Maternal varicella antibodies in children aged less than one year: Assessment of antibody decay.

Objectives: To investigate maternal antibody levels to varicella in infants <12 months of age in Ontario, Canada.

Study Design: In this study, we included specimens from infants <12 months of age, born at ≥37 weeks gestational age, who had sera collected at The Hospital for Sick Children (Toronto, Canada) between 2014-2016. We tested sera using a glycoprotein-based enzyme-linked immunosorbent assay (gpELISA).

Antibiotic use in children hospitalised for influenza, 2010-2021: the Canadian Immunization Monitoring Program Active (IMPACT).

Purpose: To determine characteristics associated with inappropriate antibiotic use amongst children hospitalised for influenza.

Methods: We performed active surveillance for laboratory-confirmed influenza hospitalizations amongst children ≤ 16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from September 2010 to August 2021. Antibiotic use was presumed appropriate if any of the following indications were met: age < 1 month, immunocompromised, hemoglobinopathy, laboratory-confirmed bacterial infection, radiographically confirmed pneumonia, admission to an intensive care unit and mechanical ventilation.

Antibody and B-cell Immune Responses Against Bordetella Pertussis Following Infection and Immunization.

Neither immunization nor recovery from natural infection provides life-long protection against Bordetella pertussis. Replacement of a whole-cell pertussis (wP) vaccine with an acellular pertussis (aP) vaccine, mutations in B. pertussis strains, and better diagnostic techniques, contribute to resurgence of number of cases especially in young infants.

PreHevbrio: the first approved 3-antigen hepatitis B vaccine.

Introduction: Hepatitis B remains a major cause of death and morbidity worldwide. Universal childhood immunization programs have been very successful, but many adults remain unprotected or are not optimally protected. PreHevbrio [Hepatitis B Vaccine (recombinant)] is a highly immunogenic 3-antigen (S/pre-S1/pre-S2) hepatitis B vaccine (3A-HBV) that recently received marketing authorization in the United States (2021), the European Union, United Kingdom (2022 - brand name PreHevbri), and Canada (2022- brand name PreHevbrio) for the prevention of infection caused by all known subtypes of the hepatitis B virus and the delta virus in adults 18 years and older.

Benefits of Combining Molecular Biology and Controlled Human Infection Model Methodologies in Advancing Vaccine Development.

Infectious diseases continue to account for a significant portion of global deaths despite the use of vaccines for several centuries. Immunization programs around the world are a testament to the great success of multiple vaccines, yet there are still diseases without vaccines and others that require safer more effective ones. Addressing uncontrolled and emerging disease threats is restrained by the limitations and bottlenecks encountered with traditional vaccine development paradigms.

Uptake of pertussis immunization in pregnancy and determinants of vaccination in Toronto, Canada.

Introduction: Pertussis causes significant morbidity and mortality in infants aged <6 months. Maternal pertussis vaccination during pregnancy has been recommended in Canada since 2018 to reduce these negative outcomes. In the absence of routine immunization coverage data, our objective was to evaluate uptake in Toronto, Canada.

Immunity of Canadians and risk of epidemics workshop - Conference report.

On November 18-19, 2019, the Immunity of Canadians and Risk of Epidemics (iCARE) Network convened a workshop in Toronto, Ontario, Canada. The objectives of the workshop were to raise the profile of sero-epidemiology in Canada, discuss best practice and methodological innovations, and strategize on the future direction of sero-epidemiology work in Canada. In this conference report, we describe the presentations and discussions from the workshop, and comment on the impact of the COVID-19 pandemic on serosurveillance initiatives, both in Canada and abroad.

Tdap vaccine in pregnancy and immunogenicity of pertussis and pneumococcal vaccines in children: What is the impact of different immunization schedules?

Background: In 2019, the 3 + 1 schedule for children's vaccination (2-4-6-18 months old) was changed for a reduced 2 + 1 schedule (2-4-12 months old) in Quebec, Canada. We compared the post-booster anti-pertussis and anti-pneumococcus IgG antibody concentrations among children of Tdap-vaccinated and unvaccinated mothers for different vaccine schedules and vaccine formulations.

Methods: We conducted an observational cohort study.

Lessons learned from the experiences and perspectives of frontline healthcare workers on the COVID-19 response: a qualitative descriptive study.

Background: During the COVID-19 pandemic, healthcare systems and healthcare workers (HCWs) faced significant demands and unique challenges. In this qualitative study, we explore the effects of the COVID-19 public health policies on British Columbia's frontline HCWs, describe what worked in the management of the pandemic, and elucidate the lessons learned that could be applied to future pandemic preparedness, recovery and response.

Methods: This qualitative descriptive study is part of a larger, national multi-case study on pandemic policy communication and uptake.

Pediatric RSV-Associated Hospitalizations Before and During the COVID-19 Pandemic.

Importance: Respiratory syncytial virus (RSV) is a leading cause of pediatric hospitalizations.

Objective: To describe the epidemiology and burden of RSV-associated hospitalizations among children and adolescents in Canadian tertiary pediatric hospitals from 2017 to 2022, including changes during the COVID-19 pandemic.

Design, Setting, And Participants: This cross-sectional study was conducted during 5 RSV seasons (2017-2018 to 2021-2022) at 13 pediatric tertiary care centers from the Canadian Immunization Monitoring Program Active (IMPACT) program.

Parent and healthcare provider views of live varicella vaccination of pediatric solid organ transplant recipients.

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 safety. This qualitative study sought to explore barriers and facilitators to implementing the new guidelines, as well as acceptability of LAVV among healthcare providers (HCPs) and parents.

Factors associated with intention for revaccination among patients with adverse events following immunization.

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) assessed in the Canadian Special Immunization Clinic (SIC) Network from 2013 to 2019.

Methods: This prospective observational study included patients assessed in the Canadian Special Immunization Clinic Network from 2013 to 2019 for an AEFI who required additional doses of the vaccine temporally associated with their AEFI.

Predictors of Severity of Influenza-Related Hospitalizations: Results From the Global Influenza Hospital Surveillance Network (GIHSN).

Background: The Global Influenza Hospital Surveillance Network (GIHSN) has since 2012 provided patient-level data on severe influenza-like-illnesses from >100 participating clinical sites worldwide based on a core protocol and consistent case definitions.

Methods: We used multivariable logistic regression to assess the risk of intensive care unit admission, mechanical ventilation, and in-hospital death among hospitalized patients with influenza and explored the role of patient-level covariates and country income level.

Results: The data set included 73 121 patients hospitalized with respiratory illness in 22 countries, including 15 660 with laboratory-confirmed influenza.

Leveraging Influenza Virus Surveillance From 2012 to 2015 to Characterize the Burden of Respiratory Syncytial Virus Disease in Canadian Adults ≥50 Years of Age Hospitalized With Acute Respiratory Illness.

Background: Respiratory syncytial virus (RSV) disease in older adults is undercharacterized. To help inform future immunization policies, this study aimed to describe the disease burden in Canadian adults aged ≥50 years hospitalized with RSV.

Methods: Using administrative data and nasopharyngeal swabs collected from active surveillance among adults aged ≥50 years hospitalized with an acute respiratory illness (ARI) during the 2012-2013, 2013-2014, and 2014-2015 influenza seasons, RSV was identified using a respiratory virus multiplex polymerase chain reaction test to describe the associated disease burden, incidence, and healthcare costs.

Burden of illness associated with Respiratory Syncytial Virus (RSV)-related hospitalizations among adults in Ontario, Canada: A retrospective population-based study.

Background: Globally, RSV is a common viral pathogen that causes 64 million acute respiratory infections annually. Our objective was to determine the incidence of hospitalization, healthcare resource use and associated costs of adults hospitalized with RSV in Ontario, Canada.

Methods: To describe the epidemiology of adults hospitalized with RSV, we used a validated algorithm applied to a population-based healthcare utilization administrative dataset in Ontario, Canada.

Age Differences in Comorbidities, Presenting Symptoms, and Outcomes of Influenza Illness Requiring Hospitalization: A Worldwide Perspective From the Global Influenza Hospital Surveillance Network.

Background: The Global Influenza Hospital Surveillance Network (GIHSN) was established in 2012 to conduct coordinated worldwide influenza surveillance. In this study, we describe underlying comorbidities, symptoms, and outcomes in patients hospitalized with influenza.

Methods: Between November 2018 and October 2019, GIHSN included 19 sites in 18 countries using a standardized surveillance protocol.

Identifying and addressing the impacts of the COVID-19 pandemic on school-based immunisation programmes in the Canadian Maritimes: a mixed methods study protocol.

Introduction: The COVID-19 pandemic highlighted the importance of keeping up to date on routine vaccinations. Throughout the pandemic, many routine vaccine programmes in Canada were paused or cancelled, including school-based immunisation programmes (SBIP). This resulted in decreased coverage for many vaccine-preventable diseases.

Convergence in Mobility Data Sets From Apple, Google, and Meta.

Background: The higher movement of people was one of the variables that contributed to the spread of the infectious agent SARS-CoV-2 during the COVID-19 pandemic. Governments worldwide responded to the virus by implementing measures that would restrict people's movements, and consequently, the spread of the disease. During the onset of the pandemic, the technology companies Apple, Google, and Meta used their infrastructure to anonymously gather mobility reports from their users.

Evaluating the effectiveness of lockdowns and restrictions during SARS-CoV-2 variant waves in the Canadian province of Nova Scotia.

Introduction: After the initial onset of the SARS-CoV-2 pandemic, the government of Canada and provincial health authorities imposed restrictive policies to limit virus transmission and mitigate disease burden. In this study, the pandemic implications in the Canadian province of Nova Scotia (NS) were evaluated as a function of the movement of people and governmental restrictions during successive SARS-CoV-2 variant waves (i.e.

The persistence of seroprotective levels of antibodies after vaccination with PreHevbrio, a 3-antigen hepatitis B vaccine.

Prevention of hepatitis B virus (HBV) infection by vaccination can potentially eliminate HBV-related diseases. PreHevbrio™/PreHevbri® is a 3-antigen (S, preS1, preS2) HBV vaccine (3A-HBV) recently licensed for adults in the US, EU and Canada. This study evaluated antibody persistence in a subset of fully vaccinated and seroprotected (anti-HBs ≥ 10 mIU/mL) Finnish participants from the phase 3 trial (PROTECT) of 3A-HBV versus single-antigen HBV vaccine (1A-HBV).

Evaluation of Clinical Case Definitions for Respiratory Syncytial Virus Lower Respiratory Tract Infection in Young Children.

Background: Various case definitions of respiratory syncytial virus lower respiratory tract infection (RSV-LRTI) are currently proposed. We assessed the performance of 3 clinical case definitions against the World Health Organization definition recommended in 2015 (WHO 2015).

Methods: In this prospective cohort study conducted in 8 countries, 2401 children were followed up for 2 years from birth.

Mast cells selectively produce inflammatory mediators and impact the early response to reproductive tract infection.

Introduction: () is a Gram-negative obligate intracellular bacterium that causes reproductive tract complications in women, including ectopic pregnancies and tubal factor infertility. We hypothesized that mast cells, which are common at mucosal barriers, may contribute to responses to infection and aimed to define human mast cell responses to .

Methods: Human cord blood-derived mast cells (CBMCs) were exposed to to assess bacterial uptake, mast cell degranulation, gene expression, and production of inflammatory mediators.

Effect of viral storm in patients admitted to intensive care units with severe COVID-19 in Spain: a multicentre, prospective, cohort study.

Background: The contribution of the virus to the pathogenesis of severe COVID-19 is still unclear. We aimed to evaluate associations between viral RNA load in plasma and host response, complications, and deaths in critically ill patients with COVID-19.

Methods: We did a prospective cohort study across 23 hospitals in Spain.