Effectiveness of Influenza Vaccination During Pregnancy Against Laboratory-Confirmed Seasonal Influenza Among Infants Under 6 Months of Age in Ontario, Canada.

Background: Randomized trials conducted in low- and middle-income settings demonstrated efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age. However, vaccine effectiveness (VE) estimates from settings with different population characteristics and influenza seasonality remain limited.

Methods: We conducted a test-negative study in Ontario, Canada.

Measuring waning protection from seasonal influenza vaccination during nine influenza seasons, Ontario, Canada, 2010/11 to 2018/19.

BackgroundWaning immunity from seasonal influenza vaccination can cause suboptimal protection during peak influenza activity. However, vaccine effectiveness studies assessing waning immunity using vaccinated and unvaccinated individuals are subject to biases.AimWe examined the association between time since vaccination and laboratory-confirmed influenza to assess the change in influenza vaccine protection over time.

Estimating the Incidence of First RSV Hospitalization in Children Born in Ontario, Canada.

Background: Respiratory syncytial virus (RSV) contributes significantly to morbidity in children, placing substantial burdens on health systems, thus RSV vaccine development and program implementation are a public health priority. More data on burden are needed by policymakers to identify priority populations and formulate prevention strategies as vaccines are developed and licensed.

Methods: Using health administrative data, we calculated incidence rates of RSV hospitalization in a population-based birth cohort of all children born over a six-year period (May 2009 to June 2015) in Ontario, Canada.

Evaluating the Impact of Statin Use on Influenza Vaccine Effectiveness and Influenza Infection in Older Adults.

Background: Older adults are recommended to receive influenza vaccination annually, and many use statins. Statins have immunomodulatory properties that might modify influenza vaccine effectiveness (VE) and alter influenza infection risk.

Methods: Using the test-negative design and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against laboratory-confirmed influenza among community-dwelling statin users and nonusers aged ≥66 years during the 2010-2011 to 2018-2019 influenza seasons.

Influenza Vaccine Effectiveness Against All-Cause Mortality Following Laboratory-Confirmed Influenza in Older Adults, 2010-2011 to 2015-2016 Seasons in Ontario, Canada.

Background: Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza.

Methods: Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-cause mortality following laboratory-confirmed influenza for community-dwelling adults aged >65 years during the 2010-2011 to 2015-2016 influenza seasons.

The impact of repeated vaccination using 10-year vaccination history on protection against influenza in older adults: a test-negative design study across the 2010/11 to 2015/16 influenza seasons in Ontario, Canada.

IntroductionAnnual influenza vaccination is recommended for older adults, but evidence regarding the impact of repeated vaccination has been inconclusive.AimWe investigated vaccine effectiveness (VE) against laboratory-confirmed influenza and the impact of repeated vaccination over 10 previous seasons on current season VE among older adults.MethodsWe conducted an observational test-negative study in community-dwelling adults aged > 65 years in Ontario, Canada for the 2010/11 to 2015/16 seasons by linking laboratory and health administrative data.

Influenza Vaccine Effectiveness in Preventing Hospitalizations in Older Patients With Chronic Obstructive Pulmonary Disease.

Background: Annual influenza immunization is recommended for people with chronic obstructive pulmonary disease (COPD) by all major COPD clinical practice guidelines. We sought to determine the seasonal influenza vaccine effectiveness (VE) against laboratory-confirmed influenza-associated hospitalizations among older adults with COPD.

Methods: We conducted a test-negative study of influenza VE in community-dwelling older adults with COPD in Ontario, Canada using health administrative data and respiratory specimens collected from patients tested for influenza during the 2010-11 to 2015-16 influenza seasons.

Influenza Vaccine Effectiveness Among Patients With Cancer: A Population-Based Study Using Health Administrative and Laboratory Testing Data From Ontario, Canada.

Purpose: Seasonal influenza vaccination is recommended for patients with cancer despite concerns of disease or treatment-associated immunosuppression. The objective of this study was to evaluate vaccine effectiveness (VE) against laboratory-confirmed influenza for patients with cancer.

Patients And Methods: We conducted an observational test-negative design study of previously diagnosed patients with cancer 18 years of age and older who underwent influenza testing during the 2010-2011 to 2015-2016 influenza seasons in Ontario, Canada.

Can routinely collected laboratory and health administrative data be used to assess influenza vaccine effectiveness? Assessing the validity of the Flu and Other Respiratory Viruses Research (FOREVER) Cohort.

Background: Linking data on laboratory specimens collected during clinical practice with health administrative data permits highly powered vaccine effectiveness (VE) studies to be conducted at relatively low cost, but bias from using convenience samples is a concern. We evaluated the validity of using such data for estimating VE.

Methods: We created the Flu and Other Respiratory Viruses Research (FOREVER) Cohort by linking individual-level data on respiratory virus laboratory tests, hospitalizations, emergency department visits, and physician services.

Characteristics and Outcomes of Young Children Hospitalized With Laboratory-confirmed Influenza or Respiratory Syncytial Virus in Ontario, Canada, 2009-2014.

Background: Respiratory illnesses are a major contributor to pediatric hospitalizations, with influenza and respiratory syncytial virus (RSV) causing substantial morbidity and cost each season. We compared the characteristics and outcomes of children 0-59 months of age who were hospitalized with laboratory-confirmed influenza or RSV between 2009 and 2014 in Ontario, Canada.

Methods: We included hospitalized children who were tested for influenza A, influenza B and RSV and were positive for a single virus.

Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection.

Background: Acute myocardial infarction can be triggered by acute respiratory infections. Previous studies have suggested an association between influenza and acute myocardial infarction, but those studies used nonspecific measures of influenza infection or study designs that were susceptible to bias. We evaluated the association between laboratory-confirmed influenza infection and acute myocardial infarction.

Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada.

Uncertainty remains regarding the magnitude of effectiveness of influenza vaccines for preventing serious outcomes, especially among young children. We estimated vaccine effectiveness (VE) against laboratory-confirmed influenza hospitalizations among children aged 6-59 months. We used the test-negative design in hospitalized children in Ontario, Canada during the 2010-11 to 2013-14 influenza seasons.

Miller Fisher syndrome in a toddler with influenza A (pH1N1) infection.

A 17-month-old previously healthy child presented with a 2-day history of inability to fully open his eyes and slight gait ataxia. In the month preceding admission, he had had low grade, intermittent fevers, followed by a nonproductive cough and sneezing. During hospital admission he lost deep tendon reflexes and was unable to walk.

High incidence of penicillin resistance among alpha-hemolytic streptococci isolated from the blood of children with cancer.

Objectives: To survey the susceptibility profiles to several beta-lactam antibiotics and to identify factors related to resistance among blood isolates of alpha-hemolytic streptococci (AHS) obtained from children with cancer.

Study Design: All pediatric oncology patients with AHS bacteremia occurring from January 1996 through June 1999 at one cancer center were identified. Isolates were categorized based on the minimum inhibitory concentration as susceptible, intermediate, or resistant to several beta-lactam antibiotics.