Estimated Protection of Prior SARS-CoV-2 Infection Against Reinfection With the Omicron Variant Among Messenger RNA-Vaccinated and Nonvaccinated Individuals in Quebec, Canada.

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.

Role of high-risk antibiotic use in incidence of health-care-associated Clostridioides difficile infection in Quebec, Canada: a population-level ecological study.

Background: The incidence of health-care-associated Clostridioides difficile infections has been declining in the Canadian province of Quebec since 2015. We examined whether changes in high-risk antibiotic use could account for this decrease, as reported in other jurisdictions.

Methods: We did a retrospective interrupted time-series analysis of 12 hospitals in the Canadian province of Quebec, representing a quarter of all health-care-associated C difficile infections in this region between April 1, 2012, and March 31, 2017.

Two-Dose Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Effectiveness With Mixed Schedules and Extended Dosing Intervals: Test-Negative Design Studies From British Columbia and Quebec, Canada.

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.

Increased Community-Associated Clostridioides difficile Infections in Quebec, Canada, 2008-2015.

The annual incidence rate of community-associated Clostridioides difficile infections in Quebec, Canada, has increased by 33.3%, from 0.51 (2008) to 0.

Impact of Isolating Clostridium difficile Carriers on the Burden of Isolation Precautions: A Time Series Analysis.

Background: The isolation of asymptomatic Clostridium difficile (CD) carriers may decrease the incidence of hospital-associated C. difficile infections (CDI), but its impact on isolation precaution needs is unknown.

Methods: A time series analysis was conducted to investigate the impact of isolating CD carriers on the burden of isolation precautions from 2008 to 2016 in a Canadian hospital.