Did the health care vaccine mandate work? An evaluation of the impact of the COVID-19 vaccine mandate on vaccine uptake and infection risk in a large cohort of Canadian health care workers.

BACKGROUND: We aimed to evaluate the impact of health care vaccine mandates on vaccine uptake and infection risk in a cohort of Canadian health care workers (HCWs). METHODS: We conduct interrupted time series analysis through a regression discontinuity in time approach to estimate the immediate and delayed impact of the mandate. Multilevel mixed effect modeling fitted with restricted maximum likelihood was used to estimate impact on infection risk. RESULTS: The immediate and sustained effects of the mandate was a 0.19% (P < .05) and a 0.012% (P < .05) increase in the daily proportion of unvaccinated HCWs getting their first dose, respectively. An additional 623 (95% confidence interval: 613-667) HCWs received first doses compared to the predicted uptake absent the mandate. Adjusted test positivity declined by 0.053% (95% confidence interval: 0.035%, 0.069) for every additional day the mandate was in effect. DISCUSSION: Our results indicate that the mandate was associated with significant increases in vaccine uptake and infection risk reduction in the cohort. CONCLUSIONS: Given the benefit that vaccination could bring to HCWs, understanding strategies to enhance uptake is crucial for bolstering health system resilience, but steps must be taken to avert approaches that sacrifice trust, foster animosity, or exacerbate staffing constraints for short-term results.

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.

Urban-rural divide in COVID-19 infection and vaccination rates in healthcare workers in British Columbia, Canada.

Introduction: Healthcare workers (HCWs) play a critical role in responding to the COVID-19 pandemic. Early in the pandemic, urban centres were hit hardest globally; rural areas gradually became more impacted. We compared COVID-19 infection and vaccine uptake in HCWs living in urban versus rural locations within, and between, two health regions in British Columbia (BC), Canada. We also analysed the impact of a vaccine mandate for HCWs. Methods: We tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates and vaccine uptake in all 29,021 HCWs in Interior Health (IH) and all 24,634 HCWs in Vancouver Coastal Health (VCH), by occupation, age and home location, comparing to the general population in that region. We then evaluated the impact of infection rates as well as the mandate on vaccination uptake. Results: While we found an association between vaccine uptake by HCWs and HCW COVID-19 rates in the preceding 2-week period, the higher rates of COVID-19 infection in some occupational groups did not lead to increased vaccination in these groups. By 27 October 2021, the date that unvaccinated HCWs were prohibited from providing healthcare, only 1.6% in VCH compared with 6.5% in IH remained unvaccinated. Rural workers in both areas had significantly higher unvaccinated rates compared with urban dwellers. Over 1800 workers, comprising 6.7% of rural HCWs and 3.6% of urban HCWs, remained unvaccinated and set to be terminated from their employment. While the mandate prompted a significant increase in uptake of second doses, the impact on the unvaccinated was less clear. Conclusions: As rural areas often suffer from under-staffing, loss of HCWs could have serious impacts on healthcare provision as well as on the livelihoods of unvaccinated HCWs. Greater efforts are needed to understand how to better address the drivers of rural-related vaccine hesitancy.

Résumé Introduction: Les travailleurs de la santé (TS) jouent un rôle essentiel dans la réponse à la pandémie de COVID-19. Au début de la pandémie, les centres urbains ont été les plus durement touchés à l'échelle mondiale; les zones rurales ont progressivement été plus touchées. Nous avons comparé l'infection à la COVID-19 et l'adoption du vaccin chez les travailleuses et travailleurs de la santé vivant dans des zones urbaines et rurales au sein de deux régions sanitaires de la Colombie-Britannique (C.-B.), au Canada, et entre ces régions. Nous avons également analysé l'impact d'un mandat de vaccination pour les travailleuses et travailleurs de la santé. Méthodes: Nous avons suivi les infections au SRAS-CoV-2 confirmées en laboratoire, les taux de positivité et l'adoption du vaccin chez les 29 021 TS d'Interior Health (IH) et les 24 634 TS de Vancouver Coastal Health (VCH), par profession, âge et lieu de résidence, en les comparant à la population générale de cette région. Nous avons ensuite évalué l'impact des taux d'infection ainsi que du mandat sur le recours à la vaccination. Résultats: Bien que nous ayons trouvé une association entre l'adoption du vaccin par les TS et les taux de COVID-19 des travailleurs de la santé au cours de la période de deux semaines précédentes, les taux plus élevés d'infection par la COVID-19 dans certains groupes professionnels n'ont pas entraîné une augmentation de la vaccination dans ces groupes. En date du 27 octobre 2021, date à laquelle il était interdit aux travailleuses et travailleurs de santé non vaccinés de fournir des soins de santé, seul 1,6% des travailleuses et travailleurs de la VCH, contre 6,5% des travailleuses et travailleurs de l'IH, n'étaient toujours pas vaccinés. Les travailleuses et travailleurs ruraux des deux zones présentaient des taux de non-vaccination significativement plus élevés que les citadins. Plus de 1 800 travailleuses et travailleurs, soit 6,7% des TS ruraux et 3,6% des TS urbains, n'étaient toujours pas vaccinés et devaient être licenciés. Bien que le mandat ait entraîné une augmentation significative de la prise des deuxièmes doses, l'impact sur les personnes non-vaccinées était moins clair. Conclusions: Comme les zones rurales souffrent souvent d'un manque de personnel, la perte de TS pourrait avoir de graves répercussions sur la prestation des soins de santé ainsi que sur les moyens de subsistance des TS non-vaccinés. Des efforts plus importants sont nécessaires pour comprendre comment mieux aborder les facteurs d'hésitation à SE faire vacciner en milieu rural. Mots-clés: Travailleuses et travailleurs de la santé, COVID-19, vaccination, mandat de vaccination, milieu rural.

A multi-site, international laboratory study to assess the performance of penicillin susceptibility testing of Staphylococcus aureus.

OBJECTIVES: There is clinical uncertainty over the optimal treatment for penicillin-susceptible Staphylococcus aureus (PSSA) infections. Furthermore, there is concern that phenotypic penicillin susceptibility testing methods are not reliably able to detect some blaZ-positive S. aureus. METHODS: Nine S. aureus isolates, including six genetically diverse strains harbouring blaZ, were sent in triplicate to 34 participating laboratories from Australia (n = 14), New Zealand (n = 6), Canada (n = 12), Singapore (n = 1) and Israel (n = 1). We used blaZ PCR as the gold standard to assess susceptibility testing performance of CLSI (P10 disc) and EUCAST (P1 disc) methods. Very major errors (VMEs), major error (MEs) and categorical agreement were calculated. RESULTS: Twenty-two laboratories reported 593 results according to CLSI methodology (P10 disc). Nineteen laboratories reported 513 results according to the EUCAST (P1 disc) method. For CLSI laboratories, the categorical agreement and calculated VME and ME rates were 85% (508/593), 21% (84/396) and 1.5% (3/198), respectively. For EUCAST laboratories, the categorical agreement and calculated VME and ME rates were 93% (475/513), 11% (84/396) and 1% (3/198), respectively. Seven laboratories reported results for both methods, with VME rates of 24% for CLSI and 12% for EUCAST. CONCLUSIONS: The EUCAST method with a P1 disc resulted in a lower VME rate compared with the CLSI methods with a P10 disc. These results should be considered in the context that among collections of PSSA isolates, as determined by automated MIC testing, less than 10% harbour blaZ. Furthermore, the clinical relevance of phenotypically susceptible, but blaZ-positive S. aureus, remains unclear.

Masking strategy to protect healthcare workers from COVID-19: An umbrella meta-analysis.

BACKGROUND: The burden of severe disease and death due to SARS-CoV-2 (COVID-19) pandemic among healthcare workers (HCWs) worldwide has been substantial. Masking is a critical control measure to effectively protect HCWs from respiratory infectious diseases, yet for COVID-19, masking policies have varied considerably across jurisdictions. As Omicron variants began to be predominant, the value of switching from a permissive approach based on a point of care risk assessment (PCRA) to a rigid masking policy needed to be assessed. METHODS: A literature search was conducted in MEDLINE (Ovid platform), Cochrane Library, Web of Science (Ovid platform), and PubMed to June 2022. An umbrella review of meta-analyses investigating protective effects of N95 or equivalent respirators and medical masks was then conducted. Data extraction, evidence synthesis and appraisal were duplicated. RESULTS: While the results of Forest plots slightly favoured N95 or equivalent respirators over medical masks, eight of the ten meta-analyses included in the umbrella review were appraised as having very low certainty and the other two as having low certainty. CONCLUSION: The literature appraisal, in conjunction with risk assessment of the Omicron variant, side-effects and acceptability to HCWs, along with the precautionary principle, supported maintaining the current policy guided by PCRA rather than adopting a more rigid approach. Well-designed prospective multi-centre trials, with systematic attention to the diversity of healthcare settings, risk levels and equity concerns are needed to support future masking policies.

COVID-19 hospitalisations in immunocompromised individuals in the Omicron era: a population-based observational study using surveillance data in British Columbia, Canada.

Background: People with immune dysfunction are at higher risk of severe outcomes from COVID-19 infection, but relatively little epidemiologic information is available for mostly vaccinated population in the Omicron era. This population-based study compared relative risk of breakthrough COVID-19 hospitalisation among vaccinated people identified as clinically extremely vulnerable (CEV) vs non-CEV individuals before treatment became more widely available. Methods: COVID-19 cases and hospitalisations reported to the British Columbia Centre for Disease Control (BCCDC) between January 7, 2022 and March 14, 2022 were linked with data on their vaccination and CEV status. Case hospitalisation rates were estimated across CEV status, age groups and vaccination status. For vaccinated individuals, risk ratios for breakthrough hospitalisations were calculated for CEV and non-CEV populations matched on sex, age group, region, and vaccination characteristics. Findings: Among CEV individuals, a total of 5591 COVID-19 reported cases were included, among which 1153 were hospitalized. A third vaccine dose with mRNA vaccine offered additional protection against severe illness in both CEV and non-CEV individuals. However, 2- and 3-dose vaccinated CEV population still had a significantly higher relative risk of breakthrough COVID-19 hospitalisation compared with non-CEV individuals. Interpretation: Vaccinated CEV population remains a higher risk group in the context of circulating Omicron variant and may benefit from additional booster doses and pharmacotherapy. Funding: BC Centre for Disease Control and Provincial Health Services Authority.

Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: A 14-month observational study using surveillance data.

BACKGROUND: We evaluated measures to protect healthcare workers (HCWs) in Vancouver, Canada, where variants of concern (VOC) went from <1% VOC in February 2021 to >92% in mid-May. Canada has amongst the longest periods between vaccine doses worldwide, despite Vancouver having the highest P.1 variant rate outside Brazil. METHODS: With surveillance data since the pandemic began, we tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates, and vaccine uptake in all 25,558 HCWs in Vancouver Coastal Health, by occupation and subsector, and compared to the general population. Cox regression modelling adjusted for age and calendar-time calculated vaccine effectiveness (VE) against SARS-CoV-2 in fully vaccinated (≥ 7 days post-second dose), partially vaccinated infection (after 14 days) and unvaccinated HCWs; we also compared with unvaccinated community members of the same age-range. FINDINGS: Only 3.3% of our HCWs became infected, mirroring community rates, with peak positivity of 9.1%, compared to 11.8% in the community. As vaccine coverage increased, SARS-CoV-2 infections declined significantly in HCWs, despite a surge with predominantly VOC; unvaccinated HCWs had an infection rate of 1.3/10,000 person-days compared to 0.89 for HCWs post first dose, and 0.30 for fully vaccinated HCWs. VE compared to unvaccinated HCWs was 37.2% (95% CI: 16.6-52.7%) 14 days post-first dose, 79.2% (CI: 64.6-87.8%) 7 days post-second dose; one dose provided significant protection against infection until at least day 42. Compared with community infection rates, VE after one dose was 54.7% (CI: 44.8-62.9%); and 84.8% (CI: 75.2-90.7%) when fully vaccinated. INTERPRETATION: Rigorous droplet-contact precautions with N95s for aerosol-generating procedures are effective in preventing occupational infection in HCWs, with one dose of mRNA vaccination further reducing infection risk despite VOC and transmissibility concerns. Delaying second doses to allow more widespread vaccination against severe disease, with strict public health, occupational health and infection control measures, has been effective in protecting the healthcare workforce.

Safety of administering cefazolin versus other antibiotics in penicillin-allergic patients for surgical prophylaxis at a major Canadian teaching hospital.

BACKGROUND: Cefazolin surgical prophylaxis is associated with better patient outcomes; however, its use in penicillin-allergic patients is controversial. We evaluated the safety of cefazolin as surgical prophylaxis in penicillin-allergic patients, including those with anaphylaxis histories. METHODS: We conducted a pre and postintervention quality improvement evaluation of an institution-wide policy change at a tertiary-care hospital, before (October 2017-January 2018), during (February 2018-September 2018), and after (October 2018-October 2019) transition to routine cefazolin prophylaxis for penicillin-allergic patients, including those with anaphylaxis histories but excluding severe delayed reactions (eg, Stevens-Johnson syndrome). Retrospective data was collected on all surgical prophylaxis patients with penicillin-anaphylactic histories between October 2017 and September 2018. From October 2018, we prospectively reviewed adverse events with cefazolin. Primary outcome was adverse events in penicillin-allergic patients receiving cefazolin perioperatively. RESULTS: From October 2017 to October 2019, 27,467 operations were performed. Of 220 patients with penicillin-anaphylactic histories reviewed prior to the full policy change, no statistically significant differences were reported in allergic reactions (P = .70), surgical site infections (P = 1.00), or adverse events (P = .32) with cefazolin compared to other antibiotics. Postpolicy implementation, cefazolin usage increased 18.2%, while vancomycin and clindamycin decreased by 11.4% and 62.0%, respectively. No anaphylaxis was documented in penicillin-allergic patients receiving cefazolin in either the review or quality assurance follow-up after the change. Of 3 patients developing reactions to cefazolin, none had histories of penicillin allergy. Surgical site infection rates were similar between pre and postpolicy time periods (P = .842). CONCLUSION: Administration of cefazolin in penicillin-anaphylactic patients for surgical prophylaxis appears to be safe.

Antimicrobial use among adult inpatients at hospital sites within the Canadian Nosocomial Infection Surveillance Program: 2009 to 2016.

BACKGROUND: Antimicrobial resistance is a growing threat to the world's ability to prevent and treat infections. Links between quantitative antibiotic use and the emergence of bacterial resistance are well documented. This study presents benchmark antimicrobial use (AMU) rates for inpatient adult populations in acute-care hospitals across Canada. METHODS: In this retrospective surveillance study, acute-care adult hospitals participating in the Canadian Nosocomial Infection Surveillance Program (CNISP) submitted annual AMU data on all systemic antimicrobials from 2009 to 2016. Information specific to intensive care units (ICUs) and non-ICU wards were available for 2014-2016. Data were analyzed using defined daily doses (DDD) per 1000 patient days (DDD/1000pd). RESULTS: Between 2009 and 2016, 16-18 CNISP adult hospitals participated each year and provided their AMU data (22 hospitals participated in ≥1 year of surveillance; 11 in all years). From 2009 to 2016, there was a significant reduction in use (12%) (from 654 to 573 DDD/1000pd, p = 0.03). Fluoroquinolones accounted for the majority of this decrease (47% reduction in combined oral and intravenous use, from 129 to 68 DDD/1000pd, p < 0.002). The top five antimicrobials used in 2016 were cefazolin (78 DDD/1000pd), piperacillin-tazobactam (53 DDD/1000pd), ceftriaxone (49 DDD/1000pd), vancomycin (combined oral and intravenous use was 44 DDD/1000pd; 7% of vancomycin use was oral), and ciprofloxacin (combined oral and intravenous use: 42 DDD/1000pd). Among the top 10 antimicrobials used in 2016, ciprofloxacin and metronidazole use decreased significantly between 2009 and 2016 by 46% (p = 0.002) and 26% (p = 0.002) respectively. Ceftriaxone (85% increase, p = 0.0008) and oral amoxicillin-clavulanate (140% increase, p < 0.0001) use increased significantly but contributed only a small component (8.6 and 5.0%, respectively) of overall use. CONCLUSIONS: This study represents the largest collection of dispensed antimicrobial use data among inpatients in Canada to date. Between 2009 and 2016, there was a significant 12% decrease in AMU, driven primarily by a 47% decrease in fluoroquinolone use. Modest absolute increases in parenteral ceftriaxone and oral amoxicillin-clavulanate use were noted but contributed a small amount of total AMU. Ongoing national surveillance is crucial for establishing benchmarks and antimicrobial stewardship guidelines.

Potential influence of rapid diagnostics on timeliness of management decisions for patients with positive blood cultures.

Background: The Accelerate Pheno system (AXDX) provides rapid identification (ID; 90 minutes) and antimicrobial susceptibility testing (AST; approximately 7 hours) from positive blood culture (BC) bottles. We assessed the potential of AXDX results to influence more timely antibiotic interventions with a convenience sample of 158 positive BCs. Methods: BCs with a mono-microbial Gram stain likely to be on the AXDX panel were run in parallel with the standard of care (SOC). Using results from the SOC, the medical microbiologist on call (MMOC) noted interventions made at the time of BC Gram stain and when ID and AST results were available. The timing of MMOC intervention was noted and compared with fastest potential SOC time and AXDX time. Results: Of 158 specimens selected for analysis, 144 were evaluable. ID was available 11.9 hours and AST 27.7 hours faster than SOC. Correct ID was provided for 85.2% of specimens and AST for 59.0% of specimens, with 97.5% essential agreement compared with the SOC. One hundred and thirteen clinical interventions were made on 100 specimens: 54.9% were narrowing; 33.6%, escalation; 6.2%, consultation with ID; and 3.5%, further investigation. If AXDX data had been used immediately once available, interventions would have been possible 24 hours earlier for ID interventions and 39 hours earlier for AST results. Conclusions: Results from rapid diagnostic panels such as AXDX have the potential to support timely antimicrobial de-escalation and other decisions to benefit patients, especially if paired with stewardship interventions.

Historique: Le système Accelerate Pheno (AXDX) permet de procéder à une identification rapide (ID; 90 minutes) et à des tests de susceptibilité antimicrobienne (AST; environ sept heures) à partir de bouteilles d'hémoculture (BH) positives. À l'aide d'un échantillon de commodité de 158 BH positives, les auteurs ont évalué le potentiel de résultats du système AXDX pour favoriser des interventions antibiotiques plus opportunes. Méthodologie: Les auteurs ont comparé les BH présentant une coloration de Gram monomicrobienne susceptible de se trouver sur le panel AXDX avec la norme de soins (NdS). À l'aide des résultats de la NdS, le microbiologiste médical sur appel (MMSA) a consigné les interventions effectuées au moment de la coloration de Gram de la BH et lorsque les résultats de l'ID et de l'AST étaient disponibles. Le moment de l'intervention du MMSA était consigné et comparé avec la durée de la NdS au potentiel le plus rapide et la durée de l'AXDX. Résultats: Des 158 échantillons sélectionnés en vue d'être analysés, 144 étaient évaluables. L'ID était disponible 11,9 heures et l'AST, 27,7 heures plus rapidement que la NdS. L'ID exacte était fournie pour 85,2 % des échantillons et l'AST exacte, pour 59,0 % des échantillons, selon une entente essentielle de 97,5 % par rapport à la NdS. Cent treize interventions ont été effectuées sur 100 échantillons : 54,9 % visaient à réduire le spectre, 33,6 %, à accroître la médication, 6,2 %, à demander une consultation avec l'ID et 3,5 %, à obtenir des explorations plus approfondies. Si les données de l'AXDX avaient été utilisées dès l'obtention des résultats, il aurait été possible d'agir 24 heures plus rapidement pour les interventions d'ID et 39 heures plus rapidement pour les résultats de l'AST. Conclusions: Les résultats des panels diagnostiques rapides comme l'AXDX ont le potentiel de favoriser une désescalade antimicrobienne et d'autres décisions au profit des patients, surtout s'ils s'associent à des interventions de gestion.

New Delhi metallo-ß-lactamase in Klebsiella pneumoniae and Escherichia coli, Canada.

Multidrug-resistant Klebsiella pneumoniae and Escherichia coli isolates harboring New Delhi metallo-ß-lactamase (NDM-1) were isolated from a patient who had returned to Canada from India. The NDM-1 gene was found on closely related incompatibility group A/C type plasmids. The occurrence of NDM-1 in North America is a major public health concern.

Severe atovaquone-resistant Plasmodium falciparum malaria in a Canadian traveller returned from the Indian subcontinent.

BACKGROUND: We report the first case of atovaquone/proguanil treatment failure in severe Plasmodium falciparum malaria acquired by a non-immune traveller to the Indian subcontinent. Recrudescent infection was complicated by neurological involvement 14 days after directly observed therapy with atovaquone/proguanil. Sequence analysis of the plasmodial cytochrome b gene confirmed a contribution of atovaquone resistance to treatment failure. The recrudescent isolate had a single mutation at position 268 (Tyr268Cys). Video recordings illustrate dramatic but ephemeral manifestations of malaria with neurological involvement.

Successful treatment of invasive Rhizopus infection in a child with thalassemia.

The accepted standard for treatment of zygomycetes is amphotericin B and surgical debridement, however recent data suggest that combined treatment modalities may be optimal. Newer anti-fungal agents show success in vitro and in animal models. We present the case of a 10-year-old boy with invasive Rhizopus microsporus var. rhizopodoformis who was successfully treated with a combination of modalities.