Clinical application of phage immunoprecipitation sequencing to diagnose enterovirus D68 as the underlying etiology in a case of Gullain-Barré syndrome.

Gullain-Barré syndrome (GBS) is an acute peripheral neuropathy often preceded by respiratory or gastrointestinal infections, though molecular testing of cerebrospinal fluid (CSF) is often inconclusive. In a recent case of severe pediatric GBS in British Columbia, Canada, we detected CSF antibodies against enterovirus D (EV-D) to link GBS with prior EV-D68 respiratory infection.

Plasmid genomic epidemiology of blaKPC carbapenemase-producing Enterobacterales in Canada, 2010-2021.

Carbapenems are considered last-resort antibiotics for the treatment of infections caused by multidrug-resistant Enterobacterales, but carbapenem resistance due to acquisition of carbapenemase genes is a growing threat that has been reported worldwide. Klebsiella pneumoniae carbapenemase (blaKPC) is the most common type of carbapenemase in Canada and elsewhere; it can hydrolyze penicillins, cephalosporins, aztreonam, and carbapenems and is frequently found on mobile plasmids in the Tn4401 transposon. This means that alongside clonal expansion, blaKPC can disseminate through plasmid- and transposon-mediated horizontal gene transfer. We applied whole genome sequencing to characterize the molecular epidemiology of 829 blaKPC carbapenemase-producing isolates collected by the Canadian Nosocomial Infection Surveillance Program from 2010 to 2021. Using a combination of short-read and long-read sequencing, we obtained 202 complete and circular blaKPC-encoding plasmids. Using MOB-suite, 10 major plasmid clusters were identified from this data set which represented 87% (175/202) of the Canadian blaKPC-encoding plasmids. We further estimated the genomic location of incomplete blaKPC-encoding contigs and predicted a plasmid cluster for 95% (603/635) of these. We identified different patterns of carbapenemase mobilization across Canada related to different plasmid clusters, including clonal transmission of IncF-type plasmids (108/829, 13%) in K. pneumoniae clonal complex 258 and novel repE(pEh60-7) plasmids (44/829, 5%) in Enterobacter hormaechei ST316, and horizontal transmission of IncL/M (142/829, 17%) and IncN-type plasmids (149/829, 18%) across multiple genera. Our findings highlight the diversity of blaKPC genomic loci and indicate that multiple, distinct plasmid clusters have contributed to blaKPC spread and persistence in Canada.

Blood culture collection practices in NICU; A national survey.

Background: Sepsis is the leading cause of mortality and morbidity in neonates. Blood cultures are the gold standard in diagnosing neonatal sepsis; however, there are currently no consensus guidelines for blood culture collection in neonates and significant practice variation exists in Neonatal Intensive Care Units (NICUs) globally. Objective: To examine current practices in obtaining blood cultures in the evaluation of neonatal sepsis in NICUs across Canada. Methods: A nine-item electronic survey was sent to each of the 29 level-3 NICUs in Canada, which are equipped to provide highly specialized care for newborns. Results: Responses were received from 90% (26/29) of sites. Sixty-five percent (17/26) of sites have blood culture collection guidelines for the investigation of neonatal sepsis. Forty-eight percent (12/25) of sites routinely target 1.0 mL per culture bottle. In late-onset sepsis (LOS), 58% (15/26) of sites process one aerobic culture bottle, whereas four sites routinely add anaerobic culture bottles. In early-onset sepsis (EOS) in very low birth weight infants (BW <1.5 kg), 73% (19/26) of sites use umbilical cord blood, and 72% (18/25) use peripheral venipuncture. Two sites routinely collect cord blood for culture in EOS. Only one site applies the concept of differential time-to-positivity to diagnose central-line-associated bloodstream infection. Conclusions: There is significant practice variation in methods used to obtain blood cultures in level-3 NICUs across Canada. Standardization of blood culture collection practices can provide reliable estimates of the true incidence of neonatal sepsis and help to develop appropriate antimicrobial stewardship strategies.

Characterization of Healthcare-Associated and Community-Associated Clostridioides difficile Infections among Adults, Canada, 2015-2019.

We investigated epidemiologic and molecular characteristics of healthcare-associated (HA) and community-associated (CA) Clostridioides difficile infection (CDI) among adult patients in Canadian Nosocomial Infection Surveillance Program hospitals during 2015-2019. The study encompassed 18,455 CDI cases, 13,735 (74.4%) HA and 4,720 (25.6%) CA. During 2015-2019, HA CDI rates decreased by 23.8%, whereas CA decreased by 18.8%. HA CDI was significantly associated with increased 30-day all-cause mortality as compared with CA CDI (p<0.01). Of 2,506 isolates analyzed, the most common ribotypes (RTs) were RT027, RT106, RT014, and RT020. RT027 was more often associated with CDI-attributable death than was non-RT027, regardless of acquisition type. Overall resistance C. difficile rates were similar for all drugs tested except moxifloxacin. Adult HA and CA CDI rates have declined, coinciding with changes in prevalence of RT027 and RT106. Infection prevention and control and continued national surveillance are integral to clarifying CDI epidemiology, investigation, and control.

A Prospective Observational Cohort Comparison of SARS-CoV-2 Seroprevalence Between Paramedics and Matched Blood Donors in Canada During the COVID-19 Pandemic.

STUDY OBJECTIVE: SARS-CoV-2 represents an occupational risk to paramedics, who work in uncontrolled environments. We sought to identify the occupation-specific risk to paramedics by comparing their seroprevalence of SARS-CoV-2 infection-specific antibodies to that of blood donors in Canada. METHODS: In this prospective cohort study, we performed serology testing (Elecsys Anti-SARS-CoV-2 nucleocapsid assay) on samples from paramedics and blood donors (January to July 2021) in Canada. Paramedic samples were compared to blood donor samples through 1:1-matched (based on age, sex, location, date of blood collection, and vaccination status) and raking weighted comparisons. We compared the seroprevalence with a risk difference (and 95% confidence interval [CI]) and performed secondary analyses within subgroups defined by vaccination status. RESULTS: The 1:1 match included 1,627 cases per group; in both groups, 723 (44%) were women, with a median age of 38. The raking weighted comparison included 1,713 paramedic samples and 19,515 blood donor samples, with similar characteristics. In the 1:1 match, the seroprevalence was similar (difference 1.2; 95% CI -0.20 to 2.7) between paramedics (5.2%) and blood donors (3.9%). The raking weighted comparison was consistent (difference 0.97; 95% CI -0.10 to 2.0). The unvaccinated paramedic samples, in comparison to the blood donor samples, demonstrated a higher seroprevalence in the 1:1 (difference 5.9; 95% CI 1.8 to 10) and weighted (difference 6.5; 95% CI 1.8 to 10) comparisons. Among vaccinated cases, the between-group seroprevalence was similar. CONCLUSION: Overall, paramedics demonstrated similar evidence of prior SARS-CoV-2 infection to that of blood donors. However, among unvaccinated individuals, evidence of prior infection was higher among paramedics compared to blood donors.

Self-Collected Saline Gargle Samples as an Alternative to Health Care Worker-Collected Nasopharyngeal Swabs for COVID-19 Diagnosis in Outpatients.

We assessed the performance, stability, and user acceptability of swab-independent self-collected saliva and saline mouth rinse/gargle sample types for the molecular detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in adults and school-aged children. Outpatients who had recently been diagnosed with COVID-19 or were presenting with suspected COVID-19 were asked to have a nasopharyngeal (NP) swab collected and provide at least one self-collected sample type. Participants were also asked about sample acceptability using a five-point Likert scale. For those previously diagnosed with COVID-19, all samples underwent real-time PCR testing using a lab-developed assay, and the majority were also tested using an FDA-authorized assay. For those presenting with suspected COVID-19, only those with a positive nasopharyngeal swab sample went on to have other samples tested. Saline mouth rinse/gargle and saliva samples were tested daily at time zero, day 1, and day 2 to assess nucleic acid stability at room temperature. Fifty participants (aged 4 to 71 years) were included; of these, 40 had at least one positive sample and were included in the primary sample yield analysis. Saline mouth rinse/gargle samples had a sensitivity of 98% (39/40), while saliva samples had a sensitivity of 79% (26/33). Both saline mouth rinse/gargle and saliva samples showed stable viral RNA detection after 2 days of room temperature storage. Mouth rinse/gargle samples had the highest (mean, 4.9) and health care worker (HCW)-collected NP swabs had the lowest acceptability scores (mean, 3.1). In conclusion, saline mouth rinse/gargle samples demonstrated higher combined user acceptability ratings and analytical performance than saliva and HCW-collected NP swabs. This sample type is a promising swab-independent option, particularly for outpatient self-collection in adults and school-aged children.

Development and validation of a new triplex real-time quantitative reverse Transcriptase-PCR assay for the clinical detection of SARS-CoV-2.

To increase the repertoire of PCR based laboratory developed tests (LDTs) for the detection of SARS-CoV-2, we describe a new multiplex assay (SORP), targeting the SARS-CoV-2's, Spike and ORF8 genes. The widely used human RNaseP internal control was modified to specifically co-amplify the RNaseP mRNA. The SORP triplex assay was tested on a cohort (n = 372; POS = 144/NEG = 228) of nasopharyngeal flocked swab (NPFS) specimens, previously tested for the presence of SARS-CoV-2 using a PCR assay targeting E and RdRp genes. The overall sensitivity and specificity of the SORP assay was: 99.31% (95% CI: 96.22-99.98%), 100.0% (95% CI: 98.4-100%) respectively. The SORP assay could also detect a panel of variants of concern (VOC) from the B1.1.7 (UK) and B1.351 (SA) lineage. In summary, access to a repertoire of new SARS-CoV-2 LDT's would assist diagnostic laboratories in developing strategies to overcome some of the testing issues encountered during high-throughput SARS-CoV-2 testing.

Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies.

Influenza vaccination programmes are assumed to have a herd effect and protect contacts of vaccinated persons from influenza virus infection. We searched MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Global Health and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to March 2014 for studies assessing the protective effect of influenza vaccination vs no vaccination on influenza virus infections in contacts. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Of 43,082 screened articles, nine randomised controlled trials (RCTs) and four observational studies were eligible. Among the RCTs, no statistically significant herd effect on the occurrence of influenza in contacts could be found (OR: 0.62; 95% CI: 0.34-1.12). The one RCT conducted in a community setting, however, showed a significant effect (OR: 0.39; 95% CI: 0.26-0.57), as did the observational studies (OR: 0.57; 95% CI: 0.43-0.77). We found only a few studies that quantified the herd effect of vaccination, all studies except one were conducted in children, and the overall evidence was graded as low. The evidence is too limited to conclude in what setting(s) a herd effect may or may not be achieved.

Barriers to healthcare-worker adherence to infection prevention and control practices in British Columbia during the coronavirus disease 2019 (COVID-19) pandemic: A cross-sectional study.

OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic highlighted the importance of robust infection prevention and control (IPAC) practices to maintain patient and staff safety. However, healthcare workers (HCWs) face many barriers that affect their ability to follow these practices. We identified barriers affecting HCW adherence to IPAC practices during the pandemic in British Columbia, Canada. DESIGN: Cross-sectional web-based survey. SETTING: Acute care, long-term care or assisted living, outpatient, mental health, prehospital care, and home care. PARTICIPANTS: Eligible respondents included direct-care providers and IPAC professionals working in these settings in all health authorities across British Columbia. METHODS: We conducted a web-based survey from August to September 2021 to assess respondent knowledge and attitudes toward IPAC within the context of the COVID-19 pandemic. Respondents were asked to rate the extent to which various barriers affected their ability to follow IPAC practices throughout the pandemic and to make suggestions for improvement. RESULTS: The final analysis included 2,488 responses; 36% of respondents worked in acute care. Overall, perceptions of IPAC practice among non-IPAC professionals were positive. The main self-perceived barriers to adherence included inadequate staffing to cover absences (58%), limited space in staff rooms (57%), multibed rooms (51%), and confusing messages about IPAC practices (51%). Common suggestions for improvement included receiving more support from IPAC leadership and clearer communication about required IPAC practices. CONCLUSIONS: Our findings highlight frontline HCW perspectives regarding priority areas of improvement for IPAC practices. They will inform policy and guideline development to prevent transmission of COVID-19 and future emerging infections.

Trends in SARS-CoV-2-related pediatric hospitalizations reported to the Canadian Nosocomial Infection Surveillance Program, March 2020 to December 2022.

Objective: This study describes trends in COVID-19 hospitalizations and healthcare-associated (HA) COVID-19 in Canada among pediatric (age <18 years) patients during pre-Omicron and Omicron-dominant periods. Design: Prospective surveillance for COVID-19 infection. Setting: The Canadian Nosocomial Infection Surveillance Program is a sentinel surveillance system with 45 hospitals providing COVID-19 data on pediatric patients, including all 13 pediatric tertiary care facilities in Canada. Patients: Pediatric patients hospitalized with laboratory-confirmed COVID-19 at a participating hospital between March 1, 2020, and December 31, 2022. Methods: Analyzed case-level data on pediatric patients with COVID-19, including demographics, acquisition source, and outcomes. Results: Among 5,143 pediatric cases, the majority (81%) were reported during the Omicron-dominant period (beginning December 26, 2021). However, a lower proportion required intensive care during the Omicron wave (11% vs 14%, P < 0.05); no difference in mortality was observed. Of those patients admitted to hospital due to COVID-19 (n = 2,700), 45% had at least one pre-existing comorbidity. The majority (90%) of patients with HA-COVID-19 were reported during the Omicron period. There was no difference in mortality between patients with HA and community-associated (CA) infection, although a greater proportion of CA infections led to intensive care unit admission (6% vs 13%, P < 0.01). Conclusions: Surveillance findings indicate that both HA- and CA-COVID-19 hospitalizations in Canada increased among pediatric patients following the emergence of the Omicron variant, although disease severity decreased. Pre-existing health conditions were common among pediatric patients hospitalized with COVID-19, highlighting the importance of preventing severe illness in this sub-population.

Association of cerebrospinal fluid parameters with treatment and complications among children with cerebrospinal fluid shunt infections: a multicenter study.

OBJECTIVE: Cerebrospinal fluid (CSF) white blood cell (WBC) count, neutrophil percentage, protein concentration, and glucose level are typically measured at diagnosis and serially during the treatment of CSF shunt infections. The objective of this retrospective cohort study was to describe the longitudinal profile of CSF parameters in children with CSF shunt infections and assess their association with treatment and outcome. METHODS: Participants were children treated at 11 tertiary pediatric hospitals in Canada and the United States for CSF shunt infection, from July 1, 2013, through June 30, 2019, with hardware removal, external ventricular drain placement, intravenous antibiotics, and subsequent permanent shunt reinsertion. The relationship between CSF parameters and a complicated course (a composite outcome representing children with at least one of the following: contiguous soft-tissue infection, worsening hydrocephalus, CSF leak, intracranial bleed, brain abscess, venous thrombosis, reinfection after insertion of the new shunt, other complication, ICU admission, or death) was analyzed. RESULTS: A total of 109 children (median age 2.8 years, 44% female) were included in this study. CSF pleocytosis, elevated protein, and hypoglycorrhachia had sensitivities of 69%, 47%, and 38% for the diagnosis of culture-confirmed CSF shunt infection, respectively. The longitudinal profile of the neutrophil percentage followed a monotonic trend, decreasing by 1.5% (95% CI 1.0%-2.0%, p < 0.0001) per day over the course of treatment. The initial WBC count differed significantly between pathogens (p = 0.011), but the proportion of neutrophils, protein concentration, and glucose level did not, and was lowest with Cutibacterium acnes. The duration of antibiotic treatment and the time to shunt reinsertion were longer in patients with a higher initial neutrophil percentage. Fifty-eight patients (53%) had one or more complications during their admission. A neutrophil percentage > 44% (Youden index) in the initial CSF sample was associated with a 1.8-fold (95% CI 1.2- to 2.8-fold) higher relative risk of a complicated course. In a random-intercept, random-slope linear mixed-effects model, the longitudinal neutrophil trajectory differed significantly between patients with and without complications (p = 0.030). CONCLUSIONS: A higher proportion of neutrophils in the CSF at diagnosis was associated with a complicated clinical course. Other CSF parameters were associated with treatment and outcome; however, wide variability in values may limit their clinical utility.

Bordetella holmesii, an emerging cause of septic arthritis.

Bordetella holmesii is a well-described pathogen in asplenic and immunocompromised patients. Here we report the first two published cases of septic arthritis caused by B. holmesii documented in apparently immunocompetent patients and unaccompanied by bacteremia.

Novel hand hygiene promotion method in a pediatric and maternity hospital: A quality improvement pilot project using auditory feedback.

A pilot quality improvement project was conducted to examine the effect of playing an applause sound effect at a busy hospital concourse for three consecutive days whenever hand hygiene behavior was observed. The immediate effect was documented. The project demonstrated observable interest among people passing by, and hand hygiene events triggered by the sound effect represented 10.1% of all hand hygiene events documented. This supports the possible utility of this intervention in generating public awareness and increasing hand hygiene behavior and demonstrates the feasibility of a longer trial utilizing audio devices.

Vaccination, time lost from work, and COVID-19 infections: a Canadian healthcare worker retrospective cohort study.

The COVID-19 pandemic highlighted hurdles for healthcare delivery and personnel globally. Vaccination has been an important tool for preventing severe illness and death in healthcare workers (HCWs) as well as the public at large. However, vaccination has resulted in some HCWs requiring time off work post-vaccination to recover from adverse events. We aimed to understand which HCWs needed to take time off work post-vaccination, for which vaccine types and sequence, and how post-vaccination absence impacted uptake of booster doses in a cohort of 26,267 Canadian HCWs. By March 31, 2022, more than 98% had received at least two doses of the approved COVID-19 vaccines, following a two-dose mandate. We found that recent vaccination and longer intervals between doses were associated with significantly higher odds of time-loss, whereas being a medical resident and receiving the BNT162b2 vaccine were associated with lower odds. A history of lab-confirmed SARS-CoV-2 infection was associated with lower odds of receiving a booster dose compared with no documented infection, aOR 0.61 (95% CI: 0.55, 0.68). Similarly, taking sick time following the first or second dose was associated with lower odds of receiving a booster dose, aOR 0.83 (95% CI: 0.75, 0.90). As SARS-CoV-2 becomes endemic, the number and timing of additional doses for HCWs requires consideration of prevention of illness as well as service disruption from post-vaccination time-loss. Care should be taken to ensure adequate staffing if many HCWs are being vaccinated, especially for coverage for those who are more likely to need time off to recover.

Effectiveness of a neonatal intensive care unit-specific antimicrobial stewardship program: A ten-year review.

OBJECTIVE: To evaluate the change in consumption of specific antibiotics in a neonatal intensive care unit after the implementation of an antimicrobial stewardship program (ASP). DESIGN: Retrospective cohort study between January 1, 2010, and December 31,2019. SETTING: The neonatal intensive care unit at British Columbia Women's Hospital (Vancouver Canada), a tertiary-care center. PATIENTS: Admitted neonates prescribed antibiotics. METHODS: We implemented an ASP with an early implementation phase starting in January 2014 (period 2) and a later phase starting in January 2017 (period 3). Patient demographics were collected, including birth weight, gestational age, history of necrotizing enterocolitis (NEC), and surgical operations from existing databases. Interrupted time-series analysis was used, and comparison of antibiotic days of therapy (DOT) averages were conducted across the preimplementation period (period 1), period 2, and period 3 regarding total patients and subgroups. RESULTS: We identified 4,512 infants. There was a significant decrease in DOT from 472 (95% confidence interval [CI], 431-517) in period 1 to 405 (95% CI, 367-446) in period 2 to 313 (95% CI, 280-350) in period 3. We detected a significant decrease in the use of ampicillin, aminoglycosides, cloxacillin, and linezolid but not in vancomycin or cefotaxime. Subgroup analyses of infants <1,500 g and those without NEC or surgery showed decreases in the use of cloxacillin, aminoglycosides, and linezolid. CONCLUSIONS: The implementation of an ASP was associated with a significant decrease in the overall DOT and use of certain antibiotics. This study presents important targets for ongoing ASP work.

Barriers to infection prevention and control in long-term care/assisted living settings in British Columbia during the COVID-19 pandemic: a cross-sectional survey.

BACKGROUND: The COVID-19 pandemic disproportionately impacted long-term care and assisted living (LTC/AL) facilities in Canada, where infection prevention and control (IPAC) programs had been suboptimal. We aimed to identify barriers affecting healthcare workers' (HCW) adherence to IPAC practices during the pandemic in British Columbia in LTC/AL compared to acute care settings. METHODS: We conducted a web-based survey of direct care providers and IPAC professionals across BC from August to September 2021, focused on knowledge and attitudes toward IPAC within the context of the COVID-19 pandemic, and barriers that affected respondents' abilities to follow IPAC practices throughout the pandemic. RESULTS: The final analysis included 896 acute care respondents and 441 from LTC/AL. More LTC/AL respondents reported experiencing the following barriers: following IPAC guidance was of lower priority compared to other tasks (29.1% vs. 14.7%, FDR = 0.001) and not their responsibility (28.0% vs. 11.2%, FDR = 0.001); limited supplies for personal protective equipment (PPE) (49.0% vs. 33.6%, FDR = 0.001), hand hygiene products (42.2% vs. 28.8%, FDR = 0.001), and cleaning/disinfection products (44.1% vs. 30.3%, FDR = 0.001); deficits in IPAC leadership support (46.2% vs. 38.9%, FDR = 0.012), IPAC education and training (46.9% vs. 32.0%, FDR = 0.001), and patient care knowledge for managing COVID-19 infections (46.6% vs. 36.0%, FDR = 0.001). CONCLUSIONS: This survey found that barriers to HCWs' adherence to IPAC practices during the COVID-19 pandemic were different in LTC/AL settings compared to acute care. Improvement efforts should focus on strengthening IPAC programs in LTC/AL, particularly enhanced IPAC staffing/leadership, increased training and education, and improving access to PPE, hand hygiene, and cleaning products.

Epidemiology of Primary and Recurrent Healthcare-Associated and Community-Associated Pediatric Clostridioides difficile Infection in Canada, 2015-2020.

Clostridioides difficile infection (CDI) among children remains a concerning cause of morbidity in hospital settings. We present epidemiological and molecular trends in healthcare- and community-associated CDI among children in Canadian inpatient and outpatient settings, including those who experienced recurrent infections.

Extraction-free clinical detection of SARS-CoV-2 virus from saline gargle samples using Hamilton STARlet liquid handler.

As part of the COVID-19 pandemic, clinical laboratories have been faced with massive increases in testing, resulting in sample collection systems, reagent, and staff shortages. We utilized self-collected saline gargle samples to optimize high throughput SARS-CoV-2 multiplex polymerase chain reaction (PCR) testing in order to minimize cost and technologist time. This was achieved through elimination of nucleic acid extraction and automation of sample handling on a widely available robotic liquid handler, Hamilton STARlet. A customized barcode scanning script for reading the sample ID by the Hamilton STARlet's software system was developed to allow primary tube sampling. Use of pre-frozen SARS-CoV-2 assay reaction mixtures reduced assay setup time. In both validation and live testing, the assay produced no false positive or false negative results. Of the 1060 samples tested during validation, 3.6% (39/1060) of samples required retesting as they were either single gene positive, had internal control failure or liquid aspiration error. Although the overall turnaround time was only slightly faster in the automated workflow (185 min vs 200 min), there was a 76% reduction in hands-on time, potentially reducing staff fatigue and burnout. This described process from sample self-collection to automated direct PCR testing significantly reduces the total burden on healthcare systems in terms of human resources and reagent requirements.

Respiratory syncytial virus epidemiology and clinical severity before and during the COVID-19 pandemic in British Columbia, Canada: a retrospective observational study.

Background: The COVID-19 pandemic has perturbed the seasonality of respiratory syncytial virus (RSV) infections. However, we lack data on how this impacted the severity of paediatric RSV cases. The objective of this study was to describe the clinical severity of RSV cases before, during and after pandemic measures in British Columbia (BC), Canada. Methods: Retrospective study of RSV cases from September 1st, 2017 to May 15th, 2023, with a review of RSV outcomes in children below 18 years old at BC's paediatric hospital. Temporal changes in RSV cases and hospitalisations were quantified using interrupted time series. Findings: BC experienced only 11 RSV cases (from 95,266 tests) between September 2020 and August 2021. This was followed by a resurgence of 9,529 RSV cases (219,566 tests [4.3% positive tests]) in 2021-22 and 8,215 cases (124,449 tests [6.6% positive tests]) in 2022-23, increased compared to 1,750 cases (48,664 tests [3.6% positive tests]) per corresponding yearly period in 2017-20. From September 2017 to May 2023, the median age of children with RSV at BC Children's Hospital increased from 8.7 [IQR: 2.0-26.0] to 19.6 [3.9-43.7] months per yearly period. More children were hospitalised in 2022-23 (n = 360), compared to 2017-20 (n = 168 per period) and 2021-22 (n = 172). However, we detected no increase in hospitalisations or ICU admissions in children born prematurely or with chronic cardiorespiratory conditions. Interpretation: The increased detection of symptomatic RSV cases in older children in 2021-22 and increased RSV-related hospitalisations in 2022-23 suggest a gradual increase in the pool of immunologically vulnerable children due to a prolonged lack of viral exposure. Funding: Government of Canada via its COVID-19 Immunity Task Force.