Search

Background: Population-based cross-sectional serosurveys within the Lower Mainland, British Columbia, Canada, showed about 10%, 40% and 60% of residents were infected with SARS-CoV-2 by the sixth (September 2021), seventh (March 2022) and eighth (July 2022) serosurveys. We conducted the ninth (December 2022) and tenth (July 2023) serosurveys and sought to assess risk of severe outcomes from a first-ever SARS-CoV-2 infection during intersurvey periods. Methods: Using increments in cumulative infection-induced seroprevalence, population census, discharge abstract and vital statistics data sets, we estimated infection hospitalization and fatality ratios (IHRs and IFRs) by age and sex for the sixth to seventh (Delta/Omicron-BA.1), seventh to eighth (Omicron-BA.2/BA.5) and eighth to ninth (Omicron-BA.5/BQ.1) intersurvey periods. As derived, IHR and IFR estimates represent the risk of severe outcome from a first-ever SARS-CoV-2 infection acquired during the specified intersurvey period. Results: The cumulative infection-induced seroprevalence was 74% by December 2022 and 79% by July 2023, exceeding 80% among adults younger than 50 years but remaining less than 60% among those aged 80 years and older. Period-specific IHR and IFR estimates were consistently less than 0.3% and 0.1% overall. By age group, IHR and IFR estimates were less than 1.0% and up to 0.1%, respectively, except among adults aged 70–79 years during the sixth to seventh intersurvey period (IHR 3.3% and IFR 1.0%) and among those aged 80 years and older during all periods (IHR 4.7%, 2.2% and 3.5%; IFR 3.3%, 0.6% and 1.3% during the sixth to seventh, seventh to eighth and eighth to ninth periods, respectively). The risk of severe outcome followed a J-shaped age pattern. During the eighth to ninth period, we estimated about 1 hospital admission for COVID-19 per 300 newly infected children younger than 5 years versus about 1 per 30 newly infected adults aged 80 years and older, with no deaths from COVID-19 among children but about 1 death per 80 newly infected adults aged 80 years and older during that period. Interpretation: By July 2023, we estimated about 80% of residents in the Lower Mainland, BC, had been infected with SARS-CoV-2 overall, with low risk of hospital admission or death; about 40% of the oldest adults, however, remained uninfected and at highest risk of a severe outcome. First infections among older adults may still contribute substantial burden from COVID-19, reinforcing the need to continue to prioritize this age group for vaccination and to consider them in health care system planning. [ABSTRACT FROM AUTHOR]

Background: The evolving proportion of the population considered immunologically naive versus primed for more efficient immune memory response to SARS-CoV-2 has implications for risk assessment. We sought to chronicle vaccine- and infection-induced seroprevalence across the first 7 waves of the COVID-19 pandemic in British Columbia, Canada. Methods: During 8 cross-sectional serosurveys conducted between March 2020 and August 2022, we obtained anonymized residual sera from children and adults who attended an outpatient laboratory network in the Lower Mainland (Greater Vancouver and Fraser Valley). We used at least 3 immunoassays per serosurvey to detect SARS-CoV-2 spike and nucleocapsid antibodies. We assessed any seroprevalence (vaccineor infection-induced, or both), defined by positivity on any 2 assays, and infection-induced seroprevalence, also defined by dual-assay positivity but requiring both antinucleocapsid and antispike detection. We used estimates of infection-induced seroprevalence to explore underascertainment of infections by surveillance case reports. Results: By January 2021, we estimated that any seroprevalence remained less than 5%, increasing with vaccine rollout to 56% by May–June 2021, 83% by September–October 2021 and 95% by March 2022. Infection-induced seroprevalence remained less than 15% through September–October 2021, increasing across Omicron waves to 42% by March 2022 and 61% by July–August 2022. By August 2022, 70%–80% of children younger than 20 years and 60%–70% of adults aged 20–59 years had been infected, but fewer than half of adults aged 60 years and older had been infected. Compared with estimates of infection-induced seroprevalence, surveillance case reports underestimated infections 12-fold between September 2021 and March 2022 and 92-fold between March 2022 and August 2022. Interpretation: By August 2022, most children and adults younger than 60 years had evidence of both SARS-CoV-2 vaccination and infection. As previous evidence suggests that a history of both exposures may induce stronger, more durable hybrid immunity than either exposure alone, older adults — who have the lowest infection rates but highest risk of severe outcomes — continue to warrant prioritized vaccination. [ABSTRACT FROM AUTHOR]

Background One- and two-dose mRNA vaccine effectiveness (VE) estimates against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by dosing interval and time since vaccination were assessed among healthcare workers (HCWs) in publicly funded acute and community (nonresidential) healthcare facilities in British Columbia, Canada. Methods A test-negative design was used with controls matched to cases (6:1) on epidemiological week of SARS-CoV-2 test date. mRNA vaccination was defined by receipt of the first dose ≥21 days or second dose ≥14 days before the test date. HCWs ≥18 years old tested for SARS-CoV-2 between epi-weeks 3 and 39 (January 17–October 2, 2021) were included, when varying dosing intervals and a mix of circulating variants of concern contributed, including Delta dominance provincially from epi-week 31 (August 1). Results Single- and two-dose analyses included 1265 and 1246 cases, respectively. The median follow-up period (interquartile range) was 49 (34–69) days for single-dose and 89 (61–123) days for two-dose recipients, with 12%, 31%, and 58% of second doses given 3–5, 6, or ≥7 weeks after the first. Adjusted mRNA VE against SARS-CoV-2 was 71% (95% CI, 66%–76%) for one dose and 90% (95% CI, 88%–92%) for two doses, similar to two heterologous mRNA doses (92%; 95% CI, 86%–95%). Two-dose VE remained >80% at ≥28 weeks post–second dose. Two-dose VE was consistently 5%–7% higher with a ≥7-week vs 3–5-week interval between doses, but with overlapping confidence intervals. Conclusions Among HCWs, we report substantial single-dose and strong and sustained two-dose mRNA vaccine protection, with the latter maintained for at least 7 months. These findings support a longer interval between doses, with global health and equity implications. [ABSTRACT FROM AUTHOR]

Background Randomized-controlled trials of messenger RNA (mRNA) vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) included relatively few elderly participants. We assess single-dose mRNA vaccine effectiveness (VE) in adults ≥ 70 years old in British Columbia, Canada, where second doses were deferred by up to 16 weeks and where a spring 2021 wave uniquely included codominant circulation of Alpha (B.1.1.7) and Gamma (P.1) variants of concern (VOC). Methods Analyses included community-dwelling adults ≥ 70 years old with specimen collection between 4 April (epidemiological week 14) and 1 May (week 17) 2021. Adjusted VE was estimated by test-negative design. Cases were reverse-transcription polymerase chain reaction (RT-PCR) test-positive for SARS-CoV-2, and controls were test-negative. Vaccine status was defined by receipt of a single-dose ≥ 21 days before specimen collection, but a range of intervals was assessed. Variant-specific VE was estimated against viruses genetically characterized as Alpha, Gamma or non-VOC lineages. Results VE analyses included 16 993 specimens: 1226 (7%) test-positive cases and 15 767 test-negative controls. Of 1131 (92%) genetically characterized viruses, 509 (45%), 314 (28%), and 276 (24%) were Alpha, Gamma, and non-VOC lineages, respectively. At 0–13 days postvaccination, VE was negligible at 14% (95% confidence interval [CI], 0–26) but increased from 43% (95% CI, 30–53) at 14–20 days to 75% (95% CI, 63–83) at 35–41 days postvaccination. VE at ≥ 21 days postvaccination was 65% (95% CI, 58–71) overall: 72% (95% CI, 58–81), 67% (95% CI, 57–75), and 61% (95% CI, 45–72) for non-VOC, Alpha, and Gamma variants, respectively. Conclusions A single dose of mRNA vaccine reduced the risk of SARS-CoV-2 by about two-thirds in adults ≥ 70 years old, with protection only minimally reduced against Alpha and Gamma variants. [ABSTRACT FROM AUTHOR]

Several severe acute respiratory syndrome coronavirus 2 variants of concern (VoCs) emerged in late 2020; lineage B.1.1.7 initially dominated globally. However, lineages B.1.351 and P.1 represent potentially greater risk for transmission and immune escape. In British Columbia, Canada, B.1.1.7 and B.1.351 were first identified in December 2020 and P.1 in February 2021. We combined quantitative PCR and whole-genome sequencing to assess relative contribution of VoCs in nearly 67,000 infections during the first 16 weeks of 2021 in British Columbia. B.1.1.7 accounted for <10% of screened or sequenced specimens early on, increasing to >50% by week 8. P.1 accounted for <10% until week 10, increased rapidly to peak at week 12, and by week 13 codominated within 10% of rates of B.1.1.7. B.1.351 was a minority throughout. This rapid expansion of P.1 but suppression of B.1.351 expands our understanding of population-level VoC patterns and might provide clues to fitness determinants for emerging VoCs. [ABSTRACT FROM AUTHOR]

Lyme disease, caused by Borrelia burgdorferi sensu lato (s.l.) complex, is the most common vector-borne disease in North America. This disease has a much lower incidence in western compared with eastern North America. Passive tick surveillance data submitted over 17 years from 2002 to 2018 were analyzed to determine the occurrence of tick species and the prevalence of Borrelia spp. in ticks in British Columbia (BC), Canada. The BC Centre for Disease Control Public Health Laboratory received tick submissions from physicians, veterinarians, and BC residents. Ticks were identified to species, and all ticks, except Dermacentor andersoni, were tested using generic B. burgdorferi s.l. primer sets and species-specific PCR primer sets for B. burgdorferi sensu stricto (s.s.). Tick submission data were analyzed to assess temporal and geographical trends, tick life stages, and tick species. Poisson regression was used to assess temporal trends in annual tick submissions. A total of 15,464 ticks were submitted. Among these, 0.29% (n = 10,235) of Ixodes spp. ticks and 5.3% (n = 434) of Rhipicephalus sanguineus ticks were found carrying B. burgdorferi s.s. B. burgdorferi s.s. was primarily detected in Ixodes pacificus (52%; n = 16) and Ixodes angustus ticks (19%; n = 6) retrieved from humans (n = 5) and animals (n = 26). B. burgdorferi was found in ticks submitted throughout the year. Ixodes spp. ticks were primarily submitted from the coastal regions of southwestern BC, and D. andersoni ticks were primarily submitted from southern interior BC. The number of human tick submissions increased significantly (p < 0.001) between 2013 and 2018. The annual prevalence of B. burgdorferi in ticks remained stable during the study period. These findings correspond to those observed in US Pacific Northwestern states. Passive tick surveillance is an efficient tool to monitor long-term trends in tick distribution and B. burgdorferi prevalence in a low endemicity region. [ABSTRACT FROM AUTHOR]

First Nations Peoples in the province of British Columbia (BC), Canada, have been disproportionately affected by the overdose crisis. In 2016, a public health emergency was declared by BC's Provincial Health Officer (PHO) in response to the significant rise in opioid-related overdose deaths reported in BC. New surveillance systems were required to identify trends in overdose events and related deaths in the province as a whole, and for First Nations Peoples. Data sharing and analysis processes that adhered to the principles of OCAP® (ownership, control, access, and possession), and to the Truth and Reconciliation Commission of Canada's Calls to Action, needed to be developed. The First Nations Health Authority (FNHA), BC Centre for Disease Control, PHO, and the BC Ministry of Health have worked collaboratively to facilitate identification of First Nations persons in surveillance data for appropriate analysis by FNHA. This paper outlines the data stewardship and governance context, principles, and operational considerations for creating overdose surveillance systems to measure overdose events among First Nations Peoples in BC. [ABSTRACT FROM AUTHOR]

Connection to land has been identified as a central determinant of the health and well-being of First Nations in Canada. The wholistic, interconnected, spiritual, and sacred relationship that many Indigenous Peoples have with the land is an integral part of strengthening physical, spiritual, mental, and emotional health and well-being. However, there has been little empirical evidence on how to assess, measure, and report on connection to land for First Nations Peoples. Using a Two-Eyed Seeing approach, this study explores what connection to land, water, and territory means for health and wellness for First Nations in the Fraser Salish region in the province of British Columbia (BC), Canada. Data were collected through a sharing circle with five First Nations Knowledge Keepers and five youth from Stó:lō communities as part of a land-based gathering in Stó:lō territory. Three themes were identified: (a) "the spirits of the land, water, and territory are within us": the intersection of cultural identity, spirituality, ancestral knowledge, and health and well-being; (b) letsemot, "togetherness": relationality; and (c) disruptions and new ways of living. For Stó:lō Peoples, connection to the land is an integral component of health and well-being. Connection to land was found to strongly influence physical, spiritual, mental, and emotional aspects of health while also intersecting with Stó:lō cultural identity, spirituality, ancestral knowledge, and ways of living. The findings can be used to inform the development of an indicator for connection to land, water, and territory as a measurement of ecological wellness for the First Nations Population Health and Wellness Agenda in BC. [ABSTRACT FROM AUTHOR]

Background and aims: The province of British Columbia (BC) Canada has experienced a rapid increase in illicit drug overdoses and deaths during the last 4 years, with a provincial emergency declared in April 2016. These deaths have been driven primarily by the introduction of synthetic opioids into the illicit opioid supply. This study aimed to measure the combined impact of large‐scale opioid overdose interventions implemented in BC between April 2016 and December 2017 on the number of deaths averted. Design We expanded on the mathematical modelling methodology of our previous study to construct a Bayesian hierarchical latent Markov process model to estimate monthly overdose and overdose‐death risk, along with the impact of interventions. Setting and Cases: Overdose events and overdose‐related deaths in BC from January 2012 to December 2017. Interventions: The interventions considered were take‐home naloxone kits, overdose prevention/supervised consumption sites and opioid agonist therapy Measurements Counterfactual simulations were performed with the fitted model to estimate the number of death events averted for each intervention and in combination. Findings Between April 2016 and December 2017, BC observed 2177 overdose deaths (77% fentanyl‐detected). During the same period, an estimated 3030 (2900–3240) death events were averted by all interventions combined. In isolation, 1580 (1480–1740) were averted by take‐home naloxone, 230 (160–350) by overdose prevention services and 590 (510–720) were averted by opioid agonist therapy. Conclusions: A combined intervention approach has been effective in averting overdose deaths during British Columbia's opioid overdose crisis in the period since declaration of a public health emergency (April 2016–December 2017). However, the absolute numbers of overdose deaths have not changed. [ABSTRACT FROM AUTHOR]

Background: Late HIV diagnosis is associated with increased AIDS-related morbidity and mortality as well as an increased risk of HIV transmission. In this study, we quantified and characterized missed opportunities for earlier HIV diagnosis in British Columbia (BC), Canada. Design: Retrospective cohort. Methods: A missed opportunity was defined as a healthcare encounter due to a clinical manifestation which may be caused by HIV infection, or is frequently present among those with HIV infection, but no HIV diagnosis followed within 30 days. We developed an algorithm to identify missed opportunities within one, three, and five years prior to diagnosis. The algorithm was applied to the BC STOP HIV/AIDS population-based cohort. Eligible individuals were ≥18 years old, and diagnosed from 2001–2014. Multivariable logistic regression identified factors associated with missed opportunities. Results: Of 2119 individuals, 7%, 12% and 14% had ≥1 missed opportunity during one, three and five years prior to HIV diagnosis, respectively. In all analyses, individuals aged ≥40 years, heterosexuals or people who ever injected drugs, and those residing in Northern health authority had increased odds of experiencing ≥1 missed opportunity. In the three and five-year analysis, individuals with a CD4 count <350 cells/mm3 were at higher odds of experiencing ≥1 missed opportunity. Prominent missed opportunities were related to recurrent pneumonia, herpes zoster/shingles among younger individuals, and anemia related to nutritional deficiencies or unspecified cause. Conclusions: Based on our newly-developed algorithm, this study demonstrated that HIV-diagnosed individuals in BC have experienced several missed opportunities for earlier diagnosis. Specific clinical indicator conditions and population sub-groups at increased risk of experiencing these missed opportunities were identified. Further work is required in order to validate the utility of this proposed algorithm by establishing the sensitivity, specificity, positive and negative predictive values corresponding to the incidence of the clinical indicator conditions among both HIV-diagnosed and HIV-negative populations. [ABSTRACT FROM AUTHOR]

We quantified the contributions of leading causes of death and drug overdose to changes in life expectancy at birth over time and inequalities by sex and socioeconomic status in British Columbia. From 2014 to 2016, life expectancy at birth declined by 0.38 years and drug overdose deaths (mainly opioid-involved) contributed a loss of 0.12 years of the decrease. The analysis also demonstrated that the higher drug overdose mortality among males and among those in lower socioeconomic status communities contributed to a differential decrease in life expectancy at birth for males and for those in the latter category. [ABSTRACT FROM AUTHOR]

To determine the prevalence of Borrelia burgdorferi in British Columbian ticks, fieldwork was conducted over a 2-year period. In all, 893 ticks ( Ixodes pacificus, I. angustus, I. soricis, Ixodes spp., and Dermacentor andersoni) of different life stages were retrieved from 483 small rodents ( Peromyscus maniculatus, Perognathus parvus, and Reithrodontomys megalotis). B. burgdorferi DNA was detected in 5 out of 359 tick pools, and 41 out of 483 mice were serologically confirmed to have antibodies against B. burgdorferi. These results were consistent with previous studies, data from passive surveillance in British Columbia, and data from neighboring states in the Pacific Northwest, suggesting a continually low prevalence of B. burgdorferi in British Columbia ticks. [ABSTRACT FROM AUTHOR]

In 2009, an expansion of West Nile virus (WNV) into the Canadian province of British Columbia was detected. Two locally acquired cases of infection in humans and cases of infection in horses were detected by ELISA and plaque-reduction neutralization tests. Ten positive mosquito pools were detected by reverse transcription-PCR. Most WNV activity in British Columbia in 2009 occurred in the hot and dry southern Okanagan Valley. Virus establishment and amplification in this region was likely facilitated by above average nightly temperatures and a rapid accumulation of degree-days in late summer. Estimated exposure dates for humans and initial detection of WNV-positive mosquitoes occurred concurrently with a late summer increase in Culex tarsalis mosquitoes (which spread western equine encephalitis) in the southern Okanagan Valley. The conditions present during this range expansion suggest that temperature and Cx. tarsalis mosquito abundance may be limiting factors for WNV transmission in this portion of the Pacific Northwest. [ABSTRACT FROM AUTHOR]

The article looks at the results of the survey conducted by the British Columbia Centre for Disease Control (BCCDC) among physicians on their knowledge, beliefs and practices around Lyme disease (LD). According to the survey, 28% of respondents had treated at least one case of LD. It cites erythema migrans as the most common patient-reported system and physician-observed sign. It also found that majority of physicians suspected LD when they observed erythema migrans in patients.

Objectives In 2012, British Columbia (BC) became the first Canadian province to implement an influenza prevention policy requiring healthcare workers (HCW) to either be vaccinated annually against influenza or wear a mask in patient care areas during the influenza season. This study describes an evaluation of influenza policy implementation processes and identifies supports and challenges related to successful policy implementation at the level of healthcare facilities, during the second policy year (2013/14). Methods Implementation leaders from 262 long-term care (LTC) and acute care facilities, mostly in three of BC’s five regional Health Authorities, were invited to participate in an online survey following the 2013/14 influenza season. Descriptive quantitative and qualitative analyses identified common and effective strategies for improving vaccination coverage and policy compliance. Results A total of 127 respondents completed the survey on behalf of 33 acute care and 99 LTC facilities, representing 36% of acute care and 27% of LTC facilities in BC. Respondents agreed that the policy was successfully implemented at 89% of facilities, and implementation was reported to be easy at 52% of facilities. The findings elaborate on communication and leadership strategies, campaign logistics and enforcement approaches involved in policy implementation. Conclusion Implementation of a vaccinate-or-mask influenza policy is complex. This study provides insight for other jurisdictions considering implementing such a policy and offers practical recommendations for facilities and health authorities. [ABSTRACT FROM AUTHOR]

Objectives: Drug checking is a harm reduction intervention that allows for identification of drug composition. The objective of the study was to assess drug market components and concordance between expected substance reported by clients and results from point-of-care drug checking at music festivals and events in British Columbia.Methods: From July to September 2018, we provided drug checking services at four events using combination Fourier Transform Infrared (FTIR) spectroscopy and fentanyl immunoassay strips. We measured concordance between expected substance as reported by clients to the results from the FTIR/fentanyl immunoassay strip and tracked unexpected adulterants.Results: In total, 336 checks were completed. Most samples were expected by clients to be psychedelics (69.3%) or stimulants (19.6%). Of the 233 psychedelic samples, 169 (72.5%) contained the expected, unadulterated substance, and 27 (11.6%) contained additional contaminants. Of 66 stimulant samples, 41 (62.1%) contained expected substance, while 24 (36.4%) contained additional contaminants. Unexpected adulterants such as fentanyl, levamisole, and phenacetin were also found, in addition to several novel psychoactive substances.Discussion: We found a large proportion of substances that contained unexpected adulterants. Our findings highlight the value of continued drug checking and will be helpful in designing future harm reduction interventions in similar contexts. [ABSTRACT FROM AUTHOR]

Background: Population-based cross-sectional serosurveys within the Lower Mainland, British Columbia, Canada, showed about 10%, 40% and 60% of residents were infected with SARS-CoV-2 by the sixth (September 2021), seventh (March 2022) and eighth (July 2022) serosurveys. We conducted the ninth (December 2022) and tenth (July 2023) serosurveys and sought to assess risk of severe outcomes from a first-ever SARS-CoV-2 infection during intersurvey periods., Methods: Using increments in cumulative infection-induced seroprevalence, population census, discharge abstract and vital statistics data sets, we estimated infection hospitalization and fatality ratios (IHRs and IFRs) by age and sex for the sixth to seventh (Delta/Omicron-BA.1), seventh to eighth (Omicron-BA.2/BA.5) and eighth to ninth (Omicron-BA.5/BQ.1) intersurvey periods. As derived, IHR and IFR estimates represent the risk of severe outcome from a first-ever SARS-CoV-2 infection acquired during the specified intersurvey period., Results: The cumulative infection-induced seroprevalence was 74% by December 2022 and 79% by July 2023, exceeding 80% among adults younger than 50 years but remaining less than 60% among those aged 80 years and older. Period-specific IHR and IFR estimates were consistently less than 0.3% and 0.1% overall. By age group, IHR and IFR estimates were less than 1.0% and up to 0.1%, respectively, except among adults aged 70-79 years during the sixth to seventh intersurvey period (IHR 3.3% and IFR 1.0%) and among those aged 80 years and older during all periods (IHR 4.7%, 2.2% and 3.5%; IFR 3.3%, 0.6% and 1.3% during the sixth to seventh, seventh to eighth and eighth to ninth periods, respectively). The risk of severe outcome followed a J-shaped age pattern. During the eighth to ninth period, we estimated about 1 hospital admission for COVID-19 per 300 newly infected children younger than 5 years versus about 1 per 30 newly infected adults aged 80 years and older, with no deaths from COVID-19 among children but about 1 death per 80 newly infected adults aged 80 years and older during that period., Interpretation: By July 2023, we estimated about 80% of residents in the Lower Mainland, BC, had been infected with SARS-CoV-2 overall, with low risk of hospital admission or death; about 40% of the oldest adults, however, remained uninfected and at highest risk of a severe outcome. First infections among older adults may still contribute substantial burden from COVID-19, reinforcing the need to continue to prioritize this age group for vaccination and to consider them in health care system planning., Competing Interests: Competing interests: Danuta Skowronski reports grants from the Canadian Institutes of Health Research and the BCCDC Foundation for Public Health, paid to her institution, for other SARS-CoV-2 work. Romina Reyes is chair of the British Columbia Diagnostic Accreditation Program committee. As the Provincial Health Officer with authority under the emergency provisions of the Public Health Act, Bonnie Henry authorized the provision and analysis of the anonymized sera used in this study; the study was separately reviewed and approved by the University of British Columbia Clinical Research Ethics Board. No other competing interests were declared., (© 2023 CMA Impact Inc. or its licensors.)

Background: The evolving proportion of the population considered immunologically naive versus primed for more efficient immune memory response to SARS-CoV-2 has implications for risk assessment. We sought to chronicle vaccine- and infection-induced seroprevalence across the first 7 waves of the COVID-19 pandemic in British Columbia, Canada., Methods: During 8 cross-sectional serosurveys conducted between March 2020 and August 2022, we obtained anonymized residual sera from children and adults who attended an outpatient laboratory network in the Lower Mainland (Greater Vancouver and Fraser Valley). We used at least 3 immunoassays per serosurvey to detect SARS-CoV-2 spike and nucleocapsid antibodies. We assessed any seroprevalence (vaccineor infection-induced, or both), defined by positivity on any 2 assays, and infection-induced seroprevalence, also defined by dual-assay positivity but requiring both antinucleocapsid and antispike detection. We used estimates of infection-induced seroprevalence to explore underascertainment of infections by surveillance case reports., Results: By January 2021, we estimated that any seroprevalence remained less than 5%, increasing with vaccine rollout to 56% by May-June 2021, 83% by September-October 2021 and 95% by March 2022. Infection-induced seroprevalence remained less than 15% through September-October 2021, increasing across Omicron waves to 42% by March 2022 and 61% by July-August 2022. By August 2022, 70%-80% of children younger than 20 years and 60%-70% of adults aged 20-59 years had been infected, but fewer than half of adults aged 60 years and older had been infected. Compared with estimates of infection-induced seroprevalence, surveillance case reports underestimated infections 12-fold between September 2021 and March 2022 and 92-fold between March 2022 and August 2022., Interpretation: By August 2022, most children and adults younger than 60 years had evidence of both SARS-CoV-2 vaccination and infection. As previous evidence suggests that a history of both exposures may induce stronger, more durable hybrid immunity than either exposure alone, older adults - who have the lowest infection rates but highest risk of severe outcomes - continue to warrant prioritized vaccination., Competing Interests: Competing interests: Danuta Skowronski reports grants from the Canadian Institutes of Health Research and the British Columbia Centre for Disease Control Foundation for Public Health, paid to her institution, for other SARS-CoV-2 work. Romina Reyes is chair of the BC Diagnostic Accreditation Program committee. Mel Krajden reports grants paid to his institution from Roche, Hologic and Siemens. No other competing interests were declared., (© 2022 CMA Impact Inc. or its licensors.)

Background: The Canadian coronavirus disease 2019 (COVID-19) immunization strategy deferred second doses and allowed mixed schedules. We compared 2-dose vaccine effectiveness (VE) by vaccine type (mRNA and/or ChAdOx1), interval between doses, and time since second dose in 2 of Canada's larger provinces., Methods: Two-dose VE against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or hospitalization among adults ≥18 years, including due to Alpha, Gamma, and Delta variants of concern (VOCs), was assessed ≥14 days postvaccination by test-negative design studies separately conducted in British Columbia and Quebec, Canada, between 30 May and 27 November (epi-weeks 22-47) 2021., Results: In both provinces, all homologous or heterologous mRNA and/or ChAdOx1 2-dose schedules were associated with ≥90% reduction in SARS-CoV-2 hospitalization risk for ≥7 months. With slight decline from a peak of >90%, VE against infection was ≥80% for ≥6 months following homologous mRNA vaccination, lower by ∼10% when both doses were ChAdOx1 but comparably high following heterologous ChAdOx1 + mRNA receipt. Findings were similar by age group, sex, and VOC. VE was significantly higher with longer 7-8-week versus manufacturer-specified 3-4-week intervals between mRNA doses., Conclusions: Two doses of any mRNA and/or ChAdOx1 combination gave substantial and sustained protection against SARS-CoV-2 hospitalization, spanning Delta-dominant circulation. ChAdOx1 VE against infection was improved by heterologous mRNA series completion. A 7-8-week interval between first and second doses improved mRNA VE and may be the optimal schedule outside periods of intense epidemic surge. Findings support interchangeability and extended intervals between SARS-CoV-2 vaccine doses, with potential global implications for low-coverage areas and, going forward, for children., Competing Interests: Potential conflicts of interest. G. D. S. received a grant paid to his institution for a meningococcal seroprevalence study from Pfizer in 2016. M. K. received grants/contracts paid to his institution from Roche (related to human papillomavirus), Hologic (related to human papillomavirus), and Siemens (related to human papillomavirus), unrelated to this work. M. S. has been an investigator on projects, unrelated to the current work, funded by GlaxoSmithKline, Merck, Moderna, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo, and VBI Vaccines. All funds have been paid to his institute, and he has not received any personal payments. M. S. is also the Chair/Deputy Chair of 2 Data Safety Monitoring Boards (DSMBs) for coronavirus disease 2019 (COVID-19) vaccine trials, involving different vaccines. R. G. received honoraria for an RSV Coordinators Workshop funded by AbbVie (payment to author). A. N. J. has received funding for other severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing and COVID-19 vaccine projects, paid to her institution and unrelated to the current work, from Genome BC, the Public Health Agency of Canada and the Canada Foundation for Innovation. D. M. S. reports contracts or grants, paid to her institution and unrelated to the current work, from Michael Smith Foundation for Health Research, Public Health Agency of Canada, and the Canadian Institutes of Health Research. G. D. reports a grant or contract paid to his institution from the Ministère de la Santé et des Services Sociaux du Québec. E. G. reports that their spouse is employed by QHR Tech, an electronic medical records company (no payments to author and author owns no stock in the company). All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.)

Background: In British Columbia, Canada, most adults 50-69 years old became eligible for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in April 2021, with chimpanzee adenoviral vectored vaccine (ChAdOx1) restricted to ≥55-year-olds and second doses deferred ≥6 weeks to optimize single-dose coverage., Methods: Among adults 50-69 years old, single-dose messenger RNA (mRNA) and ChAdOx1 vaccine effectiveness (VE) against SARS-CoV-2 infection and hospitalization, including variant-specific, was assessed by test-negative design between 4 April and 2 October 2021., Results: Single-dose VE included 11 861 cases and 99 544 controls. Median of postvaccination follow-up was 32 days (interquartile range, 15-52 days). Alpha, Gamma, and Delta variants comprised 23%, 18%, and 56%, respectively, of genetically characterized viruses. At 21-55 days postvaccination, single-dose mRNA and ChAdOx1 VE (95% confidence interval [CI]) was 74% (71%-76%) and 59% (53%-65%) against any infection and 86% (80%-90%) and 94% (85%-97%) against hospitalization, respectively. VE (95% CI) was similar against Alpha and Gamma infections for mRNA (80% [76%-84%] and 80% [75%-84%], respectively) and ChAdOx1 (69% [60%-76%] and 66% [56%-73%], respectively). mRNA VE was lower at 63% (95% CI, 56%-69%) against Delta but 85% (95% CI, 71%-92%) against Delta-associated hospitalization (nonestimable for ChAdOx1)., Conclusions: A single mRNA or ChAdOx1 vaccine dose gave important protection against SARS-CoV-2, including early variants of concern. ChAdOx1 VE was lower against infection, but 1 dose of either vaccine reduced the hospitalization risk by >85% to at least 8 weeks postvaccination. Findings inform program options, including longer dosing intervals., Competing Interests: Potential conflicts of interest. D. M. S. is Principal or Co-Investigator on grants from the Michael Smith Foundation for Health Research, the Public Health Agency of Canada, and the Canadian Institutes of Health Research paid to her institution and unrelated to the current work. M. K. received grants/contracts paid to his institution from Roche, Hologic, and Siemens, unrelated to this work. M. S. has been an investigator on projects, unrelated to the current work, funded by GlaxoSmithKline, Merck, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo, and VBI Vaccines; all funds have been paid to his institute, and he has not received any personal payments. All other authors report no potential conflicts of interest., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America.)

Setting: Congenital anomalies (CAs) can cause lifelong morbidity and accounted for 23.2% of infant deaths from 2003 to 2007. In British Columbia (BC), surveillance of CAs has been irregular since the early 2000s. To enhance CAs surveillance in BC, the Public Health Agency of Canada has provided funding for the implementation of the BC Congenital Anomalies Surveillance System (BCCASS)., Intervention: BCCASS is a population-based surveillance system. The system leverages existing administrative data sources that capture information regarding vital events, disease status, drug prescription, and healthcare utilization. The system uses a series of algorithms to capture specific CAs diagnoses, some of which are further validated with the support of the Provincial Advisory Committee. This Advisory Committee is a multi-stakeholder coalition that includes the BC Office of the Provincial Health Officer, subject matter experts, data partners, users, and academia, and acts to provide support, expertise, and strategic guidance to BCCASS., Outcomes: Through BCCASS, prevalence and historical trends for 35 CAs in BC are available. Information pertaining to maternal place of residence, risk, and protective factors can be used for association studies such as links to environmental hazards and cluster analysis., Implications: BCCASS is a cost-effective and sustainable system that leverages existing data sources necessary to understand the overall burden of CAs across the BC population. This is fundamental to support data-driven decisions around policy development, program planning, and evaluation of preventive measures. Strong coalitions with stakeholders are instrumental to ensure successful implementation and expansion in the future., (© 2022. The Author(s) under exclusive license to The Canadian Public Health Association.)

Background: Despite the long-standing experience of rating the evidence for clinical preventive services, the delivery of effective clinical preventive services in Canada and elsewhere is less than optimal. We outline an approach used in British Columbia to assist in determining which effective clinical preventive services are worth doing., Methods: We calculated the clinically preventable burden and cost-effectiveness for 28 clinical preventive services that received a 'strong or conditional (weak) recommendation for' by the Canadian Task Force on Preventive Health Care or an 'A' or 'B' rating by the United States Preventive Services Task Force. Clinically preventable burden is the total quality adjusted life years that could be gained if the clinical preventive services were delivered at recommended intervals to a British Columbia birth cohort of 40,000 individuals over the years of life that the service is recommended. Cost-effectiveness is the net cost per quality adjusted life year gained., Results: Clinical preventive services with the highest population impact and best value for money include services that address tobacco use in adolescents and adults, exclusive breastfeeding, and screening for hypertension and other cardiovascular disease risk factors followed by appropriate pharmaceutical treatment. In addition, alcohol misuse screening and brief counseling, one-time screening for hepatitis C virus infection in British Columbia adults born between 1945 and 1965, and screening for type 2 diabetes approach these high-value clinical preventive services., Conclusions: These results enable policy makers to say with some confidence what preventive manoeuvres are worth doing but further work is required to determine the best way to deliver these services to all those eligible and to establish what supportive services are required. After all, if a clinical preventive service is worth doing, it is worth doing well., (© 2022. The Author(s).)

Lyme disease, caused by Borrelia burgdorferi sensu lato (s.l.) complex, is the most common vector-borne disease in North America. This disease has a much lower incidence in western compared with eastern North America. Passive tick surveillance data submitted over 17 years from 2002 to 2018 were analyzed to determine the occurrence of tick species and the prevalence of Borrelia spp. in ticks in British Columbia (BC), Canada. The BC Centre for Disease Control Public Health Laboratory received tick submissions from physicians, veterinarians, and BC residents. Ticks were identified to species, and all ticks, except Dermacentor andersoni , were tested using generic B. burgdorferi s.l. primer sets and species-specific PCR primer sets for B. burgdorferi sensu stricto (s.s.). Tick submission data were analyzed to assess temporal and geographical trends, tick life stages, and tick species. Poisson regression was used to assess temporal trends in annual tick submissions. A total of 15,464 ticks were submitted. Among these, 0.29% ( n  = 10,235) of Ixodes spp. ticks and 5.3% ( n  = 434) of Rhipicephalus sanguineus ticks were found carrying B. burgdorferi s.s. B. burgdorferi s.s. was primarily detected in Ixodes pacificus (52%; n  = 16) and Ixodes angustus ticks (19%; n  = 6) retrieved from humans ( n  = 5) and animals ( n  = 26). B. burgdorferi was found in ticks submitted throughout the year. Ixodes spp. ticks were primarily submitted from the coastal regions of southwestern BC, and D. andersoni ticks were primarily submitted from southern interior BC. The number of human tick submissions increased significantly ( p  < 0.001) between 2013 and 2018. The annual prevalence of B. burgdorferi in ticks remained stable during the study period. These findings correspond to those observed in US Pacific Northwestern states. Passive tick surveillance is an efficient tool to monitor long-term trends in tick distribution and B. burgdorferi prevalence in a low endemicity region.

Influenza can be potentially fatal to vulnerable populations, particularly those in the hospital. Canada's National Advisory Committee on Immunization recommends that health-care workers (HCW) be immunized against influenza partly to avoid infecting high-risk populations. However, influenza immunization rates among HCW remain suboptimal. In 2012, health authorities across British Columbia (B.C.) implemented a province-wide influenza prevention policy requiring HCW to either be immunized or wear a mask when in patient-care areas during the influenza season. This paper describes the second of two studies focused on what was learned from years 2 and 3 of the policy. A case study approach was used to examine this policy implementation event. Qualitative data were collected through key documents and key informant interviews with members of leadership teams responsible for policy implementation. Framework analysis and Prior's approach were used to analyze data from interviews and documents, respectively. Policy implementation varied by geographic region and gaps persist in immunization tracking and discipline for noncompliance. Debate regarding the scientific evidence used to support the policy fuels resistance from particular groups. Despite these challenges, findings suggest that the policy has been habituated, largely due to consistent policy objectives. This study emphasizes the importance of ongoing inter-professional and cross-sectoral program evaluation. While adherence may be routine for many, implementation processes must continue to respond to contextual issues to narrow the gap in policy implementation and to continue to engage stakeholders to ensure compliance.

Purpose of Review: This study proposes to describe the impact of a publicly funded Treatment as Prevention (TasP) strategy in British Columbia (BC), Canada, in decreasing the individual and public health impact of the HIV/AIDS Epidemic., Recent Findings: In BC, TasP has been associated with a steady decline in HIV-related morbidity and mortality. At the same time, a demographic transition was observed among people living with HIV (PLWH), with the majority of those on antiretroviral treatment (ART) now ≥ 50 years of age, living with at least one comorbidity, and dying from age-associated comorbidities. We also documented a progressive increase in the proportion of viral load suppression as a result of ART expansion. While the pre-ART CD4 T cell count has increased steadily in recent years, there is still a large proportion of PLWH being diagnosed in later stages of HIV infection. New HIV diagnoses have been rapidly declining, however to a lesser extent among men who have sex with men (MSM), and BC is currently experiencing an increase in infectious syphilis cases in this population. These facts reinforce the effectiveness of TasP in decreasing HIV transmission, but at the same time, it highlights the need for further innovation to enhance the control of HIV and syphilis among MSM. This study supports the development of new approaches that address existing gaps in the TasP strategy in BC, and the future health needs of PLWH.

Objectives: Vaccinate-or-mask (VOM) policies aim to improve influenza vaccine coverage among healthcare workers (HCW) and reduce influenza-related illness among patients and staff. In 2012, British Columbia (BC) implemented a province-wide VOM influenza prevention policy. This study describes an evaluation of policy impacts on HCW absenteeism rates from before to after policy implementation., Methods: Using payroll data from regional and provincial Health Authorities (HA), we assessed all-cause sick rates (sick time as a proportion of sick time and productive time) before (2007-2011, excluding 2009-2010) and after (2012-2017) policy implementation, and during influenza season (December 1-March 31) and non-influenza season (April 1-November 30). We used a two-part negative binomial hurdle model to calculate odds ratios (OR) of taking any sick time, relative rates (RR) of sick time taken, and predicted mean sick rates, adjusting for age group, sex, job type, job classification, HA, year and vaccine effectiveness., Results: During influenza season, HCWs in the post-policy period were less likely to take any sick time (OR 0.989, 95%CI: 0.979-0.999) but had higher rates of sick time (RR 1.038, 95%CI: 1.030-1.045). However, during non-influenza season, HCWs in the post-policy period were more likely to take any sick time (OR 1.015, 95%CI: 1.008-1.022) but had lower rates of sick time (RR 0.971, 95%CI: 0.966-0.976). There was an overall increase in predicted mean sick rate from pre to post-policy in influenza season (4.392% to 4.508%) and non-influenza season (3.815% to 3.901%)., Conclusions: The observed year-round increase in sick rates from pre-to-post policy was likely influenced by other factors; however, opposite trends in how HCWs took sick time in the influenza and non-influenza seasons may reflect policy influences and need further research to explore reasons for these differences., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

We quantified the contributions of leading causes of death and drug overdose to changes in life expectancy at birth over time and inequalities by sex and socioeconomic status in British Columbia. From 2014 to 2016, life expectancy at birth declined by 0.38 years and drug overdose deaths (mainly opioid-involved) contributed a loss of 0.12 years of the decrease. The analysis also demonstrated that the higher drug overdose mortality among males and among those in lower socioeconomic status communities contributed to a differential decrease in life expectancy at birth for males and for those in the latter category., Competing Interests: The authors have no conflicts of interest to disclose.

In August 2012, British Columbia became the first Canadian province to implement a province-wide Influenza Prevention Policy requiring all healthcare workers (HCWs) in residential and acute care facilities to either be immunized against influenza, or wear masks in patient care areas during the influenza season. This qualitative case study sought to understand the key facilitators and barriers involved in developing and implementing British Columbia's Influenza Prevention Policy. An explanatory qualitative case study approach was selected for this project. Data were collected through the review of 110 documents (policy and planning documents, implementation tools, press releases, communication materials, etc.), and through 7 focus groups with policy implementation team members (n = 48). Focus group interview transcripts were analyzed using Framework Analysis methods, and Prior's approach guided document analysis. Four themes were identified: (1) Clashing paradigms, (2) Policy implementation gaps, (3) Pathways of power, and (4) Personal impacts. Issues embedded in macro-, meso-, and micro-level contexts, and planning across the province, were identified as critical to policy implementation. A province-wide approach with senior-level engagement and dedicated resources is critical in a province-wide influenza prevention policy for HCW. Recommendations to improve large-scale implementation of condition-of-service influenza policies include: engaging stakeholders early, considering the complexity of political contexts, allotting time to plan appropriately, developing 'enforcement' plans, and providing education and skills to frontline providers.

To determine the prevalence of Borrelia burgdorferi in British Columbian ticks, fieldwork was conducted over a 2-year period. In all, 893 ticks (Ixodes pacificus, I. angustus, I. soricis, Ixodes spp., and Dermacentor andersoni) of different life stages were retrieved from 483 small rodents (Peromyscus maniculatus, Perognathus parvus, and Reithrodontomys megalotis). B. burgdorferi DNA was detected in 5 out of 359 tick pools, and 41 out of 483 mice were serologically confirmed to have antibodies against B. burgdorferi. These results were consistent with previous studies, data from passive surveillance in British Columbia, and data from neighboring states in the Pacific Northwest, suggesting a continually low prevalence of B. burgdorferi in British Columbia ticks.

Objectives: In British Columbia (BC), Canada, neuraminidase inhibitors (NIs) were publicly funded during the 2009 A(H1N1)pdm09 pandemic for treatment of high-risk patients and/or anyone with moderate-to-severe illness. We assessed antiviral effectiveness (AVE) against hospitalization in that context., Methods: A population-based cohort study was conducted using linked administrative data. The cohort included all individuals living in BC during the study period (1 September to 31 December 2009) with a diagnostic code consistent with influenza or pandemic H1N1. The main study period pertained to the second-wave A(H1N1)pdm09 circulation (1 October to 31 December 2009), with sensitivity analyses around the more specific pandemic peak (18 October to 7 November). Exposure was defined by same-day NI prescription. The main outcome was all-cause hospitalization within 14 days of the outpatient influenza diagnosis. Cox proportional hazards models assessed AVE with 1 : 1 propensity-score matching and covariate adjustment., Results: After matching, there were 304/58,061 NI-exposed and 345/58,061 unexposed patients hospitalized during the main study period. The very young [<6 months (35.0; 95% CI 16.7-73.4)], the old [65-79 years (13.7; 95% CI 10.1-18.6)] and the very old [≥80 years (38.7; 95% CI 26.6-56.5)] had the highest hospitalization rate per 1000 patients overall. Fully adjusted AVE against all-cause hospitalization during the main study period was 16% (95% CI 2%-28%), similar to the pandemic peak (15%; 95% CI -4%-30%)., Conclusions: The use of NIs was associated with modest protection against hospitalization during the 2009 pandemic, but appeared underutilized in affected age groups with the highest hospitalization risk.

Objective: To determine physicians' level of awareness and knowledge of Lyme disease (LD) in a low-prevalence area and whether physicians' practices align with current guidelines for treatment of LD., Design: A 23-item questionnaire assessing demographic characteristics, general knowledge about LD, laboratory testing for LD, and responses to 3 clinical scenarios., Setting: British Columbia (BC)., Participants: Pediatricians, FPs, and internal medicine specialists who were licensed to practise in BC., Main Outcome Measures: Knowledge of signs and symptoms of LD, beliefs about risk of LD, attitudes toward LD in patients in their practices, and application of accepted practice guidelines for the treatment of LD in clinical scenarios., Results: Overall, 80.6% of respondents were FPs. Average knowledge score was 72.5% for FPs and 75.0% for other specialists. Most respondents (75.6% of FPs and 71.8% of other specialists) underestimated the occurrence of erythema migrans (EM), and only 26.1% and 28.3%, respectively, knew that EM alone was diagnostic for LD. A total of 30.5% of FPs and 12.1% of other specialists reported having treated a patient for the disease despite not believing that the patient had LD. Of all the respondents, 62.1% knew that LD was a reportable disease in BC. Respondents' reports of risk of LD in their areas were appropriately associated with actual risk based on ecological niche., Conclusion: Physicians are knowledgeable about the clinical signs and symptoms of LD and aware of the risk of the disease despite being in a low-endemic area. Physicians in BC are comfortable with treating patients empirically for LD. Education is needed to inform physicians that EM is diagnostic and no laboratory testing is indicated before treatment. Raising awareness among physicians that LD is reportable might improve reporting of future cases.

Since its first detection in New York (1999), West Nile virus (WNv) has spread across the United States and Canada with the first activity reported in Canada in 2001. By 2004, WNv had been detected almost in every province of Canada and the contiguous regions of the United States with the exception of British Columbia (BC), this despite being detected in Alberta in 2003 and Washington as early as 2002. In August 2009, two human cases were serologically found to have WNv infection. They reported mosquito bites and had only traveled in the South and Central Okanagan areas of BC before their presentation. On the basis of clinical, laboratory, and epidemiological data, these two human cases have been confirmed as the first locally acquired WNv cases in BC. Various factors may have contributed to the 10-year delay in the spread of WNv to BC, including regional weather conditions and unique topography.

Lyme disease (LD) is rare in British Columbia (BC) and, despite being a reportable condition since 1994, may be underreported. Here we review all provincial laboratory and clinical databases to determine the number of LD cases reported in BC from 1997 to 2008. We analyzed demographic characteristics of LD cases and used capture-recapture methodology to estimate the true number of cases in BC for this period. From 1997 to 2008, 93 confirmed cases of LD were reported in BC. Conservative capture-recapture estimates place the true number of LD cases in BC during this period at 142 (95% confidence interval: 111-224), indicating up to 40% underreporting of this rare disease. Despite this underreporting, BC continues to have low endemic risk of LD. Strategies are needed to increase both physician awareness and the use of preventive measures in the BC population, including for those traveling to other endemic areas.

Objective: "Do Bugs Need Drugs" (DBND) is a community education program that was implemented in British Columbia (BC) in September 2005 to decrease inappropriate antibiotic use. This study conducted descriptive analyses of the association between DBND and changes in overall, pediatric, drug-specific, and indication-specific antibiotic utilization rates in Vancouver, BC., Methods: Utilization data on all oral solid and liquid antibiotics classified as "antibacterials for systemic use" were obtained from BC PharmaNet for the years 1996 to 2008. Utilization data were linked to physician billing data to allow indication-specific analyses. Following conversion to the defined daily dose (DDD), the Holt-Winters exponential smoothing method was used to project expected antibiotic use in the period after implementation based on use prior to implementation. Differences between expected and observed utilization rates were calculated., Results: Overall antibiotic use has stabilized in recent years (16.2 DDD/1000 population/day in 2008). Fluoroquinolone use remains high (1.5 DDD/1000 population/day), as does the steadily increasing use of newer macrolides (1.1 to 2.7 DDD/1000 population/day between 1996 and 2008). Encouraging declines in overall and indication-specific prescription rates among children were observed. Following 3 years of DBND activities, antibiotic use was 5.8% lower than expected and the number of prescriptions dispensed to children was 10.6% lower than expected., Conclusions: This ecological study reports improvements in antibiotic use that occurred simultaneously to the delivery of the DBND program in Vancouver. However, we did not find a lowering of all targeted classes. Policy directives limiting the use of certain antibiotics may be required.

The purpose of this study was to describe the geographic distribution and model the ecological niche for Borrelia burgdorferi (Johnson, Schmidt, Hyde, Steigerwaldt & Brenner), Ixodes pacificus (Cooley & Kohls), and Ixodes angustus (Neumann), the bacterium and primary tick vectors for Lyme disease, in British Columbia (BC), Canada. We employed a landscape epidemiology approach using geographic information systems mapping and ecological niche modeling (Genetic Algorithm for Rule-set Prediction) to identify geographical areas of disease transmission risk. Forecasted optimal ecological niche areas for B. burgdorferi are focused along the coast of Vancouver Island, the southwestern coast of the BC mainland, and in valley systems of interior BC roughly along and below the N51 degree line of latitude. These findings have been used to increase public and physician awareness of Lyme disease risk, and prioritize future field sampling for ticks in BC.

Geographic Information Systems (GIS) analysis of 34 forecasted high West Nile virus (WNV) risk communities in British Columbia (BC), Canada was useful to assess feasibility and planning of the operational logistics of an emergency spray event in advance of a WNV outbreak. The geographic coverage and operational time required to perform ground- and aerial-based ultra-low volume (ULV) adulticiding were calculated using GIS. The mean geographic coverages of the ground-, aerial-, and combination of ground- and aerial-based adulticiding strategies were 39%, 61%, and 69%, respectively. The driving distance, driving time, and number of treatment nights required to perform ground-based spraying of an entire community were also calculated. Due to the large variability of treatment coverage estimates within and among the communities, no single treatment method was identified as the best strategy for province-wide ULV adulticiding in BC. Instead, the strategy for each community should be examined individually with local knowledge and expertise.