Karina Top

University of Alberta | UAlberta

Background Live attenuated varicella vaccine (LAVV) has historically been contraindicated in children who are immunocompromised due to solid organ transplant (SOT) because of safety concerns. Recently, clinical guidelines were developed that support post‐transplant varicella vaccination in selected SOT recipients based on emerging evidence of LAVV...

Introduction/Background Changes in relative virulence of SARS-CoV-2 lineages among children remain poorly understood, yet are important considerations for vaccination and health resource management. Further evidence is needed to assess the burden of severe paediatric COVID-19 due to the Omicron variant. Objectives In this study, we aimed to compar...

Objectives: Individuals and healthcare providers may be uncertain about the safety of revaccination after an adverse event following immunization (AEFI). We identified factors associated with physician recommendation for revaccination and participant intention to be revaccinated among patients with adverse events following immunization (AEFIs) ass...

Background: Paediatric inflammatory multisystem syndrome (PIMS) is a rare condition temporally associated with SARS-CoV-2 infection. Using national surveillance data, we compare presenting features and outcomes among children hospitalized with PIMS by SARS-CoV-2 linkage, and identify risk factors for intensive care (ICU). Methods: Cases were rep...

Purpose: Synthesize the available evidence on the immunogenicity, safety, and effectiveness of live-attenuated varicella vaccine in solid organ transplant (SOT) recipients. Methods: Medline and EMBASE were searched using predefined search terms to identify relevant studies. Included articles reported varicella vaccine administration in the post-...

Background: People with inflammatory or autoimmune diseases are recommended to continue immunomodulatory biologic agents throughout pregnancy. However, concerns regarding potential immunosuppression in infants exposed to biologic agents have led to recommendations to avoid live vaccines in the first 6-12 months of life. We aimed to examine whether...

Early in COVID-19 vaccine rollout, expert recommendations about vaccination while pregnant and breastfeeding changed rapidly. This paper addresses the (re)production of gendered power relations in these expert discourses and recommendations in Canada. We collected texts about COVID-19 vaccine use in pregnancy (N = 52) that Canadian health organizat...

Objectives: To evaluate immunocompromising conditions and subgroups of immunocompromise as risk factors for severe outcomes among children admitted for influenza. Methods: We performed active surveillance for laboratory-confirmed influenza hospitalizations among children ≤16 years old at the 12 Canadian Immunization Monitoring Program Active hos...

Vaccines have had a tremendous impact on reducing the burden of infectious diseases, however, they have the potential to cause adverse events following immunisation (AEFIs). Prelicensure clinical trials are limited in their ability to detect rare AEFI that may occur in less than one per thousand individuals. While post‐marketing surveillance system...

Background and objectives Safety and effectiveness concerns may preclude physicians from recommending vaccination in mild/moderate inborn errors of immunity (IEI). This study describes attitudes and practices regarding vaccination among physicians who care for patients with mild/moderate B cell or mild/moderate combined immunodeficiencies (CID) and...

Background Children living with chronic comorbid conditions are at increased risk for severe COVID-19, though there is limited evidence regarding the risks associated with specific conditions and which children may benefit from targeted COVID-19 therapies. The objective of this study was to identify factors associated with severe disease among hosp...

The Brighton Collaboration (BC) has formulated a number of case definitions which have primarily been applied to adverse events of special interest in the context of vaccine safety surveillance. This is a revision of the 2007 BC case definition for anaphylaxis. Recently, the BC definition has been widely used for evaluating reports of suspected ana...

Background: Adults previously infected with SARS-CoV-2 develop short-term immunity and may have increased reactogenicity to COVID-19 vaccines. This prospective, multi-center active surveillance cohort study examined the short-term safety of COVID-19 vaccines in adults with a prior history of SARS-CoV-2. Methods: Canadian adults vaccinated betwee...

Background Meningococcal conjugate vaccine (MCV) programs in Canada began in 2002. Objectives This study examines the most recent surveillance data to describe the current Canadian epidemiology of invasive meningococcal disease (IMD) and the effect of MCV programs, especially on age and serogroup distribution. Design/Methods Active metropolitan a...

Background Children living with chronic comorbid conditions are at increased risk for severe COVID-19 disease, though there is limited evidence regarding the risks associated with specific conditions and which children may benefit from targeted COVID-19 therapies. Age-specific baseline indicators of COVID-19 severity are also needed to evaluate the...

PurposeThe objective of this study was to describe the clinical course and outcomes in children with technology dependence (TD) hospitalized with SARS-CoV-2 infection.Methods Seventeen pediatric hospitals (15 Canadian and one each in Iran and Costa Rica) included children up to 17 years of age admitted February 1, 2020, through May 31, 2021, with d...

Objective To identify risk factors for severe disease in children hospitalised for SARS-CoV-2 infection. Design Multicentre retrospective cohort study. Setting 18 hospitals in Canada, Iran and Costa Rica from 1 February 2020 to 31 May 2021. Patients Children<18 years of age hospitalised for symptomatic PCR-positive SARS-CoV-2 infection, includin...

Objectives To estimate the risk of recurrence of adverse events following immunization (AEFIs) upon re-vaccination and to determine among patients with suspected vaccine allergy whether allergy skin test positivity was associated with AEFI recurrence. Study Design This prospective observational study included patients assessed in the Canadian Spec...

Background Pregnant individuals have been receiving COVID-19 vaccines following pre-authorisation clinical trials in non-pregnant people. This study aimed to determine the frequency and nature of significant health events among pregnant females after COVID-19 vaccination, compared with unvaccinated pregnant controls and vaccinated non-pregnant indi...

Exclusion of pregnant and breastfeeding women from the pivotal randomized controlled trials for COVID-19 vaccines that led to emergency regulatory approval created gaps in data needed for vaccine policy, healthcare provider recommendations, and women's decisions about vaccination. We argue that such knowledge gaps increase potential for vaccine hes...

Kawasaki disease (KD) is an acute systemic vasculitis primarily affecting children younger than 5 y of age that has been reported as an adverse event following immunization (AEFI). The Canadian Immunization Monitoring Program ACTive (IMPACT) conducts active surveillance for KD following immunization across Canada. We characterized KD cases reported...

Background: The gaps in clinical trial evidence about vaccination in pregnancy have serious implications for health care worker and public misunderstandings. Contradictions between National Immunization Technical Advisory Group (NITAG) recommendations and regulatory product labeling information contribute to misinformation about vaccine safety and...

Within two years, novel SARS-CoV-2 vaccines have been developed, rigorously evaluated in large phase 3 trials, and administered to over 5 billion individuals globally. However, adverse events of special interest (AESIs) have been described post-implementation, including myocarditis after mRNA vaccines and thrombosis with thrombocytopenia syndrome (...

Background: Post-licensure adverse events following immunization (AEFI) surveillance is conducted to monitor vaccine safety, such as identifying batch/brand issues and rare reactions, which consequently improves community confidence. The integration of technology has been proposed to improve AEFI surveillance, however, there is an absence of descr...

Background Paediatric inflammatory multisystem syndrome (PIMS) is a rare but serious condition temporally associated with SARS-CoV-2 infection. Using the Canadian Paediatric Surveillance Program (CPSP), a national surveillance system, we aimed to 1) study the impact of SARS-CoV-2 linkage on clinical and laboratory characteristics, and outcomes in h...

Purpose: The objective of this study was to describe the clinical course and outcomes in children with technology-dependence (TD) hospitalized with SARS-CoV-2 infection. Methods: Seventeen pediatric hospitals (15 Canadian and one each in Iran and Costa Rica) included children up to 17 years of age admitted February 1, 2020, through May 31, 2021, wi...

Background Children living with chronic comorbid conditions are at increased risk for severe COVID-19, though there is limited evidence regarding the risks associated with specific conditions and which children may benefit from targeted COVID-19 therapies. The objective of this study was to identify factors associated with severe disease among hosp...

Background: The COVID-19 pandemic resulted in unprecedented implementation of wide-ranging public health measures globally. During the pandemic, dramatic decreases in seasonal influenza virus detection have been reported worldwide. Information on the impact on paediatric influenza-related hospitalisations is limited. We describe influenza-related h...

https://doi.org/10.1016/S0140-6736(22)00379-8

Age is the most important determinant of COVID-19 severity. Infectious disease severity by age is typically J-shaped, with infants and the elderly carrying a high burden of disease. We report on the comparative disease severity between infants and older children in a multicenter retrospective cohort study of children 0 to 17 years old admitted for...

Background Pregnant individuals have been receiving COVID-19 vaccines following pre-authorization clinical trials in non-pregnant people. This study aimed to determine significant health events amongst pregnant females after COVID-19 vaccination, compared with unvaccinated pregnant controls and vaccinated non-pregnant individuals. Methods Study pa...

Introduction COVID-19 vaccines require enhanced safety monitoring after emergency approval. The Canadian National Vaccine Safety Network monitors the safety of COVID-19 vaccines and provides enhanced monitoring for healthy, auto-immune, immunocompromised, pregnant and breastfeeding populations and allows for the detection of safety signals. Method...

(Abstracted from JAMA 2021;325:2285–2293) Vaccination for seasonal influenza is an important health intervention, even for pregnant women. Influenza vaccination helps to reduce the risk of severe influenza illness for the mother and child.

Age is the most important determinant of COVID-19 severity. Infectious disease severity by age is typically J-shaped, with infants and the elderly carrying a high burden of disease. We report on the comparative disease severity between infants and older children in a multicenter retrospective cohort study of children 0 to 17 year old admitted for a...

Importance: Children are less likely than adults to have severe outcomes from SARS-CoV-2 infection and the corresponding risk factors are not well established. Objective: To identify risk factors for severe disease in symptomatic children hospitalized for PCR-positive SARS-CoV-2 infection. Design: Cohort study, enrollment from February 1, 2020 unti...

Background: Risk factors for severe outcomes of SARS-CoV-2 infection are not well established in children. We sought to describe pediatric hospital admissions associated with SARS-CoV-2 infection in Canada and identify risk factors for more severe disease. Methods: We conducted a national prospective study using the infrastructure of the Canadia...

Group A Streptococcus (GAS) pharyngitis is a common clinical syndrome in primary care, yet controversy remains regarding the best approach to diagnosis and treatment, including the benefits of antibiotics. Children who are likely to have GAS pharyngitis based on history or physical examination should have a throat swab and, when positive, be treate...

La pharyngite à streptocoque du groupe A est un syndrome clinique courant en première ligne, mais une controverse subsiste quant à la meilleure démarche diagnostique et thérapeutique, y compris les bienfaits des antibiotiques. Les enfants qui, d’après l’anamnèse ou l’examen physique, risquent de souffrir de ce type de pharyngite, doivent se soumett...

Despite ample evidence of the safety and efficacy of the influenza vaccine and the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine during pregnancy, two-thirds of pregnant women do not receive these vaccines. Providers have a significant role in increasing prenatal vaccine uptake. It is important to understand how different sources of v...

Importance Seasonal influenza vaccination in pregnancy can reduce influenza illness among pregnant women and newborns. Evidence is limited on whether seasonal influenza vaccination in pregnancy is associated with adverse childhood health outcomes. Objective To assess the association between maternal influenza vaccination during pregnancy and early...

Background: The World Health Organization recommends immunization with inactivated influenza vac-cine (IIV) and tetanus-diphtheria-acellular pertussis (Tdap) vaccine during pregnancy. Yet, product label-ling information for IIV and Tdap sends a different message. In a previous study, we developed evidence-based statements about vaccination in pregn...

Potential conflicts of interest in vaccine research can lead to negative consequences that undermine public trust and thereby put communities at risk. However, collaborations that may give rise to potential conflicts between interests can also greatly facilitate appropriate, scientifically robust, and timely vaccine development, implementation, and...

Objectives Children with epilepsy are at increased risk of complications from vaccine-preventable infections, yet information on vaccine coverage in these children is scarce. We aimed to compare vaccine coverage among children with epilepsy to children without epilepsy. Study design We conducted a retrospective cohort study including all 2005–2013...

This is a Brighton Collaboration Case Definition of the term “Multisystem Inflammatory Syndrome in Children and Adults (MIS-C/A)” to be utilized in the evaluation of adverse events following immunization. The case definition was developed by topic experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of activ...

Objectives: Our objective was to develop and validate a virtual patient (VP) learning module to educate pediatric residents about antimicrobial stewardship (AMS) principles. A VP module on complicated pneumonia was developed by experts in AMS and pediatric infectious diseases using the online platform DecisionSim™. Decision points were based on AM...

Sentinel surveillance of acute hospitalisations in response to infectious disease emergencies such as the 2009 influenza A(H1N1)pdm09 pandemic is well described, but recognition of its potential to supplement routine public health surveillance and provide scalability for emergency responses has been limited. We summarise the achievements of two nat...

Background The Canadian National Vaccine Safety (CANVAS) network monitors the safety of seasonal influenza vaccines in Canada.AimTo provide enhanced surveillance for seasonal influenza and pandemic influenza vaccines.Methods In 2017/18 and 2018/19 influenza seasons, adults (≥ 15 years of age) and parents of children vaccinated with the seasonal inf...

Background: In children with epilepsy, fever and illness are known triggers for seizure; therefore, clinicians and parents could be concerned that immunization-induced inflammation and fever could also trigger seizures. We sought to estimate the risk of emergency department (ED) visit or hospitalization for epilepsy/seizure and all causes after im...

Background Neurological adverse events following immunization (AEFI) remain poorly characterized. Our objective was to describe pediatric acute and chronic encephalopathy and encephalitis cases following immunization reported via active sentinel surveillance from 1992 to 2012. Methods This case series provides a descriptive analysis of encephalopa...

Background Concern about adverse events following immunization is frequently cited by both those who receive or decline vaccines. Neurological adverse events are especially concerning. Objectives Our aim was to detect associations between seasonal influenza vaccination and the occurrence of severe anesthesia/paresthesia or severe headaches. Metho...

Background: There is no uniform guideline for post-chemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of post-chemotherapy DTaP-IPV-Hib and pneumococcal vaccination among previously vacci...

The article provides the definition for Neonatal Seizures for collection of of neonatal and vaccine safety research.

Background: National Regulatory Authorities approve the indications for vaccine use in the product information. Occasionally, National Immunization Technical Advisory Groups (NITAGs) make off-label recommendations for use in different age groups, populations, and dosing schedules from the product information. We sought to determine the rationale,...

Background: Product labelling information describing the use of vaccines in pregnancy continues to contain cautionary language even after clinical and epidemiological evidence of safety becomes available. This language raises safety concerns among healthcare providers who may hesitate to recommend vaccines during pregnancy. Purpose: To develop c...

Chest wall masses in the pediatric population are relatively rare, and the differential diagnosis predominantly includes neoplastic soft tissue or osseous tumours, either benign or malignant in etiology, although local infectious processes represent additional diagnostic possibilities. Among recent immigrants, a more diverse array of less commonly...

Growing evidence suggests receipt of live‐attenuated viral vaccines after solid organ transplant (SOT) has occurred and is safe and needed due to lapses in herd immunity. A 2‐day consortium of experts in infectious diseases, transplantation, vaccinology, and immunology was held with the objective to review evidence and create expert recommendations...

Objective To determine whether any association exists between exposure to 2009 pandemic H1N1 (pH1N1) influenza vaccination during pregnancy and negative health outcomes in early childhood. Design Retrospective cohort study. Setting Population based birth registry linked with health administrative databases in the province of Ontario, Canada. Par...

Objective: To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines ininfants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6 months of life. Methods: Using a standardized searc...

Introduction: More women with autoimmune and inflammatory conditions are being treated with monoclonal antibody biologics (mAbs) during their pregnancy, to maintain clinical remission. The use of anti-tumor necrosis factor alpha agents in pregnancy appear to be safe but less is known regarding other mAbs, such as anti-integrins and anti-cytokine ag...

Background: While adverse events following immunization (AEFI) are frequent, there are limited data on the safety of reimmunizing patients who had a prior AEFI. Our objective was to estimate the rate and severity of AEFI recurrences. Methods: We analyzed data from the AEFI passive surveillance system in Quebec, Canada that collects information o...

Influenza has been associated with neurological complications. We describe the case of a toddler who presented with symptoms and signs of acute encephalopathy and hydrocephalus. Neuroimaging demonstrated cerebral edema and multifocal diffusion restriction in the thalamus and splenium of the corpus callosum. Influenza A was detected from the nasopha...

Background: Influenza immunization is recommended in pregnancy to prevent severe infections in pregnant women and newborns, yet vaccine uptake remains low. Studies suggest that cautionary language in vaccine product monographs regarding safety and use in pregnancy affects health care providers' perceptions of vaccine safety and how they counsel pre...

Background: In children with epilepsy, fever and infection can trigger seizures. Immunization can also induce inflammation and fever, which could theoretically trigger a seizure. The risk of seizure after immunization in children with pre-existing epilepsy is not known. The study objective was to determine the risk of medically attended seizure af...

We studied the epidemiology of Haemophilus influenzae type b (Hib) infections among children with cancer admitted to Canadian pediatric hospitals. From 1991-2014, 13 cases among children with cancer were identified through active surveillance. Average age was 6.7 years. Six of 7 cases eligible for infant immunization were age-appropriately immunize...

Background Smart phone use by medical professionals is ubiquitous. In a recent survey, > 90% of health care providers were interested in locally developed antimicrobial stewardship (AMS) and infectious diseases applications (“apps”). We describe the process by which our antimicrobial stewardship program (ASP) developed an app to provide guidance re...