Publications by authors named "Wals P"

Article Synopsis
  • The text discusses the impact of pneumococcal conjugate vaccines (PCVs), specifically PCV10 and PCV13, on invasive pneumococcal disease (IPD) globally, highlighting how these vaccines have reduced the prevalence of disease caused by vaccine-type serotypes after extensive use.
  • It describes the methodology of data collection from various surveillance sites, which aimed to evaluate IPD cases that occurred five years after the vaccines were implemented, focusing on different age groups for analysis.
  • Findings indicate significant differences in serotype distribution between PCV10 and PCV13 sites; notably, certain serotypes, such as 19A and serotype 3, were prevalent in specific age groups, signaling ongoing challenges in controlling
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Background: Pneumococcal conjugate vaccines (PCVs) that are ten-valent (PCV10) and 13-valent (PCV13) became available in 2010. We evaluated their global impact on invasive pneumococcal disease (IPD) incidence in all ages.

Methods: Serotype-specific IPD cases and population denominators were obtained directly from surveillance sites using PCV10 or PCV13 in their national immunisation programmes and with a primary series uptake of at least 50%.

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In the province of Quebec, Canada, a 2 + 1 dose pneumococcal conjugate vaccine (PCV) program for children was implemented in 2004. PCV7, PCV10, PCV13 and a mixed PCV10/PCV13 schedule were sequentially used without catch-up. The effectiveness of vaccination schedules to prevent serotype 19A invasive pneumococcal disease (IPD) in <5-year-old children was estimated by the indirect cohort method during 2009-2023.

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Objective: To identify recent trends in invasive meningococcal diseases (IMD) in Quebec, Canada, with a focus on MenY cases and MenY strains.

Methods: IMD cases and MenY strains from January 1, 2015 to August 11, 2023 were analyzed for clonal analysis and prediction of susceptibility to MenB vaccines. MenY strains of ST-23 CC from Quebec were analyzed with global MenY strains by core-genomic multi-locus sequence typing (cg-MLST).

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Background: The new 15- and 20-valent pneumococcal conjugate vaccines (PCV15 and PCV20) have been marketed on the basis of immunogenicity criteria, one of them being a non-inferior response as compared with the 13-valent vaccine (PCV13). In the past, PCV13 was also authorized on the basis of the same criteria, using the 7-valent vaccine (PCV7) as a reference.

Methods: Our aim was to compare the immunogenicity of these three vaccines in toddlers.

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Evidence on the protective effect of influenza vaccines to prevent cardiovascular disease (CVD) is mounting. We identified 28 systematic reviews/meta-analyses on the effect of influenza vaccines on CVD using different research questions, data sources, selection criteria and outcomes. Most results leaned towards a protective effect.

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Streptococcus pneumoniae serotype 19A is a highly diverse, often antimicrobial-resistant Gram-positive bacterium which can cause invasive pneumococcal disease (IPD). In 2021, public health authorities in the Canadian province of Québec observed an increase of serotype 19A IPD in children <5 years. The purpose of this study was to determine the clonal composition of serotype 19A isolates collected from this age group in Québec, from 2016 to 2021.

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In the province of Quebec, Canada, a 2 + 1 dose pneumococcal conjugate vaccine (PCV) program for children was implemented in 2004. PCV7 was replaced by PCV10 in 2009, by PCV13 in 2011 and by PCV10 in 2018, without catch-up in all instances. The objective was to estimate PCV13 effectiveness to prevent serotype 3 invasive pneumococcal disease in children aged less than 5 years, using 2010-2018 mandatory notification and laboratory surveillance data, an indirect cohort design and multivariate logistic regression models.

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Background: Older adults (aged ≥60 years) were prioritised for COVID-19 booster vaccination due to severe outcome risk, but the risk for this group is also affected by previous SARS-CoV-2 infection and vaccination. We estimated vaccine effectiveness against omicron-associated hospitalisation in older adults by previously documented infection, time since last immunological event, and age group.

Methods: This was a population-based test-negative case-control study done in Quebec, Canada, during BA.

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Background: Respiratory viruses have been previously suspected to trigger invasive pneumococcal disease (IPD). After progressive non-pharmaceutical interventions (NPI) lifting, an unusual RSV outbreak has been observed in the Fall 2021, raising concerns about the possible consequences on IPD. We aimed to analyse the evolution of IPD incidence across age-groups since NPI lifting, and its temporal association with respiratory viral infections.

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Objectives: This study aimed to examine the factors associated with low sugar-sweetened beverage (SSB) consumption and intention to avoid these products as well as investigate the role of different types of social norms in the adoption of this behaviour.

Study Design: This study reports the results of a secondary data analysis from a cross-sectional telephone survey.

Methods: A total of 1000 adults were randomly recruited in the province of Québec, Canada, using a random-digit dialling procedure.

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This review summarizes the recent Global Meningococcal Initiative (GMI) regional meeting, which explored meningococcal disease in North America. Invasive meningococcal disease (IMD) cases are documented through both passive and active surveillance networks. IMD appears to be decreasing in many areas, such as the Dominican Republic (2016: 18 cases; 2021: 2 cases) and Panama (2008: 1 case/100,000; 2021: <0.

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Importance: The Omicron variant is phylogenetically and antigenically distinct from earlier SARS-CoV-2 variants and the original vaccine strain. Protection conferred by prior SARS-CoV-2 infection against Omicron reinfection, with and without vaccination, requires quantification.

Objective: To estimate the protection against Omicron reinfection and hospitalization conferred by prior heterologous non-Omicron SARS-CoV-2 infection and/or up to 3 doses of an ancestral, Wuhan-like messenger RNA (mRNA) vaccine.

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Article Synopsis
  • The study investigates the effectiveness of prior SARS-CoV-2 infections and mRNA vaccinations in providing immunity against the omicron subvariant BA.2 among health-care workers in Quebec, Canada, during its peak period from March to June 2022.
  • It uses a test-negative case-control design to compare cases (those who tested positive for BA.2) and controls (those who tested negative) while also considering various vaccination statuses.
  • Findings indicate that previous infection with earlier SARS-CoV-2 strains (particularly pre-omicron) reduces the risk of BA.2 infection by about 38%, with even greater protection seen in those who were also vaccinated.
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Background: Residents of long-term care facilities (LTCFs) and private residences for seniors (PRSs) were given priority for vaccination against coronavirus disease 2019 (COVID-19). Given the shortage of vaccine in the winter of 2021, the recommended postponing the administration of second doses to ensure more rapid and widespread administration of first doses. The objective of this study was to measure the impact of first-dose vaccination on 1) the incidence of cases and complications in LTCFs and PRSs and 2) the frequency of outbreaks in LTCFs.

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Background: One hundred years ago, Albert Calmette developed an avirulent strain of Mycobacterium bovis, but there is no evidence that his BCG strain was more immunogenic than wild-type M. bovis. Geographic variations in BCG efficacy remain ill-understood.

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Background: The Canadian coronavirus disease 2019 (COVID-19) immunization strategy deferred second doses and allowed mixed schedules. We compared 2-dose vaccine effectiveness (VE) by vaccine type (mRNA and/or ChAdOx1), interval between doses, and time since second dose in 2 of Canada's larger provinces.

Methods: Two-dose VE against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or hospitalization among adults ≥18 years, including due to Alpha, Gamma, and Delta variants of concern (VOCs), was assessed ≥14 days postvaccination by test-negative design studies separately conducted in British Columbia and Quebec, Canada, between 30 May and 27 November (epi-weeks 22-47) 2021.

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Invasive meningococcal disease (IMD) causes significant morbidity and mortality worldwide with serogroup B being the predominant serogroup in Australia and other countries for the past few decades. The licensed 4CMenB vaccine is effective in preventing meningococcal B disease. Emerging evidence suggests that although 4CMenB impact on carriage is limited, it may be effective against gonorrhoea due to genetic similarities between .

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Background: We carried out a case-control study that examined whether receipt of the inactivated influenza vaccine during the 2019-2020 season impacted on the risk of coronavirus disease 2019 (COVID-19), as there was a concern that the vaccine could be detrimental through viral interference.

Methods: A total of 920 cases with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (diagnosed between March and October 2020) and 2,123 uninfected controls were recruited from those who were born in Québec between 1956 and 1976 and who had received diagnostic services at two hospitals (Montréal and Sherbrooke, Québec). After obtaining consent, a questionnaire was administered by phone.

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Background: Early in the coronavirus disease 2019 (COVID-19) pandemic, before severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines became available, it was hypothesized that BCG (Bacillus Calmette-Guérin), which stimulates innate immunity, could provide protection against SARS-CoV-2. Numerous ecological studies, plagued by methodological deficiencies, revealed a country-level association between BCG use and lower COVID-19 incidence and mortality. We aimed to determine whether BCG administered in early life decreased the risk of SARS-CoV-2 infection in adulthood and the severity of COVID-19.

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Background: In Canada, first and second doses of messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were uniquely spaced 16 weeks apart. We estimated 1- and 2-dose mRNA vaccine effectiveness (VE) among healthcare workers (HCWs) in Québec, Canada, including protection against varying outcome severity, variants of concern (VOCs), and the stability of single-dose protection up to 16 weeks postvaccination.

Methods: A test-negative design compared vaccination among SARS-CoV-2 test-positive and weekly matched (10:1), randomly sampled, test-negative HCWs using linked surveillance and immunization databases.

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Article Synopsis
  • 4CMenB is a vaccine effective against invasive meningococcal disease caused by capsular group B, and data from 7 countries shows it significantly reduces cases in various age groups and settings.
  • Real-world evidence indicates that receiving at least 2 doses can lower MenB cases by 50%-100% in individuals aged 2 months to 20 years, with reported effectiveness ranging from 59%-100% for fully vaccinated individuals.
  • The consistent safety profile of 4CMenB and its demonstrated effectiveness highlights its crucial role in preventing MenB disease, especially through routine vaccinations for infants, young children, and adolescents.
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Article Synopsis
  • The PSERENADE project focuses on global surveillance of invasive pneumococcal disease (IPD) to assess the impact of pneumococcal conjugate vaccines (PCV10/13).
  • Among 138 countries using PCV10/13 as of 2018, 109 had IPD surveillance systems, with data collected from 76, enabling a comprehensive analysis of 240,639 post-vaccine IPD cases.
  • The dataset will aid in understanding the effectiveness of the vaccines across different demographics and vaccination schedules, influencing future immunization policies globally and nationally.
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