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Papers by David Patrick

Research paper thumbnail of A novel method for affixing Global Positioning System (GPS) tags to urban Norway rats (Rattus norvegicus): feasibility, health impacts and potential for tracking movement

Journal of Urban Ecology, 2017

Despite the ubiquity of rats, we lack an understanding of how they move within the urban environm... more Despite the ubiquity of rats, we lack an understanding of how they move within the urban environment. Traditional tools for studying rat movement, such as capture-mark-recapture, are time-intensive and provide coarse movement estimates. Alternative methods, such as continuous tracking by radio-telemetry are difficult to employ in cities where buildings may obstruct radio signals. Global Positioning System (GPS) tags are a promising alternative for resolving fine-scale movement patterns. To test the utility of GPS tracking for urban rats, we affixed tags to 14 sexually mature Norway rats (Rattus norvegicus) in Vancouver, Canada, using veterinary adhesive and absorbable sutures. Six GPS tags had remote-download capabilities and eight stored location data downloadable upon tag recovery. We did not acquire location data from either tag type. While the data receiver successfully recognized five of six remote-download tags, these tags had not stored any locations. Further, of the three recaptured rats (21.4%), all had dislodged tags, although there were no observable adverse health effects from tag attachment. Given low recapture success, our results suggest that remote-download technologies offer greater potential for data recovery. That remote-download tags did not record locations could be due to obstruction of tag line-of-sight with a satellite either through rat ecology (e.g. burrowing), and/or removal in obstructed areas. Future technological advancements, such as surgically implantable tags that hinder removal, may improve the potential use of GPS tags to track urban rat movement. This information is essential to develop effective rat control strategies and mitigate future rat-related public health concerns.

Research paper thumbnail of 1118. Trends of Paediatric Prescribing for Common Infections in British Columbia

Open Forum Infectious Diseases, Oct 1, 2019

Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine a... more Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine antibiogram, and an EMR BPA successfully reduced BSA and increased NSA for treatment of uncomplicated UTIs.

Research paper thumbnail of 2705. Serotype Replacement Following Childhood Pneumococcal Conjugate Vaccination Programs in British Columbia, Canada

Open Forum Infectious Diseases, Oct 1, 2019

recommendations, were prospectively enrolled through 45 general pediatric practice facilities in ... more recommendations, were prospectively enrolled through 45 general pediatric practice facilities in 30 municipalities in Greece. A single oropharyngeal sample was obtained from each subject in a standardized manner (questionnaire, procedure). Based on the time interval since the fourth dose of PCV13, the children sampled were grouped for analysis in 6 groups: 26 days to 11 months; 12-23 months; 24-35 months; 36-47 months; 48-59 months, and 60-71 months. Carriage and distribution of Streptococcus pneumoniae serotypes was detected by RT-PCR. Results: A total of 1212 children aged 14-83 months were investigated. S. pneumoniae was identified in the pharyngeal swab of 617 children (50.9%); 172/617 (27.9%) children carried > 1 pneumococcal serotypes. As a consequence of co-colonization, a total number of 718 S. pneumoniae (belonging to 28 serotypes) was identified. The carriage rate of non-PCV13 serotypes escalated within 3 years after the fourth dose and plateaued during the fourth and fifth year. The carriage rate of PCV13 serotypes escalated during the 4 years after the fourth dose and declined thereafter. 22/305 children (7.2%) carried one or more PCV13 serotypes in the first year after the fourth vaccine dose, 27/201 (13.4%) in the second year, 34/207 (16.4%) in the third year, 48/224 (21.4%) in the fourth year, 40/191 (20.9%) in the fifth year and 13/84 (15.5%) in the sixth year (P < 0.0001) (Figure 1). The colonization frequency of serotypes 3 and 19A increased with the rise of the vaccination time interval (Figure 2). Changes in the frequency of other PCV13 serotypes were not significant. Serotypes 7F, 14 and 23F were not recovered. Conclusion: Our study suggests that S. pneumoniae is present in the pharynx of children 26 days to 71 months after the completion of PCV13 vaccination, and that non-PCV13 serotypes predominate throughout this period. The carriage rate of PCV13 serotypes 3 and 19A increases significantly as the time interval from the fourth dose of PCV13 increases.

Research paper thumbnail of 1117. A Retrospective Analysis of Paediatric Prescribing in British Columbia from 2013 to 2016

Open Forum Infectious Diseases, Oct 1, 2019

Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine a... more Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine antibiogram, and an EMR BPA successfully reduced BSA and increased NSA for treatment of uncomplicated UTIs.

Research paper thumbnail of Nasopharyngeal Angiotensin Converting Enzyme 2 (ACE2) Expression as a Risk-Factor for SARS-CoV-2 Transmission in Concurrent Hospital Associated Outbreaks

BackgroundWidespread human-to-human transmission of the severe acute respiratory syndrome coronav... more BackgroundWidespread human-to-human transmission of the severe acute respiratory syndrome coronavirus two (SARS-CoV-2) stems from a strong affinity for the cellular receptor angiotensin converting enzyme two (ACE2). We investigate the relationship between a patient’s nasopharyngealACE2transcription and secondary transmission within a series of concurrent hospital associated SARS-CoV-2 outbreaks in British Columbia, Canada.MethodsEpidemiological case data from the outbreak investigations was merged with public health laboratory records and viral lineage calls, from whole genome sequencing, to reconstruct the concurrent outbreaks using infection tracing transmission network analysis.ACE2transcription and RNA viral load were measured by quantitative real-time polymerase chain reaction. The transmission network was resolved to calculate the number of potential secondary cases. Bivariate and multivariable analyses using Poisson and Negative Binomial regression models was performed to est...

Research paper thumbnail of Reconsidering the “War on Rats”: What We Know From Over a Century of Research Into Municipal Rat Management

Frontiers in Ecology and Evolution, 2022

To sustainably control urban rat infestations, management efforts need to encompass large areas o... more To sustainably control urban rat infestations, management efforts need to encompass large areas of urban centers. Therefore, the objective of this review and narrative synthesis was to collate what is known about municipal-scale rat management. We explored the management frameworks that have been used at a large scale in cities and we describe the expectations of experts who have designed and implemented these frameworks. We found that there has been a persistent “war on rats” paradigm driving this literature since the early 1900s. Not only was there little quantitative evidence to support this paradigm and associated methodologies, but together, they failed to meet the expectations of those who designed and implemented them due to real-world constraints (i.e., limited resources). To improve the field of municipal management, we identify two distinct options. First, stakeholders may continue to wage the “war on rats” while improving existing strategies within this paradigm. Key path...

Research paper thumbnail of Stakeholder perspectives on the development and implementation of approaches to municipal rat management

Journal of Urban Ecology, 2021

Rats evoke public health and economic concern in cities globally. Rapid urbanization exacerbates ... more Rats evoke public health and economic concern in cities globally. Rapid urbanization exacerbates pre-existing rat problems, requiring the development and adoption of more effective methods of prevention, monitoring and mitigation. While previous studies have indicated that city-wide municipal management approaches often fail, such outcomes are often left without specific explanation. To determine how municipalities could more effectively develop and implement large-scale approaches, we interviewed stakeholders in municipal rat management programs to document their opinions, recommendations and the challenges they face. Using a thematic framework method, this study collates and analyzes in-depth interviews with 39 stakeholders from seven cities across the United States. Overall, stakeholders’ recommendations for municipal rat management aligned with many conceptual attributes of effective management reported in the literature. Specifically, stakeholders highlighted the need to priori...

Research paper thumbnail of Routine prenatal screening for HIV in a low-prevalence setting reduces the rate of maternal–fetal HIV transmission and may rival other widely accepted healthcare expenditures in terms of cost effectiveness

Evidence-based Healthcare, 1999

Background: The objectives of this study were to assess the effect of British Columbia's June 199... more Background: The objectives of this study were to assess the effect of British Columbia's June 1994 guidelines for prenatal HIV screening on the rate of maternalfetal HIV transmission and to estimate the cost-effectiveness of such screening. Methods: The authors conducted a retrospective review of pregnancy and delivery statistics, HIV screening practices, laboratory testing volume, prenatal and labour management decisions of HIV-positive women, maternal-fetal transmission rates and associated costs. Results: Over 1995 and 1996, 135 681 women were pregnant and 92 645 carried to term. The rate of HIV testing increased from 55% to 76% of pregnancies on chart review at one hospital between November 1995 and November 1996. On the basis of seroprevalence studies, an estimated 50.2 pregnancies and 34.3 (95% confidence interval 17.6 to 51.0) live births to HIV-positive women were expected. Of 42 identified mother-infant pairs with an estimated date of delivery during 1995 or 1996, 25 were known only through screening. Of these 25 cases, there were 10 terminations, 1 spontaneous abortion and 14 cases in which the woman elected to carry the pregnancy to term with antiretroviral therapy. There was one stillbirth. One instance of maternal-fetal HIV transmission occurred among the 13 live births. The net savings attributable to prevented infections among babies carried to term were 165586,withasavingperpreventedcaseof165 586, with a saving per prevented case of 165586,withasavingperpreventedcaseof75 266. Interpretation: A routine offer of pregnancy screening for HIV in a low-prevalence setting reduces the rate of maternal-fetal HIV transmission and may rival other widely accepted health care expenditures in terms of cost-effectiveness. Résumé Contexte : Cette étude visait à évaluer l'effet des lignes directrices relatives au dépistage prénatal du VIH adoptées en juin 1994 par la Colombie-Britannique sur le taux de transmission du VIH de la mère au foetus et à évaluer l'efficacité des coûts du dépistage. Méthodes : Les auteurs ont procédé à une étude rétrospective des statistiques sur la grossesse et l'accouchement, des pratiques de dépistage du VIH, du volume des tests de laboratoire, des décisions relatives au suivi prénatal et à la prise en charge du travail de femmes infectées par le VIH, des taux de transmission de la mère au foetus et des coûts connexes. Résultats : En 1995 et 1996, 135 681 femmes étaient enceintes et 92 645 ont accouché à terme. Un examen des dossiers réalisé à un hôpital entre novembre 1995 et novembre 1996 révèle que le taux des tests de dépistage du VIH est passé de 55 % à 76 % des grossesses. D'après les études de séroprévalence, on estimait attendre 50,2 grossesses et 34,3 (intervalle de confiance à 95 % de 17,6 à 51,0) naissances vivantes chez les femmes infectées par le VIH. Sur 42 paires mère-nourrisson identifiées dont la date prévue d'accouchement se situait en 1995 ou 1996, 25 cas ont été repérés par le dépistage seulement. Parmi ces 25 cas, il y a eu 10 avortements, un avortement spontané et 14 cas où la femme a

Research paper thumbnail of Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective population-based cohort study

BMJ Open, Aug 1, 2020

et al. Determining the long-term health burden and risk of sequelae for 14 foodborne infections i... more et al. Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective populationbased cohort study. BMJ Open 2020;10:e036560.

Research paper thumbnail of Improving the response to future pandemics requires an improved understanding of the role played by institutions, politics, organization, and governance

PLOS Global Public Health

Research paper thumbnail of Investigating SARS-CoV-2 infection and the health and psychosocial impact of the COVID-19 pandemic in the Canadian CHILD Cohort: study methodology and cohort profile

medRxiv (Cold Spring Harbor Laboratory), Oct 21, 2022

doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by pee... more doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

Research paper thumbnail of Organ dysfunction and death in patients admitted to hospital with COVID-19 in pandemic waves 1 to 3 in British Columbia, Ontario and Quebec, Canada: a cohort study

CMAJ Open

T here have been 5 waves of the COVID-19 pandemic in Canada, including the omicron-driven wave (a... more T here have been 5 waves of the COVID-19 pandemic in Canada, including the omicron-driven wave (as of Dec. 17, 2021 1). Mortality from COVID-19 varied as the waves moved across the world, and changes in patient mix, the emergence of successful treatment and improvements in quality of care affected acute COVID-19 mortality. Some studies showed decreased mortality after wave 1. 2,3 In a 43-country study, 3 there was lower mortality in wave 2 than in wave 1. Domingo and colleagues 4 found higher mortality among patients in Spain in wave 1 than in wave 2 that was explained by differences in intensive care unit (ICU) admission and ventilation use. In another study, with data from 14 countries that each had at least 4000 deaths from COVID-19 as of Jan. 14, 2021, the age distribution of those who died was similar between waves 1 and 2, but there were fewer deaths among nursing home residents in wave 2. 5 More use of anticoagulation and corticosteroids in wave 2 may explain the lower mortality. 6 In Spain, patients from wave 2 were more

Research paper thumbnail of Incidence of invasive pneumococcal disease after introduction of the 13-valent conjugate pneumococcal vaccine in British Columbia: A retrospective cohort study

PLOS ONE, 2020

Background A significant reduction in invasive pneumococcal disease (IPD) has been reported, acro... more Background A significant reduction in invasive pneumococcal disease (IPD) has been reported, across all ages, following the implementation of 7-valent conjugate pneumococcal vaccine (PCV7) globally, as part of infant immunization programs. We explored the additional impact of PCV13 on IPD over a 14-year period. Methods Using provincial laboratory surveillance and hospitalization data (N = 5791), we calculated the annual incidence of IPD following the implementation of PCV13 vaccine. Poisson regression was used to evaluate changes in the overall incidence of IPD, and serotype-specific IPD between PCV7 (2004-10) and PCV13 (2011-2015) eras. Results Overall, IPD rates have seen a modest decline in the PCV13 compared to the PCV7 era (IRR 0.84; 95% CI: 0.79-0.89); this was seen in children �2 years of age, and the majority of the adult cohort. Rates of vaccine-type IPD (PCV7 and PCV13) also decreased in the PCV13 era. In contrast, IPD incidence related to non-PCV13 (IRR: 1.56; 95%CI:1.43-1.72) and non-vaccine serotypes (IRR: 2.12; 95%CI:1.84-2.45) increased in the PCV13 era compared to the PCV7 era. Conclusions A modest reduction in IPD from the PCV13 vaccine was observed, with gains limited to the immunized cohort and adults. However, a significant increase in non-vaccine serotypes emphasizes the need for continued surveillance.

Research paper thumbnail of Comparative single-dose mRNA and ChAdOx1 vaccine effectiveness against SARS-CoV-2, including early variants of concern: a test-negative design, British Columbia, Canada

ABSTRACTIntroductionIn randomized controlled trials, single-dose efficacy against SARS-CoV-2 illn... more ABSTRACTIntroductionIn randomized controlled trials, single-dose efficacy against SARS-CoV-2 illness exceeded 90% for mRNA vaccines (BNT162b2 and mRNA-1273), and 75% for ChAdOx1. In British Columbia (BC), Canada second doses were deferred up to 16 weeks and ChAdOx1 was only initially recommended for adults 55 years of age and older. We compared single-dose vaccine effectiveness (VE) during the spring 2021 wave in BC when Alpha and Gamma variants of concern (VOC) predominated.MethodsVE was estimated against infection and hospitalization by test-negative design: cases were RT-PCR test-positive for SARS-CoV-2 and controls were test-negative. Adults 50-69 years old with specimen collection between April 4 and May 22 (weeks 14-20) were included. Variant-specific VE was estimated between weeks 17-20 when genetic characterization of all case viruses was performed, primarily through whole genome sequencing.ResultsVE analyses included 7,116 (10%) cases and 60,958 controls. Three-quarters of ...

Research paper thumbnail of Governing antimicrobial resistance: a narrative review of global governance mechanisms

Journal of Public Health Policy, 2020

Antimicrobial resistance (AMR), a central health challenge of the twenty first century, poses sub... more Antimicrobial resistance (AMR), a central health challenge of the twenty first century, poses substantial population health risks, with deaths currently estimated to be around 700,000 per year globally. The international community has signaled its commitment to exploring and implementing effective policy responses to AMR, with a Global Action Plan on AMR approved by the World Health Assembly in 2015. Major governance challenges could thwart collective efforts to address AMR, along with limited knowledge about how to design effective global governance mechanisms. To identify common ground for more coordinated global actions we conducted a narrative review to map dominant ideas and academic debates about AMR governance. We found two categories of global governance mechanisms: binding and non-binding and discuss advantages and drawbacks of each. We suggest that a combination of non-binding and binding governance mechanisms supported by leading antimicrobial use countries and important AMR stakeholders, and informed by One Health principles, may be best suited to tackle AMR.

Research paper thumbnail of Open drug discovery of anti-virals critical for Canada’s pandemic strategy

FACETS, 2020

In the event of the current COVID-19 pandemic and in preparation for future pandemics, open scien... more In the event of the current COVID-19 pandemic and in preparation for future pandemics, open science can support mission-oriented research and development, as well as commercialization. Open science shares skills and resources across sectors; avoids duplication and provides the basis for rapid and effective validation due to full transparency. It is a strategy that can adjust quickly to reflect changing incentives and priorities, because it does not rely on any one actor or sector. While eschewing patents, it can ensure high-quality drugs, low pricing, and access through existing regulatory mechanisms. Open science practices and partnerships decrease transaction costs, increase diversity of actors, reduce overall costs, open new, higher-risk/higher-impact approaches to research, and provide entrepreneurs freedom to operate and freedom to innovate. We argue that it is time to re-open science, not only in its now restricted arena of fundamental research, but throughout clinical transla...

Research paper thumbnail of 221. Comparison of dental antibiotic prescribing between Australia, England, the United States and British Columbia in 2017

Open Forum Infectious Diseases, 2020

Background Antibiotic resistance is recognised as a major public health burden. Dentists overpres... more Background Antibiotic resistance is recognised as a major public health burden. Dentists overprescribe antibiotics and prescribe for unnecessary indications. Tracking and investigating prescribing practices by healthcare professionals provides insights needed to inform targeted antibiotic stewardship interventions. It is unclear how dental antibiotic prescribing patterns differs between countries. The aim of this study was to compare antibiotic prescribing by dentists in Australia, England the United States (US) and British Columbia (BC). Methods This was a cross-sectional study of dispensed dental antibiotic prescriptions between January 1 and December 31, 2017, from Australia, England, US and BC. Dispensed dental antibiotic prescriptions included those from outpatient pharmacies and healthcare settings. Outcome measures included the proportion of dental antibiotic prescriptions by location and prescribing rates by population. Results English dentists prescribed 1.6 times more anti...

Research paper thumbnail of Sustained Dysregulation of the Plasma Renin-angiotensin System in Acute COVID-19

SARS-CoV-2 enters cells by binding to angiotensin-converting enzyme 2 (ACE2), and COVID-19 infect... more SARS-CoV-2 enters cells by binding to angiotensin-converting enzyme 2 (ACE2), and COVID-19 infection may therefore induce changes in the renin-angiotensin system (RAS). To determine the effects of COVID-19 on plasma RAS components, we measured plasma ACE, ACE2, and angiotensins I, (1-7), and II in 46 adults with COVID-19 at hospital admission and on days 2, 4, 7 and 14, compared to 50 blood donors (controls). We compared survivors vs. non-survivors, males vs. females, ventilated vs. not ventilated, and angiotensin receptor blocker (ARB) and angiotensin-converting enzyme (ACE) inhibitor-exposed vs. not exposed. At admission, COVID-19 patients had higher plasma levels of ACE (p=0.012), ACE2 (p=0.001) and angiotensin-(1-7) (p<0.001) than controls. Plasma ACE and ACE2 remained elevated for 14 days in COVID-19 patients, while plasma angiotensin-(1-7) decreased after 7 days. In adjusted analyses, plasma ACE was higher in males vs. females (p=0.042), and plasma angiotensin I was signifi...

Research paper thumbnail of International Health: Five Reasons Why Canadians Should Get Involved

Canadian Journal of Public Health, 2003

hy should Canadians get involved in international health projects that seem to take them away fro... more hy should Canadians get involved in international health projects that seem to take them away from their patients and programs in Canada? Why should taxpayers fund such projects? We present five reasons why international health should be a priority for Canadians.

Research paper thumbnail of Demographics, Sexual Risk Behaviours and Uptake of Screening for Sexually Transmitted Infections among Attendees of a Weekly Women-only Community Clinic Program

Canadian Journal of Public Health, 2008

Objectives: Vancouver's DTES represents a high-risk neighbourhood, in which there exist a number ... more Objectives: Vancouver's DTES represents a high-risk neighbourhood, in which there exist a number of community clinics and outreach programs. The purpose of this study was twofold: 1) to describe the population of women attending a weekly women's program with respect to demographics, risk behaviours and prevalence of STI, and 2) to assess the uptake of STI screening in this setting. Methods: A cross-sectional survey was undertaken during a weekly community clinicbased women's program from October to December, 2004. Women were recruited at the start of the program each week and were invited to provide urine samples for chlamydia and gonorrhea screening. Results: Among 126 respondents, the median age was 42 (36-49), more than half (52%) self-identified as White and 40% as Aboriginal ethnicity. Forty percent were currently involved in the sex trade. Two thirds reported a Pap smear in the past year, while 14% had not accessed sexual health care (Pap smear, STI or HIV testing). Among the 92/126 (74%) women providing a urine sample, the prevalence of chlamydia and gonorrhea was 2.2% and 0.0%, respectively. Conclusion: The majority of women accessing this program were over 35 years of age, and while nearly half were currently involved in the sex trade, cross-sectional screening did not reveal a substantial prevalence of STIs. Women who were not regular program attendees reported less sexual health care, and represented the only two cases of chlamydia found. Innovative programs that better serve the needs of populations that remain unable or unwilling to seek sexual health care in its current formats are needed.

Research paper thumbnail of A novel method for affixing Global Positioning System (GPS) tags to urban Norway rats (Rattus norvegicus): feasibility, health impacts and potential for tracking movement

Journal of Urban Ecology, 2017

Despite the ubiquity of rats, we lack an understanding of how they move within the urban environm... more Despite the ubiquity of rats, we lack an understanding of how they move within the urban environment. Traditional tools for studying rat movement, such as capture-mark-recapture, are time-intensive and provide coarse movement estimates. Alternative methods, such as continuous tracking by radio-telemetry are difficult to employ in cities where buildings may obstruct radio signals. Global Positioning System (GPS) tags are a promising alternative for resolving fine-scale movement patterns. To test the utility of GPS tracking for urban rats, we affixed tags to 14 sexually mature Norway rats (Rattus norvegicus) in Vancouver, Canada, using veterinary adhesive and absorbable sutures. Six GPS tags had remote-download capabilities and eight stored location data downloadable upon tag recovery. We did not acquire location data from either tag type. While the data receiver successfully recognized five of six remote-download tags, these tags had not stored any locations. Further, of the three recaptured rats (21.4%), all had dislodged tags, although there were no observable adverse health effects from tag attachment. Given low recapture success, our results suggest that remote-download technologies offer greater potential for data recovery. That remote-download tags did not record locations could be due to obstruction of tag line-of-sight with a satellite either through rat ecology (e.g. burrowing), and/or removal in obstructed areas. Future technological advancements, such as surgically implantable tags that hinder removal, may improve the potential use of GPS tags to track urban rat movement. This information is essential to develop effective rat control strategies and mitigate future rat-related public health concerns.

Research paper thumbnail of 1118. Trends of Paediatric Prescribing for Common Infections in British Columbia

Open Forum Infectious Diseases, Oct 1, 2019

Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine a... more Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine antibiogram, and an EMR BPA successfully reduced BSA and increased NSA for treatment of uncomplicated UTIs.

Research paper thumbnail of 2705. Serotype Replacement Following Childhood Pneumococcal Conjugate Vaccination Programs in British Columbia, Canada

Open Forum Infectious Diseases, Oct 1, 2019

recommendations, were prospectively enrolled through 45 general pediatric practice facilities in ... more recommendations, were prospectively enrolled through 45 general pediatric practice facilities in 30 municipalities in Greece. A single oropharyngeal sample was obtained from each subject in a standardized manner (questionnaire, procedure). Based on the time interval since the fourth dose of PCV13, the children sampled were grouped for analysis in 6 groups: 26 days to 11 months; 12-23 months; 24-35 months; 36-47 months; 48-59 months, and 60-71 months. Carriage and distribution of Streptococcus pneumoniae serotypes was detected by RT-PCR. Results: A total of 1212 children aged 14-83 months were investigated. S. pneumoniae was identified in the pharyngeal swab of 617 children (50.9%); 172/617 (27.9%) children carried > 1 pneumococcal serotypes. As a consequence of co-colonization, a total number of 718 S. pneumoniae (belonging to 28 serotypes) was identified. The carriage rate of non-PCV13 serotypes escalated within 3 years after the fourth dose and plateaued during the fourth and fifth year. The carriage rate of PCV13 serotypes escalated during the 4 years after the fourth dose and declined thereafter. 22/305 children (7.2%) carried one or more PCV13 serotypes in the first year after the fourth vaccine dose, 27/201 (13.4%) in the second year, 34/207 (16.4%) in the third year, 48/224 (21.4%) in the fourth year, 40/191 (20.9%) in the fifth year and 13/84 (15.5%) in the sixth year (P < 0.0001) (Figure 1). The colonization frequency of serotypes 3 and 19A increased with the rise of the vaccination time interval (Figure 2). Changes in the frequency of other PCV13 serotypes were not significant. Serotypes 7F, 14 and 23F were not recovered. Conclusion: Our study suggests that S. pneumoniae is present in the pharynx of children 26 days to 71 months after the completion of PCV13 vaccination, and that non-PCV13 serotypes predominate throughout this period. The carriage rate of PCV13 serotypes 3 and 19A increases significantly as the time interval from the fourth dose of PCV13 increases.

Research paper thumbnail of 1117. A Retrospective Analysis of Paediatric Prescribing in British Columbia from 2013 to 2016

Open Forum Infectious Diseases, Oct 1, 2019

Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine a... more Conclusion. A multimodal stewardship intervention using a pocket card with guidelines and urine antibiogram, and an EMR BPA successfully reduced BSA and increased NSA for treatment of uncomplicated UTIs.

Research paper thumbnail of Nasopharyngeal Angiotensin Converting Enzyme 2 (ACE2) Expression as a Risk-Factor for SARS-CoV-2 Transmission in Concurrent Hospital Associated Outbreaks

BackgroundWidespread human-to-human transmission of the severe acute respiratory syndrome coronav... more BackgroundWidespread human-to-human transmission of the severe acute respiratory syndrome coronavirus two (SARS-CoV-2) stems from a strong affinity for the cellular receptor angiotensin converting enzyme two (ACE2). We investigate the relationship between a patient’s nasopharyngealACE2transcription and secondary transmission within a series of concurrent hospital associated SARS-CoV-2 outbreaks in British Columbia, Canada.MethodsEpidemiological case data from the outbreak investigations was merged with public health laboratory records and viral lineage calls, from whole genome sequencing, to reconstruct the concurrent outbreaks using infection tracing transmission network analysis.ACE2transcription and RNA viral load were measured by quantitative real-time polymerase chain reaction. The transmission network was resolved to calculate the number of potential secondary cases. Bivariate and multivariable analyses using Poisson and Negative Binomial regression models was performed to est...

Research paper thumbnail of Reconsidering the “War on Rats”: What We Know From Over a Century of Research Into Municipal Rat Management

Frontiers in Ecology and Evolution, 2022

To sustainably control urban rat infestations, management efforts need to encompass large areas o... more To sustainably control urban rat infestations, management efforts need to encompass large areas of urban centers. Therefore, the objective of this review and narrative synthesis was to collate what is known about municipal-scale rat management. We explored the management frameworks that have been used at a large scale in cities and we describe the expectations of experts who have designed and implemented these frameworks. We found that there has been a persistent “war on rats” paradigm driving this literature since the early 1900s. Not only was there little quantitative evidence to support this paradigm and associated methodologies, but together, they failed to meet the expectations of those who designed and implemented them due to real-world constraints (i.e., limited resources). To improve the field of municipal management, we identify two distinct options. First, stakeholders may continue to wage the “war on rats” while improving existing strategies within this paradigm. Key path...

Research paper thumbnail of Stakeholder perspectives on the development and implementation of approaches to municipal rat management

Journal of Urban Ecology, 2021

Rats evoke public health and economic concern in cities globally. Rapid urbanization exacerbates ... more Rats evoke public health and economic concern in cities globally. Rapid urbanization exacerbates pre-existing rat problems, requiring the development and adoption of more effective methods of prevention, monitoring and mitigation. While previous studies have indicated that city-wide municipal management approaches often fail, such outcomes are often left without specific explanation. To determine how municipalities could more effectively develop and implement large-scale approaches, we interviewed stakeholders in municipal rat management programs to document their opinions, recommendations and the challenges they face. Using a thematic framework method, this study collates and analyzes in-depth interviews with 39 stakeholders from seven cities across the United States. Overall, stakeholders’ recommendations for municipal rat management aligned with many conceptual attributes of effective management reported in the literature. Specifically, stakeholders highlighted the need to priori...

Research paper thumbnail of Routine prenatal screening for HIV in a low-prevalence setting reduces the rate of maternal–fetal HIV transmission and may rival other widely accepted healthcare expenditures in terms of cost effectiveness

Evidence-based Healthcare, 1999

Background: The objectives of this study were to assess the effect of British Columbia's June 199... more Background: The objectives of this study were to assess the effect of British Columbia's June 1994 guidelines for prenatal HIV screening on the rate of maternalfetal HIV transmission and to estimate the cost-effectiveness of such screening. Methods: The authors conducted a retrospective review of pregnancy and delivery statistics, HIV screening practices, laboratory testing volume, prenatal and labour management decisions of HIV-positive women, maternal-fetal transmission rates and associated costs. Results: Over 1995 and 1996, 135 681 women were pregnant and 92 645 carried to term. The rate of HIV testing increased from 55% to 76% of pregnancies on chart review at one hospital between November 1995 and November 1996. On the basis of seroprevalence studies, an estimated 50.2 pregnancies and 34.3 (95% confidence interval 17.6 to 51.0) live births to HIV-positive women were expected. Of 42 identified mother-infant pairs with an estimated date of delivery during 1995 or 1996, 25 were known only through screening. Of these 25 cases, there were 10 terminations, 1 spontaneous abortion and 14 cases in which the woman elected to carry the pregnancy to term with antiretroviral therapy. There was one stillbirth. One instance of maternal-fetal HIV transmission occurred among the 13 live births. The net savings attributable to prevented infections among babies carried to term were 165586,withasavingperpreventedcaseof165 586, with a saving per prevented case of 165586,withasavingperpreventedcaseof75 266. Interpretation: A routine offer of pregnancy screening for HIV in a low-prevalence setting reduces the rate of maternal-fetal HIV transmission and may rival other widely accepted health care expenditures in terms of cost-effectiveness. Résumé Contexte : Cette étude visait à évaluer l'effet des lignes directrices relatives au dépistage prénatal du VIH adoptées en juin 1994 par la Colombie-Britannique sur le taux de transmission du VIH de la mère au foetus et à évaluer l'efficacité des coûts du dépistage. Méthodes : Les auteurs ont procédé à une étude rétrospective des statistiques sur la grossesse et l'accouchement, des pratiques de dépistage du VIH, du volume des tests de laboratoire, des décisions relatives au suivi prénatal et à la prise en charge du travail de femmes infectées par le VIH, des taux de transmission de la mère au foetus et des coûts connexes. Résultats : En 1995 et 1996, 135 681 femmes étaient enceintes et 92 645 ont accouché à terme. Un examen des dossiers réalisé à un hôpital entre novembre 1995 et novembre 1996 révèle que le taux des tests de dépistage du VIH est passé de 55 % à 76 % des grossesses. D'après les études de séroprévalence, on estimait attendre 50,2 grossesses et 34,3 (intervalle de confiance à 95 % de 17,6 à 51,0) naissances vivantes chez les femmes infectées par le VIH. Sur 42 paires mère-nourrisson identifiées dont la date prévue d'accouchement se situait en 1995 ou 1996, 25 cas ont été repérés par le dépistage seulement. Parmi ces 25 cas, il y a eu 10 avortements, un avortement spontané et 14 cas où la femme a

Research paper thumbnail of Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective population-based cohort study

BMJ Open, Aug 1, 2020

et al. Determining the long-term health burden and risk of sequelae for 14 foodborne infections i... more et al. Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective populationbased cohort study. BMJ Open 2020;10:e036560.

Research paper thumbnail of Improving the response to future pandemics requires an improved understanding of the role played by institutions, politics, organization, and governance

PLOS Global Public Health

Research paper thumbnail of Investigating SARS-CoV-2 infection and the health and psychosocial impact of the COVID-19 pandemic in the Canadian CHILD Cohort: study methodology and cohort profile

medRxiv (Cold Spring Harbor Laboratory), Oct 21, 2022

doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by pee... more doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

Research paper thumbnail of Organ dysfunction and death in patients admitted to hospital with COVID-19 in pandemic waves 1 to 3 in British Columbia, Ontario and Quebec, Canada: a cohort study

CMAJ Open

T here have been 5 waves of the COVID-19 pandemic in Canada, including the omicron-driven wave (a... more T here have been 5 waves of the COVID-19 pandemic in Canada, including the omicron-driven wave (as of Dec. 17, 2021 1). Mortality from COVID-19 varied as the waves moved across the world, and changes in patient mix, the emergence of successful treatment and improvements in quality of care affected acute COVID-19 mortality. Some studies showed decreased mortality after wave 1. 2,3 In a 43-country study, 3 there was lower mortality in wave 2 than in wave 1. Domingo and colleagues 4 found higher mortality among patients in Spain in wave 1 than in wave 2 that was explained by differences in intensive care unit (ICU) admission and ventilation use. In another study, with data from 14 countries that each had at least 4000 deaths from COVID-19 as of Jan. 14, 2021, the age distribution of those who died was similar between waves 1 and 2, but there were fewer deaths among nursing home residents in wave 2. 5 More use of anticoagulation and corticosteroids in wave 2 may explain the lower mortality. 6 In Spain, patients from wave 2 were more

Research paper thumbnail of Incidence of invasive pneumococcal disease after introduction of the 13-valent conjugate pneumococcal vaccine in British Columbia: A retrospective cohort study

PLOS ONE, 2020

Background A significant reduction in invasive pneumococcal disease (IPD) has been reported, acro... more Background A significant reduction in invasive pneumococcal disease (IPD) has been reported, across all ages, following the implementation of 7-valent conjugate pneumococcal vaccine (PCV7) globally, as part of infant immunization programs. We explored the additional impact of PCV13 on IPD over a 14-year period. Methods Using provincial laboratory surveillance and hospitalization data (N = 5791), we calculated the annual incidence of IPD following the implementation of PCV13 vaccine. Poisson regression was used to evaluate changes in the overall incidence of IPD, and serotype-specific IPD between PCV7 (2004-10) and PCV13 (2011-2015) eras. Results Overall, IPD rates have seen a modest decline in the PCV13 compared to the PCV7 era (IRR 0.84; 95% CI: 0.79-0.89); this was seen in children �2 years of age, and the majority of the adult cohort. Rates of vaccine-type IPD (PCV7 and PCV13) also decreased in the PCV13 era. In contrast, IPD incidence related to non-PCV13 (IRR: 1.56; 95%CI:1.43-1.72) and non-vaccine serotypes (IRR: 2.12; 95%CI:1.84-2.45) increased in the PCV13 era compared to the PCV7 era. Conclusions A modest reduction in IPD from the PCV13 vaccine was observed, with gains limited to the immunized cohort and adults. However, a significant increase in non-vaccine serotypes emphasizes the need for continued surveillance.

Research paper thumbnail of Comparative single-dose mRNA and ChAdOx1 vaccine effectiveness against SARS-CoV-2, including early variants of concern: a test-negative design, British Columbia, Canada

ABSTRACTIntroductionIn randomized controlled trials, single-dose efficacy against SARS-CoV-2 illn... more ABSTRACTIntroductionIn randomized controlled trials, single-dose efficacy against SARS-CoV-2 illness exceeded 90% for mRNA vaccines (BNT162b2 and mRNA-1273), and 75% for ChAdOx1. In British Columbia (BC), Canada second doses were deferred up to 16 weeks and ChAdOx1 was only initially recommended for adults 55 years of age and older. We compared single-dose vaccine effectiveness (VE) during the spring 2021 wave in BC when Alpha and Gamma variants of concern (VOC) predominated.MethodsVE was estimated against infection and hospitalization by test-negative design: cases were RT-PCR test-positive for SARS-CoV-2 and controls were test-negative. Adults 50-69 years old with specimen collection between April 4 and May 22 (weeks 14-20) were included. Variant-specific VE was estimated between weeks 17-20 when genetic characterization of all case viruses was performed, primarily through whole genome sequencing.ResultsVE analyses included 7,116 (10%) cases and 60,958 controls. Three-quarters of ...

Research paper thumbnail of Governing antimicrobial resistance: a narrative review of global governance mechanisms

Journal of Public Health Policy, 2020

Antimicrobial resistance (AMR), a central health challenge of the twenty first century, poses sub... more Antimicrobial resistance (AMR), a central health challenge of the twenty first century, poses substantial population health risks, with deaths currently estimated to be around 700,000 per year globally. The international community has signaled its commitment to exploring and implementing effective policy responses to AMR, with a Global Action Plan on AMR approved by the World Health Assembly in 2015. Major governance challenges could thwart collective efforts to address AMR, along with limited knowledge about how to design effective global governance mechanisms. To identify common ground for more coordinated global actions we conducted a narrative review to map dominant ideas and academic debates about AMR governance. We found two categories of global governance mechanisms: binding and non-binding and discuss advantages and drawbacks of each. We suggest that a combination of non-binding and binding governance mechanisms supported by leading antimicrobial use countries and important AMR stakeholders, and informed by One Health principles, may be best suited to tackle AMR.

Research paper thumbnail of Open drug discovery of anti-virals critical for Canada’s pandemic strategy

FACETS, 2020

In the event of the current COVID-19 pandemic and in preparation for future pandemics, open scien... more In the event of the current COVID-19 pandemic and in preparation for future pandemics, open science can support mission-oriented research and development, as well as commercialization. Open science shares skills and resources across sectors; avoids duplication and provides the basis for rapid and effective validation due to full transparency. It is a strategy that can adjust quickly to reflect changing incentives and priorities, because it does not rely on any one actor or sector. While eschewing patents, it can ensure high-quality drugs, low pricing, and access through existing regulatory mechanisms. Open science practices and partnerships decrease transaction costs, increase diversity of actors, reduce overall costs, open new, higher-risk/higher-impact approaches to research, and provide entrepreneurs freedom to operate and freedom to innovate. We argue that it is time to re-open science, not only in its now restricted arena of fundamental research, but throughout clinical transla...

Research paper thumbnail of 221. Comparison of dental antibiotic prescribing between Australia, England, the United States and British Columbia in 2017

Open Forum Infectious Diseases, 2020

Background Antibiotic resistance is recognised as a major public health burden. Dentists overpres... more Background Antibiotic resistance is recognised as a major public health burden. Dentists overprescribe antibiotics and prescribe for unnecessary indications. Tracking and investigating prescribing practices by healthcare professionals provides insights needed to inform targeted antibiotic stewardship interventions. It is unclear how dental antibiotic prescribing patterns differs between countries. The aim of this study was to compare antibiotic prescribing by dentists in Australia, England the United States (US) and British Columbia (BC). Methods This was a cross-sectional study of dispensed dental antibiotic prescriptions between January 1 and December 31, 2017, from Australia, England, US and BC. Dispensed dental antibiotic prescriptions included those from outpatient pharmacies and healthcare settings. Outcome measures included the proportion of dental antibiotic prescriptions by location and prescribing rates by population. Results English dentists prescribed 1.6 times more anti...

Research paper thumbnail of Sustained Dysregulation of the Plasma Renin-angiotensin System in Acute COVID-19

SARS-CoV-2 enters cells by binding to angiotensin-converting enzyme 2 (ACE2), and COVID-19 infect... more SARS-CoV-2 enters cells by binding to angiotensin-converting enzyme 2 (ACE2), and COVID-19 infection may therefore induce changes in the renin-angiotensin system (RAS). To determine the effects of COVID-19 on plasma RAS components, we measured plasma ACE, ACE2, and angiotensins I, (1-7), and II in 46 adults with COVID-19 at hospital admission and on days 2, 4, 7 and 14, compared to 50 blood donors (controls). We compared survivors vs. non-survivors, males vs. females, ventilated vs. not ventilated, and angiotensin receptor blocker (ARB) and angiotensin-converting enzyme (ACE) inhibitor-exposed vs. not exposed. At admission, COVID-19 patients had higher plasma levels of ACE (p=0.012), ACE2 (p=0.001) and angiotensin-(1-7) (p<0.001) than controls. Plasma ACE and ACE2 remained elevated for 14 days in COVID-19 patients, while plasma angiotensin-(1-7) decreased after 7 days. In adjusted analyses, plasma ACE was higher in males vs. females (p=0.042), and plasma angiotensin I was signifi...

Research paper thumbnail of International Health: Five Reasons Why Canadians Should Get Involved

Canadian Journal of Public Health, 2003

hy should Canadians get involved in international health projects that seem to take them away fro... more hy should Canadians get involved in international health projects that seem to take them away from their patients and programs in Canada? Why should taxpayers fund such projects? We present five reasons why international health should be a priority for Canadians.

Research paper thumbnail of Demographics, Sexual Risk Behaviours and Uptake of Screening for Sexually Transmitted Infections among Attendees of a Weekly Women-only Community Clinic Program

Canadian Journal of Public Health, 2008

Objectives: Vancouver's DTES represents a high-risk neighbourhood, in which there exist a number ... more Objectives: Vancouver's DTES represents a high-risk neighbourhood, in which there exist a number of community clinics and outreach programs. The purpose of this study was twofold: 1) to describe the population of women attending a weekly women's program with respect to demographics, risk behaviours and prevalence of STI, and 2) to assess the uptake of STI screening in this setting. Methods: A cross-sectional survey was undertaken during a weekly community clinicbased women's program from October to December, 2004. Women were recruited at the start of the program each week and were invited to provide urine samples for chlamydia and gonorrhea screening. Results: Among 126 respondents, the median age was 42 (36-49), more than half (52%) self-identified as White and 40% as Aboriginal ethnicity. Forty percent were currently involved in the sex trade. Two thirds reported a Pap smear in the past year, while 14% had not accessed sexual health care (Pap smear, STI or HIV testing). Among the 92/126 (74%) women providing a urine sample, the prevalence of chlamydia and gonorrhea was 2.2% and 0.0%, respectively. Conclusion: The majority of women accessing this program were over 35 years of age, and while nearly half were currently involved in the sex trade, cross-sectional screening did not reveal a substantial prevalence of STIs. Women who were not regular program attendees reported less sexual health care, and represented the only two cases of chlamydia found. Innovative programs that better serve the needs of populations that remain unable or unwilling to seek sexual health care in its current formats are needed.