Publications by authors named "Mark Loeb"

Background: A 2021 meta-analysis of 37 randomised controlled trials (RCTs) of vitamin D supplementation for prevention of acute respiratory infections (ARIs) revealed a statistically significant protective effect of the intervention (odds ratio [OR] 0·92 [95% CI 0·86 to 0·99]). Since then, six eligible RCTs have been completed, including one large trial (n=15 804). We aimed to re-examine the link between vitamin D supplementation and prevention of ARIs.

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Background: Oseltamivir is recommended for the treatment of adults hospitalized with influenza, but adherence is often suboptimal. This may be due to doubts about the reliability of the evidence supporting its benefits, particularly when initiation is delayed. We aimed to assess the effectiveness of oseltamivir in reducing mortality in older adults hospitalized with influenza, with a focus on the timing of initiation.

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Background: Hemagglutinin (HA)-inhibiting antibodies contribute to the immune defense against influenza infection. However, there are insufficient data on the extent of correlation between vaccine-elicited HA antibodies and protection in children against different influenza strains, particularly when comparing live attenuated influenza vaccines (LAIV) versus inactivated influenza vaccines (IIV).

Methods: We measured postvaccination hemagglutination-inhibition (HAI) titers in 3-15-year-old participants of a cluster-randomized controlled trial of trivalent LAIV(3) versus IIV(3) in Canadian Hutterite colonies.

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Background: Studies have shown an association between workplace safety climate scores and patient outcomes. This study aimed to investigate (1) performance of the hospital safety climate scale that was adapted to assess acute respiratory illness safety climate, (2) factors associated with safety climate scores, and (3) whether the safety scores were associated with following recommended droplet and contact precautions.

Methods: A survey of Canadian healthcare personnel participating in a cohort study of influenza during the 2010/2011-2013/2014 winter seasons.

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Background: Surgical site infections continue to be a significant challenge following colorectal surgery. These can result in extended hospital stays, hospital readmissions, increased treatment costs, and negative effects on patients' quality of life. Antibiotic prophylaxis plays a crucial role in preventing infection during surgery, specifically in preventing surgical site infections after colorectal surgery in adult patients.

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Background: The demand for COVID-19 vaccines has diminished as the pandemic lingers. Understanding vaccine hesitancy among essential workers is important in reducing the impact of future pandemics by providing effective immunization programs delivered expeditiously.

Method: Two surveys exploring COVID-19 vaccine acceptance in 2021 and 2022 were conducted in cohorts of health care providers (HCP) and education workers participating in prospective studies of COVID-19 illnesses and vaccine uptake.

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We evaluated the effectiveness of COVID-19 vaccines among South Asians living in Ontario, Canada compared to non-South Asians and compared the odds of symptomatic COVID-19 infection and related hospitalizations and deaths among non-vaccinated South Asians and non-South Asians. This was a test negative design study conducted in Ontario, Canada between December 14, 2020 and November 15, 2021. All eligible individuals >18 years with symptoms of COVID-19 were subdivided by ethnicity (South Asian vs other) and vaccination status (vaccinated versus not).

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Background: Influenza vaccination may protect through the humoral immune response, cellular immune response, or possibly both. Immunity after vaccination can be mediated through antibodies that may be detected by the rise of serum hemagglutination inhibition (HAI) titers. Our objective was to investigate the proportion of protection against influenza mediated through antibodies by measuring the rise of HAI titer (indirect effect) compared to that induced through other immune mechanisms (direct effect) for influenza A and B.

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Article Synopsis
  • The study investigates the best empiric antibiotic treatments for non-ventilator-associated hospital-acquired pneumonia (HAP) through a network meta-analysis of randomized controlled trials (RCTs).
  • It analyzed data from 39 RCTs with a total of 4,807 participants, suggesting that piperacillin-tazobactam and carbapenems may be more effective at reducing treatment failure compared to cephalosporins, though the certainty of this evidence is low.
  • Additionally, the analysis indicated that a combination of ceftazidime and linezolid did not significantly differ from using cephalosporins alone in terms of reducing all-cause mortality, also reflecting low
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Background: The cefazolin inoculum effect (CzIE) is a phenomenon whereby some MSSA isolates demonstrate resistance to cefazolin when a high bacterial inoculum is used for susceptibility testing. The clinical significance of this phenotypic phenomenon remains unclear. We conducted a systematic review to answer the following question: In patients with serious MSSA infection treated with cefazolin, does infection due to CzIE-positive MSSA isolates result in worse clinical outcomes than infection due to CzIE-negative MSSA isolates?

Methods: Ovid MEDLINE, Embase, Cochrane CENTRAL, medRxiv and bioRxiv were searched from inception until 12 April 2023.

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Background: The role of serologic testing for SARS-CoV-2 has evolved during the pandemic as seroprevalence in global populations has increased. The Infectious Diseases Society of America (IDSA) convened an expert panel to perform a systematic review of the coronavirus disease 2019 (COVID-19) serology literature and construct updated best practice guidance related to SARS-CoV-2 serologic testing. This guideline is an update to the fourth in a series of rapid, frequently updated COVID-19 guidelines developed by IDSA.

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Article Synopsis
  • The WHO Model List of Essential Medicines (EML) focuses on prioritizing medicines that are crucial for global public health, particularly in the context of antibiotic use and resistance.
  • In response to the rise of antimicrobial resistance, the EML introduced a new classification system called AWaRe, which categorizes antibiotics into Access, Watch, and Reserve groups to guide appropriate usage.
  • The 2023 AWaRe classification includes 41 essential antibiotics and aims to enhance global antibiotic prescribing practices, promoting the use of Access antibiotics to optimize treatment and reduce misuse to prolong the effectiveness of these medications.
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There are limited data on individual risk factors for SARS-CoV-2 infection (including unrecognized infection). In this seroepidemiologic substudy of an ongoing prospective cohort study of community-dwelling adults, participants were thoroughly characterized pre-pandemic. The SARS-CoV-2 infection was ascertained by serology.

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Accurate molecular diagnostic tests are necessary for confirming a diagnosis of coronavirus disease 2019 (COVID-19) and for identifying asymptomatic carriage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The number of available SARS-CoV-2 nucleic acid detection tests continues to increase as does the COVID-19 diagnostic literature. Thus, the Infectious Diseases Society of America (IDSA) developed an evidence-based diagnostic guideline to assist clinicians, clinical laboratorians, patients, and policymakers in decisions related to the optimal use of SARS-CoV-2 nucleic acid amplification tests.

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Objectives: Combining multivariate and network meta-analysis methods simultaneously in a multivariate network meta-analysis (MVNMA) provides the methodological framework to analyze the largest amount of evidence relevant to decision-makers (i.e., from indirect evidence and correlated outcomes).

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Introduction: There are limited data on the longitudinal impact of Lyme disease. Predictors of recovery have not been fully established using validated data collection instruments. There are sparse data on the immunological response to infection over time.

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Background: Residents in long-term care homes, who tend to be of advanced age and frail, are at increased risk of respiratory infections. The respiratory microbiota is known to change with age, but whether these changes contribute to the risk of infection is not known. Our goal was to determine how the nasal microbiota of frail older adults changes during symptoms of influenza-like illness (ILI) and how this may be impacted by enrolment in a placebo-controlled trial testing the feasibility of administering a GG probiotic to prevent respiratory infection (2014-2017).

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More than a decade after the Consolidated Standards of Reporting Trials group released a reporting items checklist for non-inferiority randomized controlled trials, the infectious diseases literature continues to underreport these items. Trialists, journals, and peer reviewers should redouble their efforts to ensure infectious diseases studies meet these minimum reporting standards.

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Background: Influenza vaccines prevent influenza-related morbidity and mortality; however, suboptimal vaccine effectiveness (VE) of non-adjuvanted trivalent inactivated influenza vaccine (naTIV) or quadrivalent formulations in older adults prompted the use of enhanced products such as adjuvanted TIV (aTIV). Here, the VE of aTIV is compared to naTIV for preventing influenza-associated hospitalization among older adults.

Methods: A test-negative design study was used with pooled data from the 2012 to 2015 influenza seasons.

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Background And Objective: To identify COVID-19 actionable statements (e.g., recommendations) focused on specific disadvantaged populations in the living map of COVID-19 recommendations (eCOVIDRecMap) and describe how health equity was assessed in the development of the formal recommendations.

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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.

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Introduction: Airway disease exacerbations are cyclical related to respiratory virus prevalence. The COVID-19 pandemic has been associated with reduced exacerbations possibly related to public health measures and their impact on non-COVID-19 respiratory viruses. We aimed to investigate the prevalence of non-COVID-19 respiratory viruses during the pandemic compared with prior in Ontario, Canada and healthcare utilisation related to asthma, chronic obstructive pulmonary disease (COPD) and respiratory tract infection.

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