Effectiveness of Influenza Vaccination During Pregnancy Against Laboratory-Confirmed Seasonal Influenza Among Infants Under 6 Months of Age in Ontario, Canada.

BACKGROUND: Randomized trials conducted in low- and middle-income settings demonstrated efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age. However, vaccine effectiveness (VE) estimates from settings with different population characteristics and influenza seasonality remain limited. METHODS: We conducted a test-negative study in Ontario, Canada. All influenza virus tests among infants <6 months from 2010 to 2019 were identified and linked with health databases to ascertain information on maternal-infant dyads. VE was estimated from the odds ratio for influenza vaccination during pregnancy among cases versus controls, computed using logistic regression with adjustment for potential confounders. RESULTS: Among 23 806 infants tested for influenza, 1783 (7.5%) were positive and 1708 (7.2%) were born to mothers vaccinated against influenza during pregnancy. VE against laboratory-confirmed infant influenza infection was 64% (95% confidence interval [CI], 50%-74%). VE was similar by trimester of vaccination (first/second, 66% [95% CI, 40%-80%]; third, 63% [95% CI, 46%-74%]), infant age at testing (0 to <2 months, 63% [95% CI, 46%-75%]; 2 to <6 months, 64% [95% CI, 36%-79%]), and gestational age at birth (≥37 weeks, 64% [95% CI, 50%-75%]; < 37 weeks, 61% [95% CI, 4%-86%]). VE against influenza hospitalization was 67% (95% CI, 50%-78%). CONCLUSIONS: Influenza vaccination during pregnancy offers effective protection to infants <6 months, for whom vaccines are not currently available.

Measuring waning protection from seasonal influenza vaccination during nine influenza seasons, Ontario, Canada, 2010/11 to 2018/19.

BackgroundWaning immunity from seasonal influenza vaccination can cause suboptimal protection during peak influenza activity. However, vaccine effectiveness studies assessing waning immunity using vaccinated and unvaccinated individuals are subject to biases.AimWe examined the association between time since vaccination and laboratory-confirmed influenza to assess the change in influenza vaccine protection over time.MethodsUsing linked laboratory and health administrative databases in Ontario, Canada, we identified community-dwelling individuals aged ≥ 6 months who received an influenza vaccine before being tested for influenza by RT-PCR during the 2010/11 to 2018/19 influenza seasons. We estimated the adjusted odds ratio (aOR) for laboratory-confirmed influenza by time since vaccination (categorised into intervals) and for every 28 days.ResultsThere were 53,065 individuals who were vaccinated before testing for influenza, with 10,264 (19%) influenza-positive cases. The odds of influenza increased from 1.05 (95% CI: 0.91-1.22) at 42-69 days after vaccination and peaked at 1.27 (95% CI: 1.04-1.55) at 126-153 days when compared with the reference interval (14-41 days). This corresponded to 1.09-times increased odds of influenza every 28 days (aOR = 1.09; 95% CI: 1.04-1.15). Individuals aged 18-64 years showed the greatest decline in protection against influenza A(H1N1) (aORper 28 days = 1.26; 95% CI: 0.97-1.64), whereas for individuals aged ≥ 65 years, it was against influenza A(H3N2) (aORper 28 days = 1.20; 95% CI: 1.08-1.33). We did not observe evidence of waning vaccine protection for individuals aged < 18 years.ConclusionsInfluenza vaccine protection wanes during an influenza season. Understanding the optimal timing of vaccination could ensure robust protection during seasonal influenza activity.

Plasmid genomic epidemiology of carbapenem-hydrolysing class D ß-lactamase (CDHL)-producing Enterobacterales in Canada, 2010-2021.

Carbapenems are last-resort antibiotics for treatment of infections caused by multidrug-resistant Enterobacterales, but carbapenem resistance is a rising global threat due to the acquisition of carbapenemase genes. Oxacillinase-48 (bla OXA-48)-type carbapenemases are increasing in abundance in Canada and elsewhere; these genes are frequently found on mobile genetic elements and are associated with specific transposons. This means that alongside clonal dissemination, bla OXA-48-type genes can spread through plasmid-mediated horizontal gene transfer. We applied whole genome sequencing to characterize 249 bla OXA-48-type-producing Enterobacterales isolates collected by the Canadian Nosocomial Infection Surveillance Program from 2010 to 2021. Using a combination of short- and long-read sequencing, we obtained 70 complete and circular bla OXA-48-type-encoding plasmids. Using MOB-suite, four major plasmids clustered were identified, and we further estimated a plasmid cluster for 91.9 % (147/160) of incomplete bla OXA-48-type-encoding contigs. We identified different patterns of carbapenemase mobilization across Canada, including horizontal transmission of bla OXA-181/IncX3 plasmids (75/249, 30.1 %) and bla OXA-48/IncL/M plasmids (47/249, 18.9 %), and both horizontal transmission and clonal transmission of bla OXA-232 for Klebsiella pneumoniae ST231 on ColE2-type/ColKP3 plasmids (25/249, 10.0 %). Our findings highlight the diversity of OXA-48-type plasmids and indicate that multiple plasmid clusters and clonal transmission have contributed to bla OXA-48-type spread and persistence in Canada.

Verification, Analytical Sensitivity, Cost-effectiveness, and Comparison of 4 Candida auris Screening Methods.

In this verification study, we compare and contrast the performance characteristics of chromogenic agar culture, direct polymerase chain reaction (PCR), and broth enrichment followed by culture or PCR for the detection of Candida auris colonization. We find that culture and PCR both offer excellent performance, with broth enrichment offering little performance advantage given its cost.

Evaluation of the utility and cost of secondary confirmatory testing for Neisseria gonorrhoeae identification from culture.

Current guideline recommends the use of two identification methods for Neisseria gonorrhoeae. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) is now used for primary identification and may be sufficient for definitive identification of N. gonorrhoeae. The performance of three secondary tests (BactiCard, RapID NH and NET test) were compared using 45 bacterial isolates, including 37 Neisseria species. These secondary tests demonstrated diminished specificity (67% - 88%) for N. gonorrhoeae compared with MALDI-TOF. Additionally, data from six clinical microbiology laboratories was used to compare confirmatory test costs and the agreement of results with MALDI-TOF. Discrepancies were documented for 9.4% of isolates, though all isolates (n= 288) identified by MALDI-TOF as N. gonorrhoeae were confirmed by the reference laboratory. These data demonstrate that MALDI-TOF alone is sufficient for N. gonorrhoeae identification, as secondary did not add diagnostic value but do add costs to the testing process.

Nirmatrelvir-ritonavir use among adults hospitalized with COVID-19 during the Omicron phase of the COVID-19 pandemic, Canadian Nosocomial Infection Surveillance Program.

Background: Recent studies have demonstrated the effectiveness of nirmatrelvir-ritonavir in reducing the risk of progression to severe disease among outpatients with mild to moderate coronavirus disease 2019 (COVID-19); however, data are limited regarding the use and role of nirmatrelvir-ritonavir among hospitalized patients. This study describes the use and outcomes of nirmatrelvir-ritonavir among adults hospitalized with COVID-19 in a sentinel network of Canadian acute care hospitals during the Omicron variant phase of the pandemic. Methods: The Canadian Nosocomial Infection Surveillance Program conducts surveillance of hospitalized patients with COVID-19 in acute care hospitals across Canada. Demographic, clinical, treatment and 30-day outcome data were collected by chart review by trained infection control professionals using standardized questionnaires. Results: From January 1 to December 31, 2022, 13% (n=490/3,731) of adult patients (18 years of age and older) hospitalized with COVID-19 in 40 acute care hospitals received nirmatrelvir-ritonavir either at admission or during hospitalization. Most inpatients who received nirmatrelvir-ritonavir, 79% of whom were fully vaccinated, had at least one pre-existing comorbidity (97%) and were of advanced age (median=79 years). Few were admitted to an intensive care unit (2.3%) and among the 490 nirmatrelvir-ritonavir treated inpatients, there were 13 (2.7%) deaths attributable to COVID-19. Conclusion: These findings from a large sentinel network of Canadian acute-care hospitals suggest that nirmatrelvir-ritonavir is being used to treat adult COVID-19 patients at admission who are at risk of progression to severe disease or those who acquired COVID-19 in hospital. Additional research on the efficacy and indications for nirmatrelvir-ritonavir use in hospitalized patients is warranted to inform future policies and guidelines.