Characteristics and clinical outcomes of nirmatrelvir/ritonavir (PaxlovidTM) recipients in Canada, 2022: a descriptive cohort study.

Background: Nirmatrelvir/ritonavir (N/R) (PaxlovidTM) was introduced in Canada in January 2022. This was the first oral coronavirus disease 2019 (COVID-19) antiviral therapy that was deployed on a large scale in Canada. Since N/R was a new therapeutic option to reduce severe outcomes in high-risk populations, clinical and implementation questions were raised about its real-world utilization and impact. The objective of this retrospective observational study was to describe the characteristics and clinical outcomes of recipients of N/R in the first several months of its availability in Canada, during the Omicron wave. Methods: Provincial summary data were pooled together for the analysis. Descriptive statistics were used to explore the characteristics and clinical outcomes of the recipients. Pearson's Chi-square test and unadjusted odds ratio along with 95% confidence intervals were used to identify the potential risk factors for severe outcomes. Data were generally collected between January and September 2022. Results: Seventy-six percent of N/R recipients were 60 years of age and older and 56% were female. Eighty-four percent of recipients had received three or more COVID-19 vaccinations and 67% had comorbidities. All-cause severe 30-day outcomes were uncommon, with 0.4% reported as deceased, 0.1% admitted to the intensive care unit and 2.0% hospitalized after N/R administration. Risk factors statistically associated with severe outcomes were immunosuppression, comorbidities, age of 60 years and older, and being unvaccinated. Conclusion: In the first months of its availability in Canada, N/R was mostly used in vaccinated patients 60 years and older with one or more comorbidities. Severe outcomes in N/R recipients were uncommon and mostly reported in patients with risk factors.

A framework for the systematic consideration of ethics, equity, feasibility, and acceptability in vaccine program recommendations.

For the successful implementation of population-level recommendations, it is critical to consider the full spectrum of public health science, including clinical and programmatic factors. Current frameworks may identify various factors that should be examined when making evidence-informed vaccine-related recommendations. However, while most immunization guidelines systematically assess clinical factors, such as efficacy and safety of vaccines, there is no published framework outlining how to systematically assess programmatic factors, such as the ethics, equity, feasibility, and acceptability of recommendations. We have addressed this gap with the development of the EEFA (Ethics, Equity Feasibility, Acceptability) Framework, supported by evidence-informed tools, including Ethics Integrated Filters, Equity Matrix, Feasibility Matrix, and an Acceptability Matrix. The Framework and tools are based on five years of environmental scans, systematic reviews and surveys, and refined by expert and stakeholder consultations and feedback. For each programmatic factor, the EEFA Framework summarizes the minimum threshold for consideration and when further in-depth analysis may be required, which aspects of the factor should be considered, how to assess the factor using the supporting evidence-informed tools, and who should be consulted to complete the assessment. Research, particularly in the fields of vaccine acceptability and equity, has validated the utility and comprehensiveness of the tools. The Framework has been successfully used in Canada for clear, timely, transparent vaccine guidance with positive stakeholder feedback on its comprehensiveness, relevance and appropriateness. Applying the EEFA Framework allows for the systematic consideration of the spectrum of public health science without a delay in recommendations, complementing existing decision-making frameworks. This Framework will therefore be useful for advisory groups worldwide to integrate critical factors that could impact the successful and timely implementation of comprehensive, transparent recommendations, and will further the global objective of developing practical and evidence-informed immunization policies.

Trends in vaccine-induced immunity to hepatitis B among Canadian street-involved youth.

In Canada, universal and publicly funded hepatitis B immunization programs have been available since 1998 in all provinces and territories. This present study estimates the proportion of having vaccine-induced immunity to hepatitis B virus (HBV) infection and its associated determinants among street-involved youth aged at 15-24 years old in Canada using the data collected by the Enhanced Surveillance of Canadian Street Youth. Vaccine-induced immunity was identified by blood test results of anti-HBc negative and anti-HBs positive. Of the 4,035 participants included in this study, the overall proportion of those with vaccine-induced immunity to HBV was 51.7% during the study period compared to over 90% among the general adolescent population. The proportion of street-involved youth immunized with HBV vaccine increased from 34.7% in 1999 to 64.4% in 2005. Immunity was higher among females (aOR = 1.43, 1.17-1.75) and among those with a reported history of sexually transmitted infection (aOR = 1.30, 1.03-1.63). The proportion of youth with the immunity decreased as age increased (aOR = 0.78, 0.76-0.81, per year increase). Despite an overall increase in the proportion of Canadian street-involved youth with vaccine-induced immunity to HBV, the proportion was still significantly lower than that observed in the general adolescent population. This highlights the need to improve the access to basic health care and the immunization programs to HBV for street-involved youth through creative outreach programs and other multi-faceted approaches.