndrome is a heritable connective tissue disorder associated with generalized joint hypermobility but also other multisystem comorbidities, many of which may be exacerbated during a viral illness or after a vaccination. We sought to determine whether individuals with hypermobile Ehlers Danlos syndrome report an increase in adverse events, including cardiovascular events, after COVID-19 illness or vaccination.

METHODS

A cross-sectional web-based survey was made available from November 22, 2021, through March 15, 2022. 368 respondents primarily from the United States self-reported data including diagnosis. We used a Cox proportional hazards model with time varying indicators for COVID-19 illness or vaccination in the previous 30 days.

RESULTS

We found a significantly increased rate of new abnormal heart rhythms reported in the 30 days following COVID-19 illness. No additional cardiovascular events were reported after COVID-19 illness. 2.5% of respondents with COVID-19 illness were hospitalized. We did not find a statistically significant increased rate of cardiovascular events in the 30 days following any COVID-19 vaccination dose. Post COVID-19 vaccination, 87.2% of hypermobile Ehlers-Danlos syndrome respondents endorsed an expected adverse event (EAE), and 3.1% reported an emergency department visit/hospitalization, of those who received at least one vaccine dose. Events possibly reflecting exacerbation of orthostasis/dysautonomia were common.

CONCLUSION

Respondents did not report an increased rate of any cardiovascular events in the 30 days following COVID-19 vaccination; however, those with hypermobile Ehlers-Danlos syndrome experienced a high rate of expected adverse events after vaccination consistent with a high baseline prevalence of similar symptoms. No cardiovascular events other than new abnormal heart rhythms were reported at any point after a COVID-19 illness.

AE-GPT: Using Large Language Models to extract adverse events from surveillance reports-A use case with influenza vaccine adverse events

Though Vaccines are instrumental in global health, mitigating infectious diseases and pandemic outbreaks, they can occasionally lead to adverse events (AEs). Recently, Large Language Models (LLMs) have shown promise in effectively identifying and cataloging AEs within clinical reports. Utilizing data from the Vaccine Adverse Event Reporting System (VAERS) from 1990 to 2016, this study particularly focuses on AEs to evaluate LLMs' capability for AE extraction. A variety of prevalent LLMs, including GPT-2, GPT-3 variants, GPT-4, and Llama2, were evaluated using Influenza vaccine as a use case. The fine-tuned GPT 3.5 model (AE-GPT) stood out with a 0.704 averaged micro F1 score for strict match and 0.816 for relaxed match. The encouraging performance of the AE-GPT underscores LLMs' potential in processing medical data, indicating a significant stride towards advanced AE detection, thus presumably generalizable to other AE extraction tasks.

Adverse Events Following COVID-19 Vaccination in Adolescents: Insights From Pharmacovigilance Study of VigiBase

BACKGROUND

During coronavirus disease 2019 (COVID-19) pandemic, several COVID-19 vaccines were licensed with fast-track procedures. Although these vaccines have demonstrated high immunogenicity, there has been concerns on the serious adverse events (AEs) following COVID-19 vaccination among adolescents. We aimed to analyze comparative safety of COVID-19 vaccination in adolescents.

METHODS

In this pharmacovigilance study, we performed a disproportionality analysis using VigiBase, the World Health Organization's global individual case safety report (ICSR) database. To compare serious AEs reported following COVID-19 vaccines vs. all other vaccines in adolescents aged 12-17 years, ICSRs following any vaccines on adolescents aged 12-17 years were included, defining cases as reports with the AEs of interest, with all other AEs as non-cases. The AEs of interest were myocarditis/pericarditis, multisystem inflammatory syndrome/Kawasaki disease (MIS/KD), anaphylaxis, Guillain-Barré syndrome (GBS), and immune thrombocytopenia (ITP). We conducted a disproportionality analysis to estimate reporting odds ratio (ROR) with 95% confidence interval (CI) for each AE of interest, adjusted for sex by using logistic regression.

RESULTS

Of 99,735 AE reports after vaccination in adolescents, 80,018 reports were from COVID-19 vaccinated adolescents (52.9% females; 56.3% America). The AEs of interest were predominantly reported as serious AE (76.1%) with mRNA vaccines (99.4%). Generally, higher reporting odds for the AEs were identified following COVID-19 vaccination in adolescents; myocarditis/pericarditis (2,829 reports for the COVID-19 vaccine vs. 35 for all other vaccines, adjusted ROR [aROR], 19.61; 95% CI, 14.05-27.39), and MIS/KD (104 vs. 6, aROR, 4.33; 95% CI, 1.89-9.88). The reporting odds for anaphylaxis (515 vs. 165, aROR, 0.86; 95% CI, 0.72-1.02), GBS (94 vs. 40, aROR, 0.64; 95% CI, 0.44-0.92) and ITP (52 vs. 12, aROR, 1.12; 95% CI, 0.59-2.09) were not significantly higher following COVID-19 vaccination.

CONCLUSION

In this study, there were disproportionate reporting of immune-related AEs following COVID-19 vaccination. While awaiting definitive evidence, there is a need to closely monitor for any signs of immune-related AEs following COVID-19 vaccination among adolescents.

Incidence of anaphylaxis to YF-VAX® yellow fever vaccination: a retrospective evaluation of vaccine adverse event reports 1999-2018

BACKGROUND

The incidence of anaphylaxis after receipt of yellow fever (YF) vaccine is highly variable based upon previously published reports. Anaphylaxis after receiving the YF vaccine has been reported to range from 0 up to 22 per 1 000 000 doses. Our clinical experience suggested increased incidence, which prompted our investigation. We sought to evaluate the current incidence rate of anaphylaxis after receipt of the 17D-204 strain YF-VAX® brand reported in the US.

METHODS

We performed a retrospective review of the Vaccine Adverse Event Reporting System (VAERS) reports of anaphylaxis after receiving the YF-VAX vaccine occurring between 1 October 1999 and 30 September 2018. We utilized the Brighton Collaboration Case Definition and inclusion determination was made by a board-certified allergist. We also obtained the total number of YF-VAX doses distributed across the US during this same time-period and then calculated an updated incidence rate of YF-VAX vaccine-associated anaphylaxis.

RESULTS

We identified 132 potential cases of possible or probable anaphylaxis. Of these, 111 met inclusion criteria: level 1 (n = 51), level 2 (n = 59) and level 3 (n = 1). The manufacturer reported a total distribution of 7 624 160 doses of YF-VAX from 1 October 1999 to 30 September 2018. The calculated incidence rate of YF-VAX vaccine-associated anaphylaxis is estimated at 14.6 events per 1 000 000 doses.

CONCLUSIONS

We conclude the estimated rate of anaphylaxis per VAERS reports is 14.6 events per 1 000 000 doses after YF-VAX vaccination. This is consistent with some previous reports and substantially higher than rates of anaphylaxis after other vaccines.

Global burden of vaccine-associated anaphylaxis and their related vaccines, 1967-2023: A comprehensive analysis of the international pharmacovigilance database

BACKGROUND

Vaccine-associated anaphylaxis is a rare but life-threatening reaction that occurs within minutes to hours of exposure to allergens. As studies utilizing large-scale data to investigate this topic are limited, further research is needed to assess its burden, long-term trends, and associated risk factors so as to gain a comprehensive understanding of vaccine-associated anaphylaxis globally. Therefore, this study aimed to investigate the global burden of vaccine-associated anaphylaxis and related vaccines.

METHOD

This study utilized the World Health Organization International Pharmacovigilance Database, in which reports of vaccine-associated anaphylaxis between 1967 and 2023 were obtained (total reports = 131,255,418). We estimated the global reporting counts, reported odds ratio (ROR), and information component (IC) to identify the relationship between 19 vaccines and associated anaphylaxis in 156 countries and territories.

RESULTS

We identified 31,676 reports of vaccine-associated anaphylaxis among 363,290 reports of all-cause anaphylaxis. The cumulative number of reports on vaccine-associated anaphylaxis has gradually increased over time, with a dramatic increase after 2020, owing to reports of COVID-19 mRNA vaccine-associated anaphylaxis. The typhoid vaccines were associated with the most anaphylactic reports (ROR: 4.35; IC0.25 : 1.86), followed by encephalitis (3.27; 1.45), hepatitis B (2.69; 1.30), cholera (2.65; 0.54), hepatitis A (2.44; 1.12), influenza (2.36; 1.16), inactivated whole-virus COVID-19 (2.21; 1.02), and COVID-19 mRNA vaccines (1.89; 0.79). In terms of age- and sex-specific risks, vaccine-associated anaphylaxis reports develop more frequently in females and at young ages. The Ad5-vectored COVID-19 vaccine anaphylaxis reports were associated with the highest fatality rate (15.0%).

CONCLUSIONS

Although multiple vaccines are associated with various spectra and risks of anaphylaxis, clinicians should recognize the possibility of anaphylaxis occurring with all vaccines, particularly the COVID-19 mRNA and inactivated whole-virus COVID-19 vaccines, and consider the risk factors associated with vaccine anaphylaxis reports. Further studies are warranted to identify better ways of preventing vaccine-associated anaphylaxis.

COVID-19 Vaccine Safety Technical (VaST) Work Group: Enhancing vaccine safety monitoring during the pandemic

During the COVID-19 pandemic, candidate COVID-19 vaccines were being developed for potential use in the United States on an unprecedented, accelerated schedule. It was anticipated that once available, under U.S. Food and Drug Administration (FDA) Emergency Use Authorization (EUA) or FDA approval, COVID-19 vaccines would be broadly used and potentially administered to millions of individuals in a short period of time. Intensive monitoring in the post-EUA/licensure period would be necessary for timely detection and assessment of potential safety concerns. To address this, the Centers for Disease Control and Prevention (CDC) convened an Advisory Committee on Immunization Practices (ACIP) work group focused solely on COVID-19 vaccine safety, consisting of independent vaccine safety experts and representatives from federal agencies - the ACIP COVID-19 Vaccine Safety Technical Work Group (VaST). This report provides an overview of the organization and activities of VaST, summarizes data reviewed as part of the comprehensive effort to monitor vaccine safety during the COVID-19 pandemic, and highlights selected actions taken by CDC, ACIP, and FDA in response to accumulating post-authorization safety data. VaST convened regular meetings over the course of 29 months, from November 2020 through April 2023; through March 2023 FDA issued EUAs for six COVID-19 vaccines from four different manufacturers and subsequently licensed two of these COVID-19 vaccines. The independent vaccine safety experts collaborated with federal agencies to ensure timely assessment of vaccine safety data during this time. VaST worked closely with the ACIP COVID-19 Vaccines Work Group; that work group used safety data and VaST's assessments for benefit-risk assessments and guidance for COVID-19 vaccination policy. Safety topics reviewed by VaST included those identified in safety monitoring systems and other topics of scientific or public interest. VaST provided guidance to CDC's COVID-19 vaccine safety monitoring efforts, provided a forum for review of data from several U.S. government vaccine safety systems, and assured that a diverse group of scientists and clinicians, external to the federal government, promptly reviewed vaccine safety data. In the event of a future pandemic or other biological public health emergency, the VaST model could be used to strengthen vaccine safety monitoring, enhance public confidence, and increase transparency through incorporation of independent, non-government safety experts into the monitoring process, and through strong collaboration among federal and other partners.

Gastrointestinal reflux contributes to laryngopharyngeal symptoms that mimic anaphylaxis: COVID-19 vaccination experience

Background

The sensation of throat closure after vaccination is concerning for anaphylaxis and leads to vaccine hesitancy.

Objectives

We characterized patients who developed laryngopharyngeal symptoms (LPhS) after coronavirus disease 2019 (COVID-19) vaccination and assessed risk factors for these symptoms.

Methods

The study analyzed data from the COVID-19 vaccines adverse reactions registry (December 14, 2020, to June 13, 2022). Outcomes included the incidence of postvaccination LPhS and use of epinephrine. We identified and compared risk factors for COVID-19 postvaccination reactions between subjects with and without LPhS.

Results

A total of 158 subjects were enrolled onto the registry. LPhS were reported in 61 subjects (38.6%), of whom 52 (85.2%) received a subsequent dose. With initial vaccination, the use of epinephrine was higher in subjects with LPhS (20%) compared to those without (6%; P = .0094). Fifty-two subjects (85.2%) with LPhS received a subsequent COVID-19 vaccine dose with milder or no symptoms, and none needed treatment with epinephrine. Those with LPhS were more likely to have a history of drug allergies (P = .02), severe medication allergies (P = .03), gastroesophageal reflux disease (P = .018), and need for antireflux medications (P = .0085) compared to controls.

Conclusions

In our registry, postvaccination LPhS were common. LPhS can mimic anaphylaxis and lead to more frequent use of epinephrine. Gastroesophageal reflux disease was more frequent in these subjects. Patients with subjective throat closure sensation can safely receive subsequent vaccine doses with close observation and reassurance. LPhS are not unique to COVID-19 vaccines. Patient and provider education regarding the role of gastroesophageal reflux disease as a risk factor for LPhS with vaccination can improve vaccine uptake.

Neurological and immunological adverse events after pneumococcal conjugate vaccine in children using national immunization programme registry data

BACKGROUND

Despite the general consensus on the safety of pneumococcal conjugate vaccine (PCV), safety concerns unveiled during post-licensure surveillance need to be addressed. We investigated whether there is a transient increased risk following a three-dose series of pneumococcal conjugate vaccine (PCV) administered at 2, 4 and 6 months of age.

METHODS

This was a population-based cohort study using the Korea immunization registry data linked to nationwide administrative claims data. Self-controlled risk interval analysis was conducted for PCV recipients who had an outcome of interest within pre-defined risk and control intervals between 2018 and 2022. The outcomes were anaphylaxis, asthma, encephalopathy, febrile seizure, Kawasaki disease and thrombocytopenia. We used conditional Poisson regression model to estimate the incidence rate ratios (IRRs) and 95% confidence intervals (CIs) comparing the outcomes in the risk and control intervals.

RESULTS

Of 1 114 096 PCV recipients, 8661 had outcomes either in the risk or control intervals. Their mean age at Dose 1 was 10.0 weeks, 58.3% were boys, and 85.3% received 13-valent PCV. PCV was not associated with an increased risk of any outcomes except for febrile seizure. There were 408 (56.0%) cases of febrile seizure in the risk interval, corresponding to an IRR of 1.27 (95% CI 1.10-1.47).

CONCLUSIONS

It is reassuring to note that there was no increased risk of the potential safety concerns following PCV administration. Despite the transient increased risk of febrile seizure, absolute numbers of cases were small. Febrile seizure is generally self-limiting with a good prognosis, and should not discourage parents or caregivers from vaccinating their children.

Harnessing Nanovaccines for Effective Immunization─A Special Concern on COVID-19: Facts, Fidelity, and Future Prospective

Nanotechnology has emerged as a transformative pathway in vaccine research and delivery. Nanovaccines, encompassing lipid and nonlipid formulations, exhibit considerable advantages over traditional vaccine techniques, including enhanced antigen stability, heightened immunogenicity, targeted distribution, and the potential for codelivery with adjuvants or immune modulators. This review provides a comprehensive overview of the latest advancements and applications of lipid and non-lipid-based nanovaccines in current vaccination strategies for immunization. The review commences by outlining the fundamental concepts underlying lipid and nonlipid nanovaccine design before delving into the diverse components and production processes employed in their development. Subsequently, a comparative analysis of various nanocarriers is presented, elucidating their distinct physicochemical characteristics and impact on the immune response, along with preclinical and clinical studies. The discussion also highlights how nanotechnology enables the possibility of personalized and combined vaccination techniques, facilitating the creation of tailored nanovaccines to meet the individual patient needs. The ethical aspects concerning the use of nanovaccines, as well as potential safety concerns and public perception, are also addressed. The study underscores the gaps and challenges that must be overcome before adopting nanovaccines in clinical practice. This comprehensive analysis offers vital new insights into lipid and nonlipid nanovaccine status. It emphasizes the significance of continuous research, collaboration among interdisciplinary experts, and regulatory measures to fully unlock the potential of nanotechnology in enhancing immunization and ensuring a healthier, more resilient society.

Vaccines in cardiology, an underutilized strategy to reduce the residual cardiovascular risk

Cardiovascular diseases stand as the leading cause of mortality among adults globally. For decades, comprehensive evidence has underscored the correlation between infections, particularly those involving the respiratory system, and an elevated risk of cardiovascular and cerebrovascular events, as well as all-cause mortality. The mechanisms through which infections heighten cardiovascular events are intricate, encompassing immune system activation, systemic inflammation, hypercoagulable states, sympathetic system activation, and increased myocardial oxygen demand. Respiratory infections further contribute hypoxemia to this complex interplay. These mechanisms intertwine, giving rise to endothelial dysfunction, plaque ruptures, myocardial depression, and heart failure. They can either instigate de novo cardiovascular events or exacerbate pre-existing conditions. Compelling evidence supports the safety of influenza, pneumococcal, herpes zoster, COVID-19 and respiratory syncytial virus vaccines in individuals with cardiovascular risk factors or established cardiovascular disease. Notably, the influenza vaccine has demonstrated safety even when administered during the acute phase of a myocardial infarction in individuals undergoing angioplasty. Beyond safety, these vaccinations significantly reduce the incidence of cardiovascular events in individuals with an augmented cardiovascular risk. Nevertheless, vaccination rates remain markedly suboptimal. This manuscript delves into the intricate relationship between infections and cardiovascular events. Additionally, we highlight the role of vaccinations as a tool to mitigate these occurrences and reduce residual cardiovascular risk. Finally, we emphasize the imperative need to optimize vaccination rates among individuals with heart diseases.

The mRNA vaccine, a swift warhead against a moving infectious disease target

INTRODUCTION

The rapid development of mRNA vaccines against SARS-CoV-2 has revolutionized vaccinology, offering hope for swift responses to emerging infectious diseases. Initially met with skepticism, mRNA vaccines have proven effective and safe, reducing vaccine hesitancy amid the evolving COVID-19 pandemic. The COVID-19 pandemic has demonstrated that the time required to modify mRNA vaccines to counter new mutant strains is significantly shorter than the time it takes for pathogens to mutate and generate new variants that can thrive in vaccinated populations. This highlights the notion that mRNA vaccine technology appears to be outpacing viruses in the ongoing evolutionary race.

AREAS COVERED

This review article offers valuable insights into several crucial aspects of mRNA vaccine development and deployment, including the fundamentals of mRNA vaccine design and synthesis, the utilization of delivery systems, considerations regarding vaccine safety, the longevity of the immune response, strategies for modifying the original mRNA vaccine to address emerging mutant strains, as well as addressing vaccine hesitancy and potential approaches to mitigate reluctance.

EXPERT OPINION

Challenges such as stability, storage, manufacturing complexities, production capacity, allergic reactions, long-term effects, accessibility, and misinformation must be addressed. Despite these hurdles, mRNA vaccine technology holds promise for revolutionizing future vaccination strategies.

Assessment of adherence to pre-vaccination precautions and AEFI reporting practices during BCG vaccination in 4 hospitals in Ghana

The BCG vaccine, like all other vaccines, is associated with adverse events following immunization (AEFI). Reducing the incidence of AEFI is crucial in reposing confidence in BCG vaccination and reducing hesitancy associated with the vaccine. This requires safety precautions before and during vaccinations, as well as reporting AEFIs after vaccination. This study assessed the adherence of health-care professionals to pre-vaccination precautions and adverse events following immunization (AEFI) reporting practices during BCG vaccination in four hospitals in Ghana. It is hoped that the findings of the study will serve as a baseline to identify gaps for further studies to generate a stronger evidence for policy formulation aimed at improving BCG vaccine safety in Ghana and other tuberculosis endemic countries. A cross-sectional study design was employed, and Statistical Package for Social Sciences, IBM® SPSS version 25 (SPSS Inc. USA) software was used for analysis. Chi-square and binary logistic regression tests were used to test the association between categorical variables and predictors of adherence to pre-BCG vaccination precautions, respectively, and a p-value of <.05 was considered statistically significant. The AEFIs commonly reported by mothers included abscess, injection site pain, injection site redness, fever, rash, muscle weakness, diarrhea, vomiting, coughing and rhinitis. Ninety-three participants (73.2%) were adherent to pre-BCG vaccination precautions. Ninety-two participants (72.4%) informed mothers to report all AEFIs encountered. Adherence to pre-BCG vaccination precautions and AEFI reporting were generally good; however, there is still room for improvement.

Influenza in Children and Adolescents: Epidemiology, Management, and Prevention

EDUCATION GAP

Influenza is among the most common infectious causes of pediatric emergency department visits and hospitalizations. Clinicians should use evidence-based guidelines to learn how to identify, manage, prevent, and treat influenza cases. Disease caused by influenza virus can be mitigated with appropriate treatment and prevention efforts.

OBJECTIVES After completing this article, readers should be able to:

1. Describe the virology and epidemiology of influenza.

2. List the clinical features and complications of influenza infections.

3. List the benefits and limitations of testing modalities for the diagnosis of influenza.

4. Appropriately apply American Academy of Pediatrics, Infectious Diseases Society of America, and Centers for Disease Control and Prevention (CDC) treatment guidelines for influenza or suspected influenza.

5. Describe the importance of influenza vaccination.

An Update in COVID-19 Vaccine Reactions in 2023: Progress and Understanding

It has been 3 years since the coronavirus disease 2019 (COVID-19) pandemic was initially declared, and 2 years have passed since the first COVID-19 vaccines were introduced. Since then, 13.2 billion COVID-19 vaccine doses have been administered worldwide, largely with multiple doses of messenger RNA vaccines. Although mild local and systemic adverse effects after COVID-19 vaccination are common, serious adverse effects following immunization are rare, particularly when compared with the large number of vaccine doses administered. Immediate and delayed reactions are relatively common and present similarly to allergic and hypersensitivity reactions. Despite this, reactions generally do not commonly recur, cause sequelae, or contraindicate revaccination. In this Clinical Management Review, we provide an updated perspective of COVID-19 vaccine reactions, their spectrum and epidemiology, and recommended approaches to evaluation and management.

Automated measurement of distance-walked as a "sixth vital sign" for detecting infusion reactions during preclinical testing

Infusion reactions are a major risk for advanced therapeutics (e.g., engineered proteins nanoparticles, etc.), which can trigger the complement cascade, anaphylaxis, and other life-threatening immune responses. However, during the early phases of development, it is uncommon to assess for infusion reactions, given the labor involved in measuring multiple physiological parameters in rodents. Therefore, we sought to develop an automated quantification of rodent locomotion to serve as a sensitive screening tool for infusion reactions, with minimal added labor-time for each experiment. Here we present the detailed methods for building a motion tracking cage for mice, requiring ∼$100 of materials, ∼2 h to build and set up completely, and employing freely available software (DeepLabCut). The distance-walked after injection was first shown to have the predicted effects for stimulants (caffeine), sedatives (ketamine), and toxins (lipopolysaccharide). Additionally, the distance-walked more sensitively detected the effects of these compounds than did pulse oximetry-based measurements of the classical vital signs of heart rate, respiratory rate, and blood oxygen saturation. Finally, we examined a nanomedicine formulation that has been in preclinical development, liposomes targeted to the cell adhesion molecule ICAM. While this formulation has been studied across dozens of publications, it has not previously been noted to produce an infusion reaction. However, the automated motion tracking cage showed that ICAM-liposomes markedly reduce the distance-walked, which we confirmed by measuring the other vital signs. Importantly, the motion tracking cage added < 5 min of labor time per 5-mouse condition, while pulse oximetry with a neck cuff (by far the most stable oximetry signal in mice) required ∼ 100 min of labor time. Thus, automated measurement of distance-walked can indeed serve as a "sixth vital sign" for detecting infusion reactions during preclinical testing. Additionally, the device to measure distance-walked is easy and cheap to build and requires negligible labor time for each experiment, enabling distance-walked to be recorded in nearly every infusion experiment.

Updated Considerations for the Immunopharmacological Aspects of the "Talented mRNA Vaccines"

Messenger RNA (mRNA) vaccines belong to a new class of medications, RNA therapeutics, including both coding and non-coding RNAs. The use of mRNA as a therapy is based on the biological role of mRNA itself, namely its translation into a functional protein. The goal of mRNA vaccines is to produce a specific antigen in cells to elicit an immune response that might be prophylactic or therapeutic. The potential of mRNA as vaccine has been envisaged for years but its efficacy has been clearly demonstrated with the approval of COVID-19 vaccines in 2021. Since then, mRNA vaccines have been in the pipeline for diseases that are still untreatable. There are many advantages of mRNA vaccines over traditional vaccines, including easy and cost-effective production, high safety, and high-level antigen expression. However, the nature of mRNA itself and some technical issues pose challenges associated with the vaccines' development and use. Here we review the immunological and pharmacological features of mRNA vaccines by discussing their pharmacokinetics, mechanisms of action, and safety, with a particular attention on the advantages and challenges related to their administration. Furthermore, we present an overview of the areas of application and the clinical trials that utilize a mRNA vaccine as a treatment.

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023

This report compiles and summarizes all published recommendations from CDC’s Advisory Committee on Immunization Practices (ACIP) for use of pneumococcal vaccines in adults aged ≥19 years in the United States. This report also includes updated and new clinical guidance for implementation from CDC

Before 2021, ACIP recommended 23-valent pneumococcal polysaccharide vaccine (PPSV23) alone (up to 2 doses), or both a single dose of 13-valent pneumococcal conjugate vaccine (PCV13) in combination with 1–3 doses of PPSV23 in series (PCV13 followed by PPSV23), for use in U.S. adults depending on age and underlying risk for pneumococcal disease. In 2021, two new pneumococcal conjugate vaccines (PCVs), a 15-valent and a 20-valent PCV (PCV15 and PCV20), were licensed for use in U.S. adults aged ≥18 years by the Food and Drug Administration

ACIP recommendations specify the use of either PCV20 alone or PCV15 in series with PPSV23 for all adults aged ≥65 years and for adults aged 19–64 years with certain underlying medical conditions or other risk factors who have not received a PCV or whose vaccination history is unknown. In addition, ACIP recommends use of either a single dose of PCV20 or ≥1 dose of PPSV23 for adults who have started their pneumococcal vaccine series with PCV13 but have not received all recommended PPSV23 doses. Shared clinical decision-making is recommended regarding use of a supplemental PCV20 dose for adults aged ≥65 years who have completed their recommended vaccine series with both PCV13 and PPSV23

Updated and new clinical guidance for implementation from CDC includes the recommendation for use of PCV15 or PCV20 for adults who have received PPSV23 but have not received any PCV dose. The report also includes clinical guidance for adults who have received 7-valent PCV (PCV7) only and adults who are hematopoietic stem cell transplant recipients

Updated guidance regarding the risk of allergic reactions to COVID-19 vaccines and recommended evaluation and management: A GRADE assessment and international consensus approach

This guidance updates 2021 GRADE (Grading of Recommendations Assessment, Development and Evaluation) recommendations regarding immediate allergic reactions following coronavirus disease 2019 (COVID-19) vaccines and addresses revaccinating individuals with first-dose allergic reactions and allergy testing to determine revaccination outcomes. Recent meta-analyses assessed the incidence of severe allergic reactions to initial COVID-19 vaccination, risk of mRNA-COVID-19 revaccination after an initial reaction, and diagnostic accuracy of COVID-19 vaccine and vaccine excipient testing in predicting reactions. GRADE methods informed rating the certainty of evidence and strength of recommendations. A modified Delphi panel consisting of experts in allergy, anaphylaxis, vaccinology, infectious diseases, emergency medicine, and primary care from Australia, Canada, Europe, Japan, South Africa, the United Kingdom, and the United States formed the recommendations. We recommend vaccination for persons without COVID-19 vaccine excipient allergy and revaccination after a prior immediate allergic reaction. We suggest against >15-minute postvaccination observation. We recommend against mRNA vaccine or excipient skin testing to predict outcomes. We suggest revaccination of persons with an immediate allergic reaction to the mRNA vaccine or excipients be performed by a person with vaccine allergy expertise in a properly equipped setting. We suggest against premedication, split-dosing, or special precautions because of a comorbid allergic history.

Recent Advancement in mRNA Vaccine Development and Applications

Messenger RNA (mRNA) vaccine development for preventive and therapeutic applications has evolved rapidly over the last decade. The mRVNA vaccine has proven therapeutic efficacy in various applications, including infectious disease, immunotherapy, genetic disorders, regenerative medicine, and cancer. Many mRNA vaccines have made it to clinical trials, and a couple have obtained FDA approval. This emerging therapeutic approach has several advantages over conventional methods: safety; efficacy; adaptability; bulk production; and cost-effectiveness. However, it is worth mentioning that the delivery to the target site and in vivo degradation and thermal stability are boundaries that can alter their efficacy and outcomes. In this review, we shed light on different types of mRNA vaccines, their mode of action, and the process to optimize their development and overcome their limitations. We also have explored various delivery systems focusing on the nanoparticle-mediated delivery of the mRNA vaccine. Generally, the delivery system plays a vital role in enhancing mRNA vaccine stability, biocompatibility, and homing to the desired cells and tissues. In addition to their function as a delivery vehicle, they serve as a compartment that shields and protects the mRNA molecules against physical, chemical, and biological activities that can alter their efficiency. Finally, we focused on the future considerations that should be attained for safer and more efficient mRNA application underlining the advantages and disadvantages of the current mRNA vaccines.

Identifying and Managing Those at Risk for Vaccine-Related Allergy and Anaphylaxis

Immediate hypersensitivity reactions to vaccines, the most severe of which is anaphylaxis, are uncommon events occurring in fewer than 1 in a million doses administered. These reactions are infrequently immunoglobulin E-mediated. Because they are unlikely to recur, a reaction to a single dose of a vaccine is rarely a contraindication to redosing. This narrative review article contextualizes the recent knowledge we have gained from the coronavirus 2019 (COVID-19) pandemic rollout of the new mRNA platform with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines within the much broader context of what is known about immediate reactions to other vaccinations of routine and global importance. We focus on what is known about evidence-based approaches to diagnosis and management and what is new in our understanding of mechanisms of immediate vaccine reactions. Specifically, we review the epidemiology of immediate hypersensitivity vaccine reactions, differential diagnosis for immune-mediated and nonimmune reaction clinical phenotypes, including how to recognize immunization stress-related responses. In addition, we highlight what is known about mechanisms and review the rare but important contribution of excipient allergies and specifically when to consider testing for them as well as other key features that contribute to safe evaluation and management.

Comparison of medium-term adverse reactions induced by the first and second dose of mRNA BNT162b2 (Comirnaty, Pfizer-BioNTech) vaccine: a post-marketing Italian study conducted between 1 January and 28 February 2021

OBJECTIVES

On 21 December 2020 the European Commission granted conditional marketing authorisation in the European Union for the anti-COVID-19 mRNA vaccine Bnt162b2 (Comirnaty, Pfizer/BioNTech). The main endpoint of this epidemiological, observational, prospective and monocentric study was to identify the number, types, and severity of adverse events following immunisation that occurred in subjects who had been previously infected with COVID-19, and in those who had not, after vaccination with Comirnaty, and to compare the two groups of subjects looking at events that occurred within a month after the first and the second dose.

METHODS

Data were gathered by a questionnaire. The results included the responses of all healthcare workers (2030) of the IRCCS Sacro Cuore Don Calabria Hospital (Italy) vaccinated between 1st January and 28th February 2021. Adverse effects of the vaccine were reported after the first and the second doses.

RESULTS

There was a statistically significant increase (p<0.001, χ2=35.60) in participants who experienced some side-effects after receiving the first dose of the vaccine and who had previously been infected with the coronavirus, compared with participants who had not previously been infected. 46.76% (136) of the participants who had previously been infected experienced some side-effects after the first dose of vaccine, and 63.23% (184) experienced some side-effects after the second dose, compared with 29.15% (507) after the first dose and 70.79% (1231) after the second dose in those who had not been previously infected. The number of participants who experienced side-effects after the second dose and had previously been infected was significantly lower compared with participants who had not previously been infected (p=0.0094, χ2=6.743).

CONCLUSIONS

Most of the side-effects identified in this trial were also reported by the manufacturer and the US Food and Drug Administration. Active surveillance should always continue to constantly check the vaccine's risk/benefit ratio over time.

Analysis of deaths following yeast-derived hepatitis B vaccination of infants, China, January 2013 to December 2020

In China, adverse events following immunization (AEFI) are reported by the China AEFI Surveillance System (CNAEFIS). Serious AEFI, including deaths, are mandatorily reported and are evaluated for causality by province-or prefecture-level panels of experts. Yeast-derived HepB is the most widely used HepB in China for infants. However, the information about the death of infants caused by HepB is unclear. The CNAEFIS data on deaths following HepB from 2013 to 2020 were used for analyses. Descriptive analysis of epidemiologic characteristics was used to report death cases following HepB. We used administered doses to calculate denominators to estimate the risk of death after vaccination. During 2013-2020, there were 161 deaths following the administration of 173 million doses of HepB, for an overall incidence of 0.9 deaths per million doses. One hundred fifty-seven deaths were categorized as coincidental, and four deaths were accompanied by an abnormal reaction determined to be unrelated to the cause of death. The most common causes of death were neonatal pneumonia and foreign body asphyxia. These data provide reliable evidence on the safety of HepB among infants in China and can enhance public confidence in HepB immunization. To ensure public confidence in infants' HepB vaccination, monitoring and scientifically evaluating AEFI-related deaths of HepB is necessary.

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.

Anaphylatoxin Complement 5a in Pfizer BNT162b2-Induced Immediate-Type Vaccine Hypersensitivity Reactions

The underlying immunological mechanisms of immediate-type hypersensitivity reactions (HSR) to COVID-19 vaccines are poorly understood. We investigate the mechanisms of immediate-type hypersensitivity reactions to the Pfizer BNT162b2 vaccine and the response of antibodies to the polyethylene glycol (PEG)ylated lipid nanoparticle after two doses of vaccination. Sixty-seven participants, median age 35 and 77.3% females who tolerated two doses of the BNT162b2 vaccine (non-reactors), were subjected to various blood-sampling time points. A separate group of vaccine reactors (10 anaphylaxis and 37 anonymised tryptase samples) were recruited for blood sampling. Immunoglobulin (Ig)G, IgM and IgE antibodies to the BNT162b2 vaccine, biomarkers associated with allergic reaction, including tryptase for anaphylaxis, complement 5a(C5a), intercellular adhesion molecule 1 (ICAM-1) for endothelial activation and Interleukin (IL)-4, IL-10, IL-33, tumour necrosis factor (TNF) and monocyte chemoattractant protein (MCP-1), were measured. Basophil activation test (BAT) was performed in BNT162b2-induced anaphylaxis patients by flow cytometry. The majority of patients with immediate-type BNT162b2 vaccine HSR demonstrated raised C5a and Th2-related cytokines but normal tryptase levels during the acute reaction, together with significantly higher levels of IgM antibodies to the BNT162b2 vaccine (IgM 67.2 (median) vs. 23.9 AU/mL, p < 0.001) and ICAM-1 when compared to non-reactor controls. No detectable IgE antibodies to the BNT162b2 vaccine were found in these patients. The basophil activation tests by flow cytometry to the Pfizer vaccine, 1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol (DMG-PEG) and PEG-2000 were negative in four anaphylaxis patients. Acute hypersensitivity reactions post BNT162b2 vaccination suggest pseudo-allergic reactions via the activation of anaphylatoxins C5a and are independent of IgE-mechanisms. Vaccine reactors have significantly higher levels of anti-BNT162b2 IgM although its precise role remains unclear.

Evaluation of association of anti-PEG antibodies with anaphylaxis after mRNA COVID-19 vaccination

BACKGROUND

The mechanism for anaphylaxis following mRNA COVID-19 vaccination has been widely debated; understanding this serious adverse event is important for future vaccines of similar design. A mechanism proposed is type I hypersensitivity (i.e., IgE-mediated mast cell degranulation) to polyethylene glycol (PEG). Using an assay that, uniquely, had been previously assessed in patients with anaphylaxis to PEG, our objective was to compare anti-PEG IgE in serum from mRNA COVID-19 vaccine anaphylaxis case-patients and persons vaccinated without allergic reactions. Secondarily, we compared anti-PEG IgG and IgM to assess alternative mechanisms.

METHODS

Selected anaphylaxis case-patients reported to U.S. Vaccine Adverse Event Reporting System December 14, 2020-March 25, 2021 were invited to provide a serum sample. mRNA COVID-19 vaccine study participants with residual serum and no allergic reaction post-vaccination ("controls") were frequency matched to cases 3:1 on vaccine and dose number, sex and 10-year age category. Anti-PEG IgE was measured using a dual cytometric bead assay (DCBA). Anti-PEG IgG and IgM were measured using two different assays: DCBA and a PEGylated-polystyrene bead assay. Laboratorians were blinded to case/control status.

RESULTS

All 20 case-patients were women; 17 had anaphylaxis after dose 1, 3 after dose 2. Thirteen (65 %) were hospitalized and 7 (35 %) were intubated. Time from vaccination to serum collection was longer for case-patients vs controls (post-dose 1: median 105 vs 21 days). Among Moderna recipients, anti-PEG IgE was detected in 1 of 10 (10 %) case-patients vs 8 of 30 (27 %) controls (p = 0.40); among Pfizer-BioNTech recipients, it was detected in 0 of 10 case-patients (0 %) vs 1 of 30 (3 %) controls (p >n 0.99). Anti-PEG IgE quantitative signals followed this same pattern. Neither anti-PEG IgG nor IgM was associated with case status with both assay formats.

CONCLUSION

Our results support that anti-PEG IgE is not a predominant mechanism for anaphylaxis post-mRNA COVID-19 vaccination.

Vaccine confidence among those living with allergy during the COVID pandemic (ACCORD): A scoping review

Background

Reports of allergic reactions to coronavirus disease 2019 (COVID-19) vaccines, coupled with an "infodemic" of misinformation, carry the potential to undermine confidence in the COVID-19 vaccines. However, no attempts have been made to comprehensively synthesize the literature on how allergic disease and fear of allergic reactions to the vaccines contribute to hesitancy.

Objectives

Our aim was to review the academic and gray literature on COVID-19 vaccine hesitancy and allergic reactions.

Methods

We searched 4 databases (CINAHL, PsycINFO, MEDLINE, and Embase) using a search strategy developed by content and methodologic experts. No restrictions were applied regarding COVID-19 vaccine type, country of study, or patient age. Eligible articles were restricted to 10 languages.

Results

Of the 1385 unique records retrieved from our search, 60 articles (4.3%) were included. Allergic reactions to the COVID-19 vaccine were rare but slightly more common in individuals with a history of allergic disease. A fifth of the studies (13 of 60 [22%]) discussed vaccine hesitancy due to possibility of an allergic reaction. Additionally, the present review identified research on details of vaccine-related anaphylaxis (eg, a mean and median [excluding clinical trial data] of 12.4 and 5 cases per million doses, respectively) and allergic reactions (eg, a mean and median [excluding clinical trial data] of 489 and 528 cases per million doses, respectively).

Conclusion

COVID-19 vaccine acceptance among individuals living with allergy and among those with no history of allergic disease may be affected by fear of an allergic reaction. Despite the low incidence of allergic reactions to the COVID-19 vaccine, fear of such reactions is one of the most commonly cited concerns reported in the literature.

Administration of the Second Dose of mRNA COVID-19 Vaccine to a Woman With Immediate Reaction to the First Dose

Vaccines constitute the most effective public health intervention as they prevent the spread of infectious diseases and reduce disease severity and mortality. Allergic reactions can occur during vaccination. Systemic anaphylaxis is a severe, life-threatening allergic reaction which can rarely occur after vaccination. There is limited data suggesting that the majority of the patients with immediate and potentially allergic reactions after the first dose of coronavirus disease 2019 (COVID-19) can receive the second dose. A 39-year-old woman was admitted to our department after presenting anaphylactic reaction following the first dose of mRNA COVID-19 vaccine (BNT162b2). A few days later, she contacted our department and was admitted for an allergy work-up on mRNA COVID-19 vaccine and its compound polyethylene glycol (PEG). Thereafter, she completed the vaccination procedure having received pretreatment under our guidance. Confirmed allergic reactions to vaccines are customarily attributed to the inactive ingredients, or excipients like PEG and polysorbate. The latest are used to improve water-solubility in vaccines. PEG itself has not been previously used in a vaccine but polysorbate has been identified as a rare cause of allergic reactions to vaccines. It has been reported that the interaction of the immune system with lipidic nanoparticle therapeutics could result in hypersensitivity reactions (HSRs), referred to as complement activation related pseudoallergy (CARPA), which is classified as non-IgE-mediated pseudoallergy caused by the activation of the complement system.

mRNA COVID-19 Vaccine Anaphylaxis: Epidemiology, Risk Factors, and Evaluation

PURPOSE OF REVIEW

The COVID-19 vaccines have proved essential in our defense against the COVID-19 pandemic. However, concerns regarding allergic reactions to the vaccines persist to this day. Herein, we review the data regarding the frequency of allergic reactions to the COVID-19 vaccines, the epidemiology, and the management of patients reporting vaccine allergic reactions.

RECENT FINDINGS

Although initial reports emphasized a high risk of anaphylaxis to the COVID-19 vaccines, more recent data demonstrate similar rates of anaphylaxis to the COVID-19 vaccines as to other vaccines. Alternative explanations for increased rates of apparent allergic reactions are discussed, including the role for stress-related and nocebo responses. COVID-19 vaccines and mRNA vaccine technology are overwhelmingly safe and well-tolerated by most patients. Careful history and case review will enable the discerning physician to safely vaccinate most patients. Rare patients with objective signs and symptoms of anaphylaxis may be candidates for alternatives to vaccination including monoclonal antibodies.

Allergic Reactions to Vaccines in Children: From Constituents to Specific Vaccines

Vaccination is an essential public health measure that helps to reduce the burden of infectious diseases in children. Although vaccines have an excellent safety record and the association of severe allergic reactions is rare, public concerns about vaccine safety can lead to incomplete vaccination coverage in children with or without allergies. Therefore, it is important to understand the mechanisms and implications of allergic reactions to vaccines and define strategies to manage them to provide the safest care for vaccine recipients. In this review, we provide an overview on the types of allergic reactions that can occur after vaccination, including those caused by various vaccine constituents. We also discuss the mechanisms underlying these allergic reactions and the recommended diagnosis and management strategies for children with a history of suspected allergic reactions to vaccines. An improved understanding of allergic reactions to vaccines can aid in the enhancement of the safety and effectiveness of vaccination.

COVID-19 vaccine hesitancy in care home staff: A survey of Liverpool care homes

Uptake of COVID-19 vaccine first doses in UK care homes has been higher among residents compared to staff. We aimed to identify causes of lower COVID-19 vaccine uptake amongst care home staff within Liverpool. An anonymised online survey was distributed to all care home managers, between the 21st and the 29th January 2021. 53 % of 87 care homes responded. The overall COVID-19 vaccination rate was 52.6 % (n = 1119). Reasons, identified by care home managers for staff being unvaccinated included: concerns about lack of vaccine research (37.0 %), staff being off-site during vaccination sessions (36.5 %), pregnancy and fertility concerns (5.6 %), and allergic reactions concerns (3.2 %). Care home managers wanted to tackle vaccine hesitancy through conversations with health professionals, and provision of evidence dispelling vaccine misinformation. Vaccine hesitancy and logistical issues were the main causes for reduced vaccine uptake among care home staff. The former could be addressed by targeted training, and public health communication campaigns to build confidence and acceptance of COVID-19 vaccines.

The conundrum of COVID-19 mRNA vaccine-induced anaphylaxis

Novel messenger RNA (mRNA) vaccines have proven to be effective tools against coronavirus disease 2019, and they have changed the course of the pandemic. However, early reports of mRNA vaccine-induced anaphylaxis resulted in public alarm, contributing toward vaccine hesitancy. Although initial reports were concerning for an unusually high rate of anaphylaxis to the mRNA vaccines, the true incidence is likely comparable with other vaccines. These reactions occurred predominantly in young to middle-aged females, and many had a history of allergies. Although initially thought to be triggered by polyethylene glycol (PEG), lack of reproducibility of these reactions with subsequent dosing and absent PEG sensitization point away from an IgE-mediated PEG allergy in most. PEG skin testing has poor posttest probability and should be reserved for evaluating non-vaccine-related PEG allergy without influencing decisions for subsequent mRNA vaccination. Immunization stress-related response can closely mimic vaccine-induced anaphylaxis and warrants consideration as a potential etiology. Current evidence suggests that many individuals who developed anaphylaxis to the first dose of an mRNA vaccine can likely receive a subsequent dose after careful evaluation. The need to understand these reactions mechanistically remains critical because the mRNA platform is rapidly finding its way into other vaccinations and therapeutics.

Adverse event reports of anaphylaxis after Comirnaty and Vaxzevria COVID-19 vaccinations, Western Australia, 22 February to 30 June 2021

Within the first 4 months of the Western Australian COVID-19 immunisation programme, 49 suspected anaphylaxis cases were reported to the vaccine safety surveillance system. Twelve reports met Brighton Collaboration case definition, corresponding to rates of 15.9 and 17.7 per million doses of Vaxzevria and Comirnaty administered respectively.

A Comprehensive Review of mRNA Vaccines

mRNA vaccines have been demonstrated as a powerful alternative to traditional conventional vaccines because of their high potency, safety and efficacy, capacity for rapid clinical development, and potential for rapid, low-cost manufacturing. These vaccines have progressed from being a mere curiosity to emerging as COVID-19 pandemic vaccine front-runners. The advancements in the field of nanotechnology for developing delivery vehicles for mRNA vaccines are highly significant. In this review we have summarized each and every aspect of the mRNA vaccine. The article describes the mRNA structure, its pharmacological function of immunity induction, lipid nanoparticles (LNPs), and the upstream, downstream, and formulation process of mRNA vaccine manufacturing. Additionally, mRNA vaccines in clinical trials are also described. A deep dive into the future perspectives of mRNA vaccines, such as its freeze-drying, delivery systems, and LNPs targeting antigen-presenting cells and dendritic cells, are also summarized.

Skin Testing and Basophil Activation Testing Is Useful for Assessing Immediate Reactions to Polyethylene Glycol-Containing Vaccines

BACKGROUND

The mechanism of immediate reactions to drugs or vaccines containing polyethylene glycol (PEG) and PEG derivatives is not fully elucidated. It is considered in many instances to be IgE-mediated. Diagnosis and management of PEG allergy is topical, as BNT162b and mRNA-1273 contain PEG (2[PEG-2000]-N), and ChAdOx1-S and NVX-CoV2373 contain polysorbate 80. mRNA vaccines contain PEG 2000, which encapsulates the mRNA to impair its degradation. This PEG MW is specific to mRNA vaccines and is not used in other drugs and vaccines. PEG 2000 allergy is not well studied, as higher PEG molecular weights are implicated in most of the PEG allergy published in the literature.

METHODS

We performed a literature review on PEG allergy and sought to evaluate the safety and effectiveness of our protocol for assessment of PEG 2000 and polysorbate 80 reactions in an outpatient clinic setting. All patients referred to our drug allergy service between 1 July 2021 and 31 December 2021 with suspected immediate allergy to PEG or its derivatives were eligible for the study. Skin testing (ST) and basophil activation testing (BAT) were performed for all patients to multiple PEG molecular weights (MWs).

RESULTS

We reviewed twenty patients during the study period. Five patients were allergic. Fifteen patients had a masquerade of allergy and were enrolled as control patients. PEG 2000, polysorbate 80, BNT162b, and ChAdOx1-S had excellent performance characteristics on skin testing. BAT showed high specificity for all vaccines and PEG MWs.

DISCUSSION

In our small study, we found ST and BAT to add useful information, particularly for PEG 2000 allergy. Further study of our protocol in larger patient cohorts will provide more information on its performance characteristics and usefulness.