Algorithm to assess causality after individual adverse events following immunizations

The potential association between herpes zoster and COVID-19 vaccination

Objective

Little is known about the dermatological manifestations associated with COVID-19 vaccines. The aim of the study was to determine how many cases of herpes zoster (HZ) occurred after COVID-19 vaccination and to see if there was a possible link.

Methods

A retrospective cohort study was performed by archive scan between 2016 and 2020, and between January 2021 and January 2022. Patients diagnosed with HZ were enrolled and their demographic and medical history including age, sex, previous systemic disease, history of COVID-19 vaccination prior to HZ symptom onset, COVID-19 vaccine type as mRNA or inactive, time to HZ onset after vaccination, and number of COVID-19 vaccines before HZ symptom onset were recorded.

Results

The average annual number of HZ cases from 2016 to 2020 was 271, but the number of HZ cases in 2021 was 338, reflecting an increase. The number of HZ patients with a known history of COVID-19 vaccination in 2021 was 117 and their mean age was 57.6 ± 14.2 years. Females were 59.8% (n = 70) and 28.2% (n = 33) had chronic diseases. A positive history of COVID-19 vaccination was present in 35.9% (n = 42) of HZ patients, 11.1% (n = 13) had received mRNA vaccines and 24.8% (n = 29) had received inactive COVID-19 vaccine. Mean time to HZ after COVID-19 vaccination was 24.6 ± 16.3 days.

Conclusion

An important finding of this study is the high rate (35.9%) of COVID-19 vaccination among people diagnosed with HZ. As COVID-19 vaccination may be associated with reactivation of varicella zoster virus, the vaccination history should be obtained in HZ patients.

Observational Study of Patients Hospitalized With Neurologic Events After SARS-CoV-2 Vaccination, December 2020-June 2021

Background and Objectives

The global spread of the COVID-19 pandemic accelerated the vaccine development time line, regulatory approval, and widespread implementation in the population underscoring the importance of postauthorization/postlicensure vaccine safety surveillance. To monitor for vaccine-related adverse events, we prospectively identified patients hospitalized for prespecified neurologic conditions who received mRNA or adenovirus COVID-19 vaccines and assessed cases for potential risk factors and alternative etiologies of the adverse event.

Methods

We identified prespecified neurologic conditions in hospitalized individuals within 6 weeks of receipt of a dose of any COVID-19 vaccination between December 11, 2020, and June 22, 2021 (Columbia University Irving Medical Center/New York Presbyterian Hospital, New York City, New York). Clinical data from electronic medical records in these vaccinated patients were reviewed for assessment of contributing risk factors and etiologies for these neurologic conditions by use of a published algorithm.

Results

Among 3,830 individuals screened for COVID-19 vaccination status and neurologic conditions, 138 (3.6%) cases were included in this study (126 after mRNA and 6 after Janssen vaccines). The 4 most prevalent neurologic syndromes included ischemic stroke (52, 37.7%), encephalopathy (45, 32.6%), seizure (22, 15.9%), and intracranial hemorrhage (ICH) (13, 9.4%). All 138 cases (100%) had 1 or more risk factors and/or evidence for established causes. Metabolic derangement was the most common etiology for seizures (24, 53.3%) and encephalopathy (5, 22.7%) while hypertension was the most significant risk factor in ischemic stroke (45, 86.5%) and ICH cases (4, 30.8%).

Discussion

All cases in this study were determined to have at least 1 risk factor and/or known etiology accounting for their neurologic syndromes. Our comprehensive clinical review of these cases supports the safety of mRNA COVID-19 vaccines.

Self-reported side effects following COVID-19 vaccination in athletes: A retrospective study

Billions of coronavirus disease 19 (COVID-19) vaccines have been administered worldwide. However, limited data on side effects have been reported in athletes. This study aimed to describe the incidence of side effects following COVID-19 vaccination in athletes and to identify the factors associated with the main side effects in this population. Information on COVID-19 vaccination, side effects, and overall symptom duration was retrospectively collected from recreational and competitive athletes. A total of 460 participants were included in this study. Fever and arm pain were more frequently reported after the first-dose vaccination, 9.6% vs 4.6%, p = .007 and 81.3% vs 24.9%, p ≤ .001. Myalgia was more common after the second-dose vaccination, 0.65% vs. 7.1% p ≤ .001. Males were more likely to present with arm pain after the first and second vaccinations. Those with SARS-CoV-2 infection before vaccination were less likely to present with arm pain after the first dose of vaccination (OR: 0.162, p ≤ .001) and more likely to present with fever after the second dose of vaccination (OR: 3.442, p = .046). First-dose vaccination with the BNT162b2 vaccine compared to other brands was characterized by lower odds of fever (OR: 0.394, p = .017). Our results indicated mild adverse effects and a short duration of symptoms in athletes following COVID-19 vaccination.

Assessing vaccine safety during a pandemic: Recent experience and lessons learned for the future

During the roll out of vaccines during a pandemic, questions regarding vaccine safety often arise. This was surely true during the SARS-CoV-2 pandemic. Different tools and capabilities exist during the pre-authorization phase and post introduction each with its strengths and limitations. Here we review the various tools and their strengths and limitations and discuss what functioned well in high income settings and the limitations that unequal vaccine safety pharmacovigilance capacity imposed upon middle and low income countries.

Considerations for unblinding individual study participants during vaccine trials

Premature unblinding of individual participants is rarely reported in publications, but such unblinding can disrupt vaccine trials by causing worry and drop-out of other participants or "pseudo unblinding," in which participants or investigators over-interpret certain symptoms as being related to receiving an investigational product. This review summarizes appropriate reasons for unblinding in vaccine trials. Regulatory guidance could be improved by distinguishing guidance for vaccine trials from drug trials, with the recognition that unblinding individual participants in vaccine studies is rarely needed for management of adverse events following immunization.

A narrative review of vaccine pharmacovigilance during mass vaccination campaigns: Focus on myocarditis and pericarditis after COVID-19 mRNA vaccination

Vaccines have had a tremendous impact on reducing the burden of infectious diseases; however, they have the potential to cause adverse events following immunization (AEFIs). Prelicensure clinical trials are limited in their ability to detect rare AEFIs that may occur in less than one per thousand individuals. While postmarketing surveillance systems have shown COVID-19 mRNA vaccines to be safe, they led to the identification of rare cases of myocarditis and pericarditis after COVID-19 vaccination that were not initially detected in clinical trials. In this narrative review, we highlight concepts of vaccine pharmacovigilance during mass vaccination campaigns and compare the approaches used in the context of myocarditis and pericarditis following COVID-19 vaccination to historical examples. We describe mechanisms of passive and active surveillance, their strengths and limitations, and how they interacted to identify and characterize the safety signal of myocarditis and pericarditis after COVID-19 mRNA vaccination. Articles were synthesized from a PubMed search using relevant keywords for articles published on vaccine surveillance systems and myocarditis and pericarditis after COVID-19 vaccination, as well as the authors' collections of relevant publications and grey literature reports. The global experience around the identification and monitoring of myocarditis and pericarditis after COVID-19 mRNA vaccination has provided important lessons for vaccine safety surveillance and highlighted its importance in maintaining public trust in mass vaccination programmes in a pandemic context.

Applying lessons learned from nanomedicines to understand rare hypersensitivity reactions to mRNA-based SARS-CoV-2 vaccines

After over a billion of vaccinations with messenger RNA-lipid nanoparticle (mRNA-LNP) based SARS-CoV-2 vaccines, anaphylaxis and other manifestations of hypersensitivity can be considered as very rare adverse events. Although current recommendations include avoiding a second dose in those with first-dose anaphylaxis, the underlying mechanisms are unknown; therefore, the risk of a future reaction cannot be predicted. Given how important new mRNA constructs will be to address the emergence of new viral variants and viruses, there is an urgent need for clinical approaches that would allow a safe repeated immunization of high-risk individuals and for reliable predictive tools of adverse reactions to mRNA vaccines. In many aspects, anaphylaxis symptoms experienced by the affected vaccine recipients resemble those of infusion reactions to nanomedicines. Here we share lessons learned over a decade of nanomedicine research and discuss the current knowledge about several factors that individually or collectively contribute to infusion reactions to nanomedicines. We aim to use this knowledge to inform the SARS-CoV-2 lipid-nanoparticle-based mRNA vaccine field.

Posterior Scleritis Following COVID-19 Vaccination: A Case Report

PURPOSE

To report a case of posterior scleritis following COVID-19 vaccination.

STUDY DESIGN

Case report.

RESULTS

A 78-year-old female presented with headache and right-sided visual loss 10 days after the second dose of COVID-19 vaccine. 'Examination showed disc oedema and a serous retinal detachment. B-scan ultrasound showed thickening of the posterior sclera with retroscleral fluid. CT head with venogram excluded venous sinus thrombosis. The patient's condition improved rapidly with oral corticosteroids with restoration of vision and resolution of disc swelling and serous detachment by 4 weeks.

CONCLUSIONS

Posterior scleritis should be considered in patients presenting with headaches and blurred vision following vaccination. Timely diagnosis and treatment with corticosteroids can prevent permanent visual loss.

Can SARS-CoV-2 vaccine increase the risk of reactivation of Varicella zoster? A systematic review

INTRODUCTION

Although the COVID-19 vaccination is deemed safe, exact incidence and nature if adverse effects, particularly dermatological ones, are still unknown.

OBJECTIVE

To describe the demographic, clinical, morphological characteristics, outcomes, and timing of development of herpes zoster to the various COVID-19 vaccines. And to identify on whether COVID-19 vaccine has temporal relationship between development of herpes zoster (HZ).

METHODS

We have performed a systemic review of articles from PubMed and Embase using MeSH and keywords like "Shingles," "Herpes zoster," "Varicella zoster," "COVID-19," "Vaccine," "SARS-CoV-2." No filters including country of publication, language, type of articles were applied. Individual case report references were filtered for any pertinent cases.

RESULTS

A total of 54 cases consisting of 27 male and 27 female patients have been reported. There were cases with known risk factors for herpes zoster, which included age more than 50 years (n = 36), immunological disorders (n = 10), chronic disease (n = 25), metabolic disorder (n = 13), malignancy (n = 4), and psychiatric disorder (n = 2). The mean (SD) period between development of herpes zoster and COVID-19 vaccination was 7.64 (6.92) days. Majority of the cases were from the high-income and/or middle-income countries. 86.27% of the cases of HZ were reported due to mRNA vaccine. Thirty-six patients 36/45 (80%) developed herpes zoster following the priming dose of COVID-19 vaccine among those who received mRNA vaccine.

CONCLUSION

We could not establish definite link but there may be possible association between COVID-19 vaccine and shingles. Large-scale studies may help to understand the cause-effect relationship.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Reactivation of Varicella Zoster Virus after Vaccination for SARS-CoV-2

Seven immunocompetent patients aged > 50 years old presented with herpes zoster (HZ) infection in a median of 9 days (range 7-20) after vaccination against SARS-CoV-2. The occurrence of HZ within the time window 1-21 days after vaccination defined for increased risk and the reported T cell-mediated immunity involvement suggest that COVID-19 vaccination is a probable cause of HZ. These cases support the importance of continuing assessment of vaccine safety during the ongoing massive vaccination for the COVID-19 pandemic and encourage reporting and communication of any vaccination-associated adverse event.

Myopericarditis Associated With Smallpox Vaccination Among US Army Personnel - Fort Hood, Texas, 2018

OBJECTIVE

In March 2018, the US Department of Defense (DOD) added the smallpox vaccination, using ACAM2000, to its routine immunizations, increasing the number of persons receiving the vaccine. The following month, Fort Hood reported a cluster of 5 myopericarditis cases. The Centers for Disease Control and Prevention and the DOD launched an investigation.

METHODS

The investigation consisted of a review of medical records, establishment of case definitions, causality assessment, patient interviews, and active surveillance. A 2-sided exact rate ratio test was used to compare myopericarditis incidence rates.

RESULTS

This investigation identified 4 cases of probable myopericarditis and 1 case of suspected myopericarditis. No alternative etiology was identified as a cause. No additional cases were identified. There was no statistically significant difference in incidence rates between the observed cluster (5.23 per 1000 vaccinated individuals, 95% CI: 1.7-12.2) and the ACAM2000 clinical trial outcomes for symptomatic persons, which was 2.29 per 1000 vaccinated individuals (95% CI: 0.3-8.3).

CONCLUSIONS

Vaccination with ACAM2000 is the presumptive cause of this cluster. Caution should be exercised before considering vaccination campaigns for smallpox given the clinical morbidity and costs incurred by a case of myopericarditis. Risk of myopericarditis should be carefully weighed with risk of exposure to smallpox.

Safety Surveillance of Bivalent Meningococcal Group B Vaccine, Vaccine Adverse Event Reporting System, 2014-2018

BACKGROUND

In October 2014, MenB-FHbp (Trumenba, Pfizer) became the first meningococcal group B vaccine licensed in the United States. It is approved for use in individuals aged 10-25 years. Our objective was to evaluate the safety of MenB-FHbp postlicensure.

METHODS

The Vaccine Adverse Event Reporting System (VAERS) is a national passive vaccine safety surveillance system. We analyzed US VAERS reports for MenB-FHbp received from the date of licensure in October 2014 through December 2018. We described the characteristics of the persons and adverse events (AEs) reported and calculated reporting rates using the number of doses distributed. We used empirical Bayesian data mining to identify AEs reported at least twice as often as expected compared with all other vaccines.

RESULTS

VAERS received 2106 reports involving MenB-FHbp, representing 698 reports per million doses distributed. The median age of vaccinees was 17 years, and 55% were female. MenB-FHbp was given simultaneously with other vaccines in 37% of reports. Most reports (57%) described AEs that started on the day of or day after vaccination. The most common AEs reported were pyrexia (27%), headache (25%), and pain (16%). There were 44 serious reports (2% of all reports), among which 42 reported a hospitalization. Data mining identified disproportional reporting of headache, pyrexia, chills, and myalgia.

CONCLUSIONS

The AEs most commonly or disproportionately reported following MenB-FHbp were consistent with those identified in clinical trials as described in the US package insert. We did not identify any new safety issues.

Safety profile of rotavirus vaccines among individuals aged ≥8 months of age, United States, vaccine adverse event reporting system (VAERS), 2006-2019

INTRODUCTION

In 2006 and 2008, two live, oral rotavirus vaccines, RotaTeq (RV5) and Rotarix (RV1), were introduced into the routine immunization program in the United States. A previous rotavirus vaccine, RotaShield, was associated with an increased risk of intussusception, with data suggesting an age-dependent variation in risk. Advisory Committee on Immunization Practices (ACIP) currently recommends that RV5 or RV1 immunization be initiated by age 14 weeks and 6 days and completed by 8 months 0 days.

METHODS

We searched for U.S. VAERS reports of RV5, RV1, or unknown rotavirus vaccine brand among individuals aged ≥8 months. We analyzed reports by 2 age groups (individuals aged ≥8 months-≤5 years and ≥6 years), vaccine brand name, adverse event (AE) reported, classification of seriousness (death, non-death serious, and non-serious) and mode of exposure (direct vs. indirect exposure). For serious reports we reviewed available medical records and assigned a primary diagnosis.

RESULTS

VAERS received a total of 344 U.S. reports following rotavirus vaccination among individuals ≥8 months of age, 32 (9.3%) were serious. In the younger age-group, 307 (99%) of 309 reports followed direct vaccination of the child. In contrast, in individuals aged ≥6 years, 21 (60%) of 35 reports were via potential indirect exposure to a vaccinated child. The frequently reported AEs in the younger age-group were inappropriate schedule of drug administration 104 (34%) and drug administered to patient of inappropriate age 45 (15%); in the older group these were accidental exposure 9 (26%) and eye irritation 7 (20%). No difference in the safety profile was observed between RV1 and RV5.

CONCLUSIONS

We did not identify any unexpected AEs for RV vaccines among individuals aged ≥8 months. Health care providers should adhere to the ACIP recommended schedule and older individuals should apply necessary precautions to prevent potential secondary exposure from vaccinated children.

Prospects for a safe COVID-19 vaccine

Rapid development of an efficacious vaccine against the viral pathogen severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of the coronavirus disease 2019 (COVID-19) pandemic, is essential, but rigorous studies are required to determine the safety of candidate vaccines. Here, on behalf of the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) Working Group, we evaluate research on the potential risk of immune enhancement of disease by vaccines and viral infections, including coronavirus infections, together with emerging data about COVID-19 disease. Vaccine-associated enhanced disease has been rarely encountered with existing vaccines or viral infections. Although animal models of SARS-CoV-2 infection may elucidate mechanisms of immune protection, we need observations of enhanced disease in people receiving candidate COVID-19 vaccines to understand the risk of immune enhancement of disease. Neither principles of immunity nor preclinical studies provide a basis for prioritizing among the COVID-19 vaccine candidates with respect to safety at this time. Rigorous clinical trial design and postlicensure surveillance should provide a reliable strategy to identify adverse events, including the potential for enhanced severity of COVID-19 disease, after vaccination.

The state of vaccine safety science: systematic reviews of the evidence

This Review updates the scientific evidence assessing possible causal associations of adverse events following immunisation (AEFI) compiled in the 2012 report from the Institute of Medicine and the 2014 report from the Agency for Healthcare Research and Quality. For 12 of 46 AEFI examined, a causal relationship has been established with at least one vaccine currently routinely recommended to the general USA population: anaphylaxis, arthralgia or arthritis (mild, acute, and transient, not chronic), deltoid bursitis (when vaccine is administered improperly), disseminated varicella infection (in immune deficient individuals for whom the varicella vaccine is contraindicated), encephalitis, febrile seizures, Guillain-Barré syndrome, hepatitis (in immune deficient individuals for whom the varicella vaccine is contraindicated), herpes zoster, immune thrombocytopenic purpura, meningitis, and syncope. Other than mild acute and transient arthralgia or arthritis, which is very common in adult women after rubella vaccine, these adverse reactions are rare or very rare. Vaccines have an excellent safety profile overall and provide protection against infectious diseases to individuals and the general population.

Immune-mediated adverse reactions to vaccines

Vaccination continues to be the single most important and successful public health intervention, due to its prevention of morbidity and mortality from prevalent infectious diseases. Severe immunologically mediated reactions are rare and less common with the vaccine than the true infection. However, these events can cause public fearfulness and loss of confidence in the safety of vaccination. In this paper, we perform a systematic literature search and narrative review of immune-mediated vaccine adverse events and their known and proposed mechanisms, and outline directions for future research. Improving our knowledge base of severe immunologically mediated vaccine reactions and their management drives better vaccine safety and efficacy outcomes.

Challenges in evaluating post-licensure vaccine safety: observations from the Centers for Disease Control and Prevention

Introduction: Vaccination is one of the most successful and cost-effective public health interventions. Although vaccines undergo extensive safety and efficacy evaluations prior to licensure, vaccine safety assessment post-licensure is essential for detecting rare and longer-term adverse events (AEs) and maintaining public confidence in vaccines and recommended immunization programs. Despite the proven effect of vaccines to save lives and prevent disease and overwhelming evidence of vaccines' safety and societal benefit, like any drug, no vaccine can be considered as completely safe and completely effective. New vaccines continue to be introduced and require rapid safety assessment post-licensure through pharmacovigilance reports as well as epidemiologic studies to investigate any potential safety signals.Areas covered: We discuss selected challenges for conducting pharmacovigilance and epidemiologic studies of AEs after vaccination in the United States using the post-licensure safety surveillance infrastructure of the Centers for Disease Control and Prevention (CDC).Expert opinion: The availability of specific post-licensure surveillance systems to monitor and study AEs after vaccination, such as the Vaccine Adverse Event Reporting System, the Vaccine Safety Datalink, and the Clinical Immunization Safety Assessment Project, each with its unique set of strengths and limitations, provide a harmonized and supportive approach to meet several of these barriers.

Varicella Virus Vaccine Live: A 22-Year Review of Postmarketing Safety Data

Background

Varicella, a contagious infectious disease caused by varicella zoster virus (VZV), can result in hospitalization and, occasionally, death. Varicella virus vaccine live (VVVL [VARIVAX]) was introduced in the United States in 1995.

Methods

This comprehensive review of the VVVL safety profile is based on 22 years of postmarketing adverse event (AE) data received through spontaneous and noninterventional study reports submitted by health care providers and on a review of the published literature (cumulatively from March 17, 1995, through March 16, 2017, during which period >212 million doses were distributed globally).

Results

The VVVL safety profile was consistent with previous publications, with common AEs including varicella, rash, and pyrexia. AE reports have decreased over time, from ~500 per million doses in 1995 to ~40 per million doses in 2016; serious AEs comprise 0.8 reports per million doses. Secondary transmission was rare (8 confirmed cases); polymerase chain reaction analysis indicated that 38 of the 66 reported potential secondary transmission cases of varicella were attributable to wild-type VZV. The prevalence of major birth defects in the Pregnancy Registry was similar to that in the general US population. In total, 86 cases of death were reported after vaccination with VVVL; immunocompromised individuals appeared to be most at risk for a fatal varicella- or herpes zoster–related outcome.

Conclusions

This comprehensive 22-year review confirms the overall safety profile for VVVL, with no new safety concerns identified. Since VVVL’s introduction in 1995, notable declines in varicella cases and in varicella-related deaths have occurred compared with the prevaccination period.

Register-Based Ecologic Evaluation of Safety Signals Related to Pneumococcal Conjugate Vaccine in Children

Background:

In clinical trials of Pneumococcal Conjugate Vaccines (PCV), some adverse events have been reported more frequently in the PCV vaccinated. Ten-valent PCV (PCV10) was introduced into the Finnish National Vaccination Programme (NVP) in September 2010.

Objective:

We conducted an ecologic register-based study to investigate further the reported adverse events after PCV.

Methods:

This study included data obtained from the Finnish nationwide, population-based registers. First diagnoses of febrile seizures, breath-holding, urticarial rash, asthma and Kawasaki’s disease were included as outcomes obtained from the hospital discharge register. Data from Finnish Population Register during 2000-2014 for children age from 3 months to 10 years were used to estimate annual incidence rates. Incidence rate ratios of the outcomes were calculated between the target cohort of children eligible for PCV10 during 2010-2014 and a reference cohort before the NVP introduction (2004-2008).

Results:

No increases in the incidence of the adverse events after PCV10 introduction were found except for urticarial rash (incidence rate 2.48 vs. 1.60/1000 pyrs; incidence rate ratio, 1.54;95% CI 1.42-1.67). This increase was seen also in the unvaccinated older age groups in the post-vaccination era. The higher incidence of urticarial rash after the PCV10 introduction was due to the inclusion of diagnoses made in general medicine specialty in the discharge register because of a concomitant administrative change.

Conclusion:

The results do not support public health concerns related to the previously reported adverse events. Concomitant changes in health care administration and coding introduced bias, which was controlled after further evaluation of the data. We consider this register-based approach with real-world data feasible in the signal validation process after any signal detection.

Revisiting Influenza Vaccination Exemption

Serious adverse events after immunizations are rare. We review the case of a man who, 50 years earlier, experienced a serious adverse neurologic event 2 weeks after receiving influenza vaccine. He had received no subsequent seasonal influenza vaccinations, but after the risks and benefits were considered, he was vaccinated without adverse event that season.

Herpes zoster vaccine live: A 10 year review of post-marketing safety experience

BACKGROUND

Zoster vaccine is a single dose live, attenuated vaccine (ZVL) indicated for individuals ≥50 years-old for the prevention of herpes zoster (HZ). Safety data from clinical trials and post-licensure studies provided reassurance that ZVL is generally safe and well tolerated. The objective of this review was to provide worldwide post-marketing safety information following 10 years of use and >34 million doses distributed.

METHODS

All post-marketing adverse experience (AE) reports received worldwide between 02-May-2006 and 01-May-2016 from healthcare professionals following vaccination with ZVL and submitted to the MSD AE global safety database, were analyzed.

RESULTS

A total of 23,556 AE reports, 93% non-serious, were reported. Local injection site reactions (ISRs), with a median time-to-onset of 2 days, were the most frequently reported AEs followed by HZ. The majority of HZ reports were reported within 2 weeks of vaccination and considered, based on time-to-onset, pathogenesis of HZ, and data from clinical trials, to be caused by wild-type varicella-zoster virus (VZV). HZ confirmed by PCR analysis to be VZV Oka/Merck vaccine-strain was identified in an immunocompetent individual 8 months postvaccination and in 4 immunocompromised individuals. Disseminated HZ was reported very rarely (<1%) with 38% occurring in immunocompromised individuals. All reports of disseminated HZ confirmed by PCR as VZV Oka/Merck vaccine-strain were in individuals with immunosuppressive conditions and/or therapy at the time of vaccination.

CONCLUSIONS

The safety profile of ZVL, following 10 years of post-marketing use, was favorable and consistent with that observed in clinical trials and post-licensure studies.

The safety of live attenuated influenza vaccine in children and adolescents 2 through 17 years of age: A Vaccine Safety Datalink study

PURPOSE

To evaluate the safety of live attenuated influenza vaccine (LAIV) in children 2 through 17 years of age.

METHODS

The study was conducted in 6 large integrated health care organizations participating in the Vaccine Safety Datalink (VSD). Trivalent LAIV safety was assessed in children who received LAIV between September 1, 2003 and March 31, 2013. Eighteen pre-specified adverse event groups were studied, including allergic, autoimmune, neurologic, respiratory, and infectious conditions. Incident rate ratios (IRRs) were calculated for each adverse event, using self-controlled case series analyses. For adverse events with a statistically significant increase in risk, or an IRR > 2.0 regardless of statistical significance, manual medical record review was performed to confirm case status.

RESULTS

During the study period, 396 173 children received 590 018 doses of LAIV. For 13 adverse event groups, there was no significant increased risk of adverse events following LAIV. Five adverse event groups (anaphylaxis, syncope, Stevens-Johnson syndrome, adverse effect of drug, and respiratory failure) met criteria for manual medical record review. After review to confirm cases, 2 adverse event groups remained significantly associated with LAIV: anaphylaxis and syncope. One confirmed case of anaphylaxis was observed following LAIV, a rate of 1.7 per million LAIV doses. Five confirmed cases of syncope were observed, a rate of 8.5 per million doses.

CONCLUSIONS

In a study of trivalent LAIV safety in a large cohort of children, few serious adverse events were detected. Anaphylaxis and syncope occurred following LAIV, although rarely. These data provide reassurance regarding continued LAIV use.

Safety of a meningococcal group B vaccine used in response to two university outbreaks

OBJECTIVE

To assess the safety of meningococcal group B (MenB)-4C vaccine.

PARTICIPANTS

Undergraduates, dormitory residents, and persons with high-risk medical conditions received the MenB-4C vaccine two-dose series during mass vaccination clinics from 12/2013 through 11/2014.

METHODS

Adverse events (AEs) were identified by 15 minutes of observation postvaccination, spontaneous reports, surveys, and hospital surveillance. Causality was assessed for serious adverse events (SAEs).

RESULTS

16,974 persons received 31,313 MenB-4C doses. The incidence of syncope during the 15-minutes post-dose 1 was 0.88/1000 persons. 2% of participants spontaneously reported an AE (most common were arm pain and fever). 3 SAEs were suspected of being caused by the vaccine, including one case of anaphylaxis.

CONCLUSIONS

Most AEs reported were nonserious and consistent with previous clinical trial findings. Measures to prevent injury from syncope and to treat anaphylaxis should be available wherever vaccines are administered. Our safety evaluation supports the use of MenB-4C in response to outbreaks.

Reflections of a Vaccinologist: Lessons Learned About What We Can Do to Improve Trust in Vaccines and Vaccine Programsa

Public trust can be improved by learning from past mistakes, by establishing a standing forum for review of new concerns as they arise, and by maintaining a robust vaccine safety system. Developing standard guidelines for reporting causality assessment in case reports would help educate physicians and prevent future unnecessary concerns based on false assumptions of causal relationships.

Case Report of Subcutaneous Nodules and Sterile Abscesses Due to Delayed Type Hypersensitivity to Aluminum-Containing Vaccines

Routine childhood immunizations have resulted in great reductions in vaccine-preventable infectious diseases. Vaccine-related adverse events, albeit rare, can be of significant consequence. Although anaphylaxis, or type I hypersensitivity, is recognized as a potential reaction after vaccination, delayed type hypersensitivity or type IV reactions are less so. We present a case of persistent subcutaneous nodules and sterile abscesses in the setting of delayed type hypersensitivity to aluminum, confirmed by patch testing and recurrence on re-exposure. We review sources of aluminum in common immunizations, principles for treatment, and strategies for management of future vaccinations for this patient.

International Consensus (ICON): allergic reactions to vaccines

BACKGROUND

Routine immunization, one of the most effective public health interventions, has effectively reduced death and morbidity due to a variety of infectious diseases. However, allergic reactions to vaccines occur very rarely and can be life threatening. Given the large numbers of vaccines administered worldwide, there is a need for an international consensus regarding the evaluation and management of allergic reactions to vaccines.

METHODS

Following a review of the literature, and with the active participation of representatives from the World Allergy Organization (WAO), the European Academy of Allergy and Clinical Immunology (EAACI), the American Academy of Allergy, Asthma, and Immunology (AAAAI), and the American College of Allergy, Asthma, and Immunology (ACAAI), the final committee was formed with the purpose of having members who represented a wide-range of countries, had previously worked on vaccine safety, and included both allergist/immunologists as well as vaccinologists.

RESULTS

Consensus was reached on a variety of topics, including: definition of immediate allergic reactions, including anaphylaxis, approaches to distinguish association from causality, approaches to patients with a history of an allergic reaction to a previous vaccine, and approaches to patients with a history of an allergic reaction to components of vaccines.

CONCLUSIONS

This document provides comprehensive and internationally accepted guidelines and access to on-line documents to help practitioners around the world identify allergic reactions following immunization. It also provides a framework for the evaluation and further management of patients who present either following an allergic reaction to a vaccine or with a history of allergy to a component of vaccines.

Vaccination and 30-Day Mortality Risk in Children, Adolescents, and Young Adults

OBJECTIVE

This study evaluates the potential association of vaccination and death in the Vaccine Safety Datalink (VSD).

METHODS

The study cohort included individuals ages 9 to 26 years with deaths between January 1, 2005, and December 31, 2011. We implemented a case-centered method to estimate a relative risk (RR) for death in days 0 to 30 after vaccination.Deaths due to external causes (accidents, homicides, and suicides) were excluded from the primary analysis. In a secondary analysis, we included all deaths regardless of cause. A team of physicians reviewed available medical records and coroner's reports to confirm cause of death and assess the causal relationship between death and vaccination.

RESULTS

Of the 1100 deaths identified during the study period, 76 (7%) occurred 0 to 30 days after vaccination. The relative risks for deaths after any vaccination and influenza vaccination were significantly lower for deaths due to nonexternal causes (RR 0.57, 95% confidence interval [CI] 0.38-0.83, and RR 0.44, 95% CI 0.24-0.80, respectively) and deaths due to all causes (RR 0.72, 95% CI 0.56-0.91, and RR 0.44, 95% CI 0.28-0.65). No other individual vaccines were significantly associated with death. Among deaths reviewed, 1 cause of death was unknown, 25 deaths were due to nonexternal causes, and 34 deaths were due to external causes. The causality assessment found no evidence of a causal association between vaccination and death.

CONCLUSIONS

Risk of death was not increased during the 30 days after vaccination, and no deaths were found to be causally associated with vaccination.

Serum sickness-like reaction after influenza vaccination

Serum sickness (SS) and SS-like reaction (SSLR) are rare immune complex-mediated hypersensitivity illnesses characterised by key features of fever, rash, polyarthralgia or polyarthritis. They are self-limiting with an excellent prognosis, settling as the antigen is cleared. We describe a 30-year-old man who presented with fever, rash, polyarthralgia and subcutaneous soft tissue swelling in his hands and feet at day 5 after influenza vaccination. A thorough investigation for infective and autoimmune causes for the presenting symptoms was negative. Given the temporal relationship between the symptoms and influenza vaccination, clinical evidence and biological plausibility of influenza vaccination causing SSLR, a clinical diagnosis of SSLR was made. The patient was treated with anti-histamines, non-steroidal anti-inflammatories and glucocorticoids with gradual resolution of symptoms over 5 weeks.

Factors affecting the causality assessment of adverse events following immunisation in paediatric clinical trials: An online survey

BACKGROUND

Serious adverse events (SAEs) in clinical trials require reporting within 24h, including a judgment of whether the SAE was related to the investigational product(s). Such assessments are an important component of pharmacovigilance, however classification systems for assigning relatedness vary across study protocols. This on-line survey evaluated the consistency of SAE causality assessment among professionals with vaccine clinical trial experience.

METHODS

Members of the clinical advisory forum of experts (CAFÉ), a Brighton Collaboration online-forum, were emailed a survey containing SAEs from hypothetical vaccine trials which they were asked to classify. Participants were randomised to either two classification options (related/not related to study immunisation) or three options (possibly/probably/unrelated). The clinical scenarios, were (i) leukaemia diagnosed 5 months post-immunisation with a live RSV vaccine, (ii) juvenile idiopathic arthritis (JIA) 3 months post-immunisation with a group A streptococcal vaccine, (iii) developmental delay diagnosed at age 10 months after infant capsular group B meningococcal vaccine, (iv) developmental delay diagnosed at age 10 months after maternal immunisation with a group B streptococcal vaccine.

RESULTS

There were 140 respondents (72 two options, 68 three options). Across all respondents, SAEs were considered related to study immunisation by 28% (leukaemia), 74% (JIA), 29% (developmental delay after infant immunisation) and 42% (developmental delay after maternal immunisation). Having only two options made respondents significantly less likely to classify the SAE as immunisation-related for two scenarios (JIA p=0.0075; and maternal immunisation p=0.045). Amongst study investigators (n=43) this phenomenon was observed for three of the four scenarios: (JIA p=0.0236; developmental delay following infant immunisation p=0.0266; and developmental delay after maternal immunisation p=0.0495).

CONCLUSIONS

SAE causality assessment is inconsistent amongst study investigators and can be influenced by the classification systems available to them. There is a pressing need for SAE classification systems to be standardised across study protocols.

Pediatric anaphylactic adverse events following immunization in Victoria, Australia from 2007 to 2013

BACKGROUND

Anaphylaxis is a rare life-threatening adverse event following immunization (AEFI). Variability in presentation can make differentiation between anaphylaxis and other AEFI difficult. This study summarizes pediatric anaphylaxis AEFI reported to an Australian state-based passive surveillance system.

METHODS

All suspected and reported pediatric (<18 years) anaphylaxis AEFI notified to SAEFVIC (Surveillance of Adverse Events Following Vaccination In the Community) Melbourne, Australia, between May 2007 to May 2013 were analyzed. Clinical descriptions of the AEFI, using the internationally recognized Brighton Collaboration case definition (BCCD) and final outcome were documented.

RESULTS

93% (25/27) of AEFI classified as anaphylaxis met BCCD criteria, with 36% (9/25), assessed as the highest level of diagnostic certainty (Level 1). Median age was 4.7 years (range 0.3-16.2); 48% of cases were male. The vaccine antigens administered included: diphtheria, tetanus, acellular pertussis (DTaP) alone or in combination vaccines containing other antigens in 11 of 25 cases (44%); and live attenuated measles mumps rubella (MMR) vaccine for six (five also had other vaccines concomitantly administered). The estimated incidence rate of anaphylaxis for DTaP vaccines was 0.36 cases per 100,000 doses, and 1.25 per 100,000 doses for MMR vaccines. The majority of cases had rapid onset, but in 24% (6/25) of cases, first symptoms of anaphylaxis developed ≥30 min after immunization. In 60% (15/25) of cases, symptoms resolved ≤60 min of presentation. Intramuscular adrenaline was administered in 90% (18/25) of cases. All cases made a full recovery with no sequelae identified.

CONCLUSION

This comprehensive case series of pediatric anaphylaxis as an AEFI identified that diagnostic criteria are useful when applied to a passive vaccine surveillance system when adequate clinical information is available. Anaphylaxis as an AEFI is rare and usually begins within 30 min of vaccination. However, healthcare professionals and vaccinees/parents should be aware that onset of anaphylaxis can be delayed beyond 30 min following immunization and that medical attention should be sought promptly if anaphylaxis is suspected.

Analyzing and strengthening the vaccine safety program in Manitoba

BACKGROUND

The emergence of a novel influenza A virus in 2009 and the rapid introduction of new pandemic vaccines prompted an analysis of the current state of the adverse events following immunization (AEFI) surveillance response in several provinces.

OBJECTIVES

To highlight aspects of the situational analysis of the Manitoba Health, Healthy Living and Seniors (MHHLS's) AEFI surveillance system and to demonstrate how common business techniques could be usefully applied to a provincial vaccine safety monitoring program.

METHOD

Situational analysis of the AEFI surveillance system in Manitoba was developed through a strengths-weaknesses-opportunities-threats (SWOT) analysis and informed by the National Immunization Strategy vaccine safety priorities. Strategy formulation was developed by applying the threats-opportunities-weaknesses-strengths (TOWS) matrix.

RESULTS

Thirteen strategies were formulated that use strengths to either take advantage of opportunities or avoid threats, that exploit opportunities to overcome weaknesses, or that rectify weaknesses to circumvent threats. These strategies entailed the development of various tools and resources, most of which are either actively underway or completed.

CONCLUSION

The SWOT analysis and the TOWS matrix enabled MHHLS to enhance the capacity of its vaccine safety program.

Live vaccine use and safety in DiGeorge syndrome

OBJECTIVE

Live vaccines are generally contraindicated in patients with DiGeorge syndrome (DGS), a congenital disorder characterized by cellular immune deficiency. Vaccine utilization and safety in this population are not well described. This study examined vaccination patterns and adverse events following live immunization (AEFLI) in these individuals.

METHODS

A multicenter retrospective cohort study was conducted in subjects with DGS confirmed by fluorescence in situ hybridization assay (chromosome 22q11.2 microdeletion). Live vaccine-preventable illnesses, vaccination coverage and timeliness, and AEFLIs in the 56-day window after live vaccination were examined. Bivariate and multivariable analyses assessed the impact of demographics medical history, timing of diagnostic confirmation, and preceding immune function on vaccination patterns and AEFLIs.

RESULTS

Of 194 subjects, 77% and 75% received measles-mumps-rubella (MMR) and varicella vaccines, respectively; 58% completed recommended vaccinations by age 19 to 35 months. Adverse events occurred after 14% and 20% of MMR and varicella vaccine doses, respectively. Most events were minor, few were serious, and no deaths were reported in post-live vaccination windows. Although early diagnostic confirmation negatively affected live vaccination coverage and timeliness (P < .001), baseline CD4% did not differ between subjects who did or did not receive live vaccines by 12 to 18 months. Among varicella vaccine recipients, those with a subsequent adverse event had a lower preceding CD4% (24.8% ± 7.3%) than those without (35.5% ± 11.7%) (P < .05); no CD4% differences were observed with MMR vaccination. Fourteen unvaccinated subjects experienced live vaccine-preventable illnesses.

CONCLUSIONS

Live vaccines were frequently given and generally well-tolerated among patients with DGS with mild-to-moderate immunosuppression.

Assessment of causality of individual adverse events following immunization (AEFI): a WHO tool for global use

Serious illnesses or even deaths may rarely occur after childhood vaccinations. Public health programs are faced with great challenges to establish if the events presenting after the administration of a vaccine are due to other conditions, and hence a coincidental presentation, rather than caused by the administered vaccines. Given its priority, the Global Advisory Committee for Vaccine Safety (GACVS) commissioned a group of experts to review the previously published World Health Organization (WHO) Adverse Event Following Immunization (AEFI) causality assessment methodology and aide-memoire, and to develop a standardized and user friendly tool to assist health care personnel in the processing and interpretation of data on individual events, and to assess the causality after AEFIs. We describe a tool developed for causality assessment of individual AEFIs that includes: (a) an eligibility component for the assessment that reviews the diagnosis associated with the event and identifies the administered vaccines; (b) a checklist that systematically guides users to gather available information to feed a decision algorithm; and (c) a decision support algorithm that assists the assessors to come to a classification of the individual AEFI. Final classification generated by the process includes four categories in which the event is either: (1) consistent; (2) inconsistent; or (3) indeterminate with respect of causal association; or (4) unclassifiable. Subcategories are identified to assist assessors in resulting public health decisions that can be used for action. This proposed tool should support the classification of AEFI cases in a standardized, transparent manner and to collect essential information during AEFI investigation. The algorithm should provide countries and health officials at the global level with an instrument to respond to vaccine safety alerts, and support the education, research and policy decisions on immunization safety.

Severe serum sickness after H1N1 influenza vaccination

In this study, the case of a 48-year-old man with severe serum sickness reaction in response to H1N1 influenza immunization is reported. He presented with renal failure and several of the classic signs reported in early descriptions of serum sickness by Clemens von Pirquet and Bela Schick including lymphadenopathy, urticarial skin eruption and facial edema. Serum immunologic studies and tissue histology/immunohistochemistry assisted in firmly establishing the diagnosis in this case. With appropriate therapy, the patient's rash, edema and lymphadenopathy resolved and normal renal function returned. This first reported case of severe serum sickness to H1N1 vaccine is particularly important in light of the Centers for Disease Control and Prevention's recommendation for universal vaccination against influenza, including H1N1, in patients 6 months and older. With increasing numbers of patients receiving this vaccine, even rare adverse reactions may be experienced by numerous individuals. It is imperative that clinicians remain vigilant about possible reactions and quickly institute appropriate therapy.