Vaccine

It is recognised that many observational studies and randomised control trials reporting high efficacy for Covid-19 vaccines suffer from various biases. Systematic review identified thirty-seven studies that suffered from one particular and serious form of bias called miscategorisation bias, whereby study participants who have been vaccinated are categorised as unvaccinated up to and until some arbitrarily defined time after vaccination occurred. Simulation demonstrates that this miscategorisati...

BackgroundIncomplete vaccination in Australia is greatly due to vaccine hesitancy, which is driven by multiple factors. Studies analysing the effect of behavioural nudges on vaccine uptake have shown promising results. Although there is some evidence for positively framed SMS vaccine messages, evidence is lacking for loss-based framed messages which may be highly effective but may paradoxically risk increasing vaccine hesitancy. This pilot study aimed to evaluate the effect of loss-based framed...

BackgroundRoutine childhood vaccination improves health and prevents morbidity and mortality from vaccination preventable diseases. There are indications that the COVID-19 pandemic has negatively impacted vaccination rates globally, but systematic studies on this are still lacking in Canada. This study aims to add knowledge on the effect of the pandemic on pneumococcal vaccination rates of children using self-reported immunization data entered into the CANImmunize digital vaccination tool. Meth...

BackgroundEstimating attributable risk (AR) through self-controlled case series (SCCS) analyses alone may limit generalizability because SCCS only incorporate vaccinated patients with the outcome (e.g., Guillain-Barre syndrome [GBS]) who may differ from the overall population recommended for vaccination. ObjectiveWe aimed to demonstrate background event incidence rates impact on vaccine-specific GBS ARs and to standardize ARs across different vaccine studies by applying a generalizable, populat...

Background and ObjectivesCOVID-19 vaccine was first recommended for children ages 5-11 years on November 2, 2021. This report describes COVID-19 vaccination coverage and parental intent to vaccinate their child ages 5-11 years, overall, by sociodemographic characteristics, and by social and behavioral drivers of vaccination, the fourth month after recommendation. MethodsWe analyzed data from 5,438 interviews conducted in February 2022 from the National Immunization Survey-Child COVID Module (NI...

ObjectivesOur aim was to measure COVID-19 vaccine uptake among children aged 5-17 years old via parents participating in the CHASING COVID Cohort and identify sociodemographic factors associated with it. MethodsIn this longitudinal study, parents of school-aged children were asked about their own vaccination status and that of their children at three time points between June 2021-January 2022, along with reasons for vaccinating immediately or delaying vaccinations for their children. Multivaria...

Participants in studies investigating COVID-19 vaccines commonly report reactogenicity events, and concerns about side effects may lead to reluctance to receive updated COVID-19 vaccinations. A real-world, post hoc analysis, observational 2019nCoV-406 study, was conducted to examine reactogenicity within the first 2 days after vaccination with either a protein-based vaccine (NVX-CoV2373) or an mRNA vaccine (BNT162b2 or mRNA-1273) in individuals who previously completed a primary series. Propensi...

BackgroundVaccines are highly effective for preventing a range of childhood infections. However, there have been concerns about an alarming decline in vaccinations in 2020 due to the COVID-19 pandemic. MethodsWe performed a rapid review for studies that assessed childhood vaccination uptake during restrictive phases of the COVID-19 pandemic. ResultsWe found 35 published studies that compared changes in the pattern of childhood vaccinations before and during the pandemic. Thirteen were surveys;...

A second dose deferred strategy has been proposed to increase initial population immunity as an alternative to the default two dose vaccine regimen with spacing of 21 or 28 days between vaccine doses for the mRNA vaccines from Pfizer and Moderna. This increased initial population immunity is only of value if one dose immunity does not decay so fast as to nullify the benefit. Because decay rates of one dose and two dose efficacy are currently unknown, a model to project population immunity betwee...

BackgroundVaccination helps prevent SARS-CoV-2 infection and severe COVID-19. However, vaccine-induced humoral immune responses vary among individuals and wane over time. We aimed to describe the SARS-CoV-2 anti-spike IgG antibody response to vaccination and identify health and demographic factors associated with this response among children and adults. MethodsWe studied a subset of double-vaccinated children (n= 151; mean age: 12 {+/-}1.5 years, 46% female) and adults (n= 995; 44 {+/-}6.0 year...

BackgroundCOVID-19 vaccines are well-established as safe. However, continued surveillance of COVID-19 vaccines is important to ensure the safety of newly formulated vaccines. This study evaluated the association between vaccination with 2023-2024 formula COVID-19 vaccines and multiple health outcomes among Medicare beneficiaries aged 65 years and older in the United States. MethodsThe study used health plan data from the Medicare Fee-for-Service (FFS) claims database and extended from September...

BackgroundCOVID-19 restrictions and its impact on healthcare resources have reduced routine infant vaccine uptake, although some report that this effect was short-lived. These prior studies mostly described entire populations, but disparities in uptake may have changed during the pandemic due to differential access to healthcare. ObjectivesWe aimed to examine disparities in the reduction in routine infant vaccine uptake during the COVID-19 pandemic in Manitoba, Canada. MethodsWe assessed vacci...

BackgroundIn most high-income countries, infant vaccination with acellular pertussis (aP) vaccines is the standard of care for the prevention of pertussis disease. Based on immunological and epidemiological evidence, we hypothesised that substitution of the first aP dose in the vaccination schedule with whole-cell (wP) vaccine might protect against the development of IgE-mediated food allergy. Here we report the results of a randomised comparison of the reactogenicity, immunogenicity, and IgE-me...

Background and ObjectivesIn Alberta, Canada, the COVID-19 vaccination program for children aged 5-11 years opened on November 26, 2021. Our objectives were to determine the cumulative vaccine coverage, stratified by age, during the first seven months of vaccine availability, and investigate factors associated with vaccine uptake. MethodsThis retrospective cohort study used population-based administrative health data to assess COVID-19 vaccination coverage among children aged 5-11 years in Alber...

BackgroundPneumococcal conjugate vaccines (PCVs) cover only a proportion of disease-causing serotypes. In some settings, population-level introduction of PCVs has resulted in an increase in "non-vaccine" serotype incidence. Higher-valency PCVs were developed to address shifting disease-causing serotypes. We aim to systematically define the trends in vaccine immunogenicity and likely protection over time. MethodsWe conducted a systematic review and meta-analysis of studies published to Jan 7, 20...

BackgroundWhole-cell pertussis (wP) and acellular pertussis (aP) vaccines evoke different immune responses to pertussis vaccine antigens. We compared the effect of a heterologous wP/aP/aP primary series (hereafter mixed wP/aP) versus a homologous aP/aP/aP primary schedule (hereafter aP-only) on antibody responses to co-administered vaccine antigens in infants and toddlers. MethodsWe randomised Australian infants in a 1:1 ratio to receive either a mixed wP/aP schedule (pentavalent diphtheria-tet...

ImportanceCOVID-19 vaccines are authorized for use in children in the United States; real-world assessment of vaccine effectiveness in children is needed. ObjectiveTo estimate the effectiveness of receiving a complete primary series of monovalent BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine in US children. DesignA cohort study of children aged 5-17 years vaccinated with BNT162b2 matched with unvaccinated children. SettingParticipants identified in Optum and CVS Health insurance administrative ...

ObjectivesTo compare the efficacy of influenza vaccines of any valency for adults 60 years and older. MethodsO_ST_ABSDesignC_ST_ABSSystematic review with network meta-analysis (NMA) Information sourcesMEDLINE, EMBASE, JBI Evidence-Based Practice (EBP) Database, PsycINFO, and Cochrane Evidence Based Medicine database from inception to June 20, 2022. Eligibility criteriaRandomized controlled trials (RCTs) including older adults ([≥]60 years old) receiving an influenza vaccine licensed in Can...

Vaccination is a key tool to mitigate impacts of the COVID-19 pandemic. In Israel, COVID-19 vaccines became available to adults in December 2020 and to 5-11-year-old children in November 2021. Ahead of the vaccine roll-out in children, we aimed to determine whether surveyed parents intended to vaccinate their children and describe reasons for their intentions. We collected information on parental socio-demographic characteristics, COVID-19 vaccine history, intention to vaccinate their children a...

BackgroundVarious COVID-19 vaccines with proven safety and effectiveness are available now but vaccine hesitancy remains a public threat. COVID-19 vaccines uptake appears to have an essential role in the successful control of the COVID-19 pandemic. ObjectiveTo examine predictors of COVID-19 vaccination uptake and reasons for decline of vaccination. MethodsWe followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines for this systematic review. We searched Medlin...