Routine HIV testing in acute care hospitals: Changing practice to curb a local HIV epidemic in Vancouver, BC.

Early treatment of HIV infection increases life expectancy and reduces infectivity; however, delayed HIV diagnosis remains common. Implementation and sustainability of hospital-based routine HIV testing in Vancouver, British Columbia, was evaluated to address a local HIV epidemic by facilitating earlier diagnosis and treatment. Public health issued a recommendation in 2011 to offer HIV testing to all patients presenting to three Vancouver hospitals as part of routine care, including all patients admitted to medical/surgical units with expansion to emergency departments (ED). We evaluated acceptability, feasibility, and effectiveness from 2011 to 2014 and continued monitoring through 2016 for sustainability. Between October 2011-December 2016, 114,803 HIV tests were administered at the three hospitals; an 11-fold increase following implementation of routine testing. The rate of testing was sustained and remained high through 2018. Of those tested, 151 patients were diagnosed with HIV for a testing yield of 0.13%. Review of 12,996 charts demonstrated 4935/5876 (96·9%) of admitted patients agreed to have an HIV test when offered. People diagnosed in hospital were significantly more likely to be diagnosed with acute stage (aOR 1·96, 95% CI 1·19, 3·23) infection, particularly those diagnosed in the ED. This study provides practice-based evidence of the feasibility, acceptability, and effectiveness of implementing a recommendation for routine HIV testing among inpatient and emergency department admissions, as well as the ability to normalize and sustain this change. Routine hospital-based HIV testing can increase diagnoses of acute HIV infection and facilitate earlier initiation of antiretroviral treatment.

Reconciling randomized trial evidence on proximal versus distal outcomes, with application to trials of influenza vaccination for healthcare workers.

When synthesizing the body of evidence concerning a clinical intervention, impacts on both proximal and distal outcome variables may be relevant. Assessments will be more defensible if results concerning a proximal outcome align with those concerning a corresponding distal outcome. We present a method to assess the coherence of empirical clinical trial results with biologic and mathematical first principles in situations where the intervention can only plausibly impact the distal outcome indirectly via the proximal outcome. The method comprises a probabilistic sensitivity analysis, where plausible ranges for key parameters are specified, resulting in a constellation of plausible pairs of estimated intervention effects, for the proximal and distal outcomes, respectively. Both outcome misclassification and sampling variability are reflected in the method. We apply our methodology in the context of cluster randomized trials to evaluate the impacts of vaccinating healthcare workers on the health of elderly patients, where the proximal outcome is suspected influenza and the distal outcome is death. However, there is scope to apply the method for other interventions in other disease areas.

Safety of a Modified Community Trailer to Manage Patients with Presumed Fentanyl Overdose.

Opioid overdoses (OD) cause substantial morbidity and mortality globally, and current emergency management is typically limited to supportive care, with variable emphasis on harm reduction and addictions treatment. Our urban setting has a high concentration of patients with presumed fentanyl OD, which places a burden on both pre-hospital and emergency department (ED) resources. From December 13, 2016, to March 1, 2017, we placed a modified trailer away from an ED but near the center of the expected area of high OD and accepted low-risk patients with presumed fentanyl OD. We provided OD treatment as well as on-site harm reduction, addictions care, and community resources. The primary outcome was the proportion of patients requiring transfer to an ED for clinical deterioration, while secondary outcomes were the proportion of patients initiated on opioid agonists and provided take-home naloxone kits. We treated 269 patients with opioid OD, transferred three (1.1%) to a local ED, started 43 (16.0%) on opioid agonists, and provided 220 (81.7%) with THN. Our program appears to be safe and may serve as a model for other settings dealing with a large numbers of opioid OD.

The Cost-Effectiveness of Human Immunodeficiency Virus Testing and Treatment Engagement Initiatives in British Columbia, Canada: 2011-2013.

Background: Recognition of the secondary preventive benefits of antiretroviral therapy (ART) has mobilized global efforts to "seek, test, treat, and retain" people living with human immunodeficiency virus [HIV]/AIDS (PLHIV) in HIV care. We aimed to determine the cost-effectiveness of a set of HIV testing and treatment engagement interventions initiated in British Columbia, Canada, in 2011-2013. Methods: Using a previously validated dynamic HIV transmission model, linked individual-level health administrative data for PLHIV, and aggregate-level HIV testing data, we estimated the cost-effectiveness of primary care testing (hospital, emergency department [ED], outpatient), ART initiation, and ART retention initiatives vs a counterfactual scenario that approximated the status quo. HIV incidence, mortality, costs (in 2015$CDN), quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios were estimated. Analyses were executed over 5- to 25-year time horizons from a government-payer perspective. Results: ED testing was the best value at $30216 per QALY gained and had the greatest impact on incidence and mortality among PLHIV, while ART initiation provided the greatest QALY gains. The ART retention initiative was not cost-effective. Delivered in combination at the observed scale and sustained throughout the study period, we estimated a 12.8% reduction in cumulative HIV incidence and a 4.7% reduction in deaths among PLHIV at $55258 per QALY gained. Results were most sensitive to uncertainty in the number of undiagnosed PLHIV. Conclusions: HIV testing and ART initiation interventions were cost-effective, while the ART retention intervention was not. Developing strategies to reengage PLHIV lost to care is a priority moving forward.

Outbreak of Vibrio parahaemolyticus Associated with Consumption of Raw Oysters in Canada, 2015.

There has been a steady increase in illness incidence of Vibrio parahaemolyticus (Vp). The majority of illnesses are associated with consumption of raw oysters. In the summer of 2015, Canada experienced the largest outbreak associated with the consumption of raw oysters harvested from British Columbia (BC) coastal waters. Case investigation of laboratory-confirmed cases was conducted to collect information on exposures and to assist traceback. Investigations at processors and oyster sampling were conducted. Eighty-two laboratory-confirmed cases of Vp infection were reported between January 1 and October 26, 2015. The majority of the cases were reported in BC, associated with consumption of raw BC oysters in restaurants. Sea surface temperatures were above the historical levels in 2015. This outbreak identified the need to improve surveillance and response to increases in human cases of Vp. This is of particular importance due to the potential for increasing water temperatures and the likelihood of additional outbreaks of Vibrio.

Avian Influenza A(H7N9) Virus Infection in 2 Travelers Returning from China to Canada, January 2015.

In January 2015, British Columbia, Canada, reported avian influenza A(H7N9) virus infection in 2 travelers returning from China who sought outpatient care for typical influenza-like illness. There was no further spread, but serosurvey findings showed broad population susceptibility to H7N9 virus. Travel history and timely notification are critical to emerging pathogen detection and response.

Whole-Genome Sequencing of Measles Virus Genotypes H1 and D8 During Outbreaks of Infection Following the 2010 Olympic Winter Games Reveals Viral Transmission Routes.

We used whole-genome sequencing to investigate a dual-genotype outbreak of measles occurring after the XXI Olympic Winter Games in Vancouver, Canada. By sequencing 27 complete genomes from H1 and D8 genotype measles viruses isolated from outbreak cases, we estimated the virus mutation rate, determined that person-to-person transmission is typically associated with 0 mutations between isolates, and established that a single introduction of H1 virus led to the expansion of the outbreak beyond Vancouver. This is the largest measles genomics project to date, revealing novel aspects of measles virus genetics and providing new insights into transmission of this reemerging viral pathogen.

Seroprevalence of hepatitis C and correlates of seropositivity among men who have sex with men in Vancouver, Canada: a cross-sectional survey.

OBJECTIVES: We sought to determine the prevalence of hepatitis C virus (HCV) infection among men who have sex with men (MSM) in Vancouver, Canada, and associations of risk behaviours with HCV serostatus. METHODS: We used data from the ManCount Study, a cross-sectional survey of MSM selected through a venue-based, time-location sampling method. Bivariate analyses and multivariate logistic regression modelling were used to determine correlates of HCV seropositivity. Bivariate analyses of participants who reported no history of injection drug use (IDU) were used to explore sexual behaviours associated with HCV seropositivity. RESULTS: HCV seroprevalence was 4.9% (56/1132). Among HCV-seropositive participants who responded to the question, 22.4% (11/49) were unaware of their HCV-seropositive status, 84.9% (45/53) reported a history of IDU and 60.7% (34/56) were HIV positive by dried blood spot. Multivariate modelling found previous IDU (adjusted OR (AOR): 26.30, 95% CI 11.15 to 62.03), receiving goods, drugs or money for sex (AOR 4.98, 95% CI 2.43 to 10.20) and current smoking (AOR 3.46, 95% CI 1.47 to 8.16) were associated with HCV seropositivity. Among MSM who reported no history of IDU, HCV seropositivity was associated with bleeding after receptive anal sex (p=0.001) and a previous diagnosis of gonorrhoea (p=0.007). CONCLUSIONS: HCV seroprevalence among a sample of MSM is higher than the general population and associated with a history of IDU. Among those who did not report IDU, we found evidence that suggests sexual exposure could be the route of transmission.

Optimizing an HIV testing program using a system dynamics model of the continuum of care.

Realizing the full individual and population-wide benefits of antiretroviral therapy for human immunodeficiency virus (HIV) infection requires an efficient mechanism of HIV-related health service delivery. We developed a system dynamics model of the continuum of HIV care in Vancouver, Canada, which reflects key activities and decisions in the delivery of antiretroviral therapy, including HIV testing, linkage to care, and long-term retention in care and treatment. To measure the influence of operational interventions on population health outcomes, we incorporated an HIV transmission component into the model. We determined optimal resource allocations among targeted and routine testing programs to minimize new HIV infections over five years in Vancouver. Simulation scenarios assumed various constraints informed by the local health policy. The project was conducted in close collaboration with the local health care providers, Vancouver Coastal Health Authority and Providence Health Care.

Systematic community- and hospital-based surveillance for enterovirus-D68 in three Canadian provinces, August to December 2014.

Respiratory specimens collected from outpatients with influenza-like illness in three Canadian provinces (British Columbia (BC), Alberta and Quebec) participating in a community-based sentinel surveillance network were prospectively screened for enterovirus-D68 (EV-D68) from 1 August to 31 December 2014 and compared to specimens collected from 1 October 2013 to 31 July 2014. Eighteen (1%) of 1,894 specimens were EV-D68-positive: 1/348 (0.3%) collected from October to December 2013 and 11/460 (2.4%) from October to December 2014, an eight-fold increase in detection rates (p=0.01), consistent with epidemic circulation in autumn 2014. The remaining EV-D68 detections were in September 2014 (6/37). Enhanced passive surveillance was also conducted on all inpatient and outpatient EV-D68 cases (n=211) detected at the BC provincial reference laboratory from 28 August to 31 December 2014. Incidence of hospitalisations was 3/100,000 overall and 21, 17, 4 and 1/100,000 among those<5, 5-9, 10-19 and ≥20-years-old with male-to-female ratios>1 among paediatric but not adult cases. Three cases in BC with comorbidity or co-infection died and five exhibited neurological features persisting >9 months. Active surveillance in outpatient and inpatient settings is needed from more areas and additional seasons to better understand EV-D68 epidemiology and potential at-risk groups for severe or unusual manifestations.

Impact of statistical adjustment for frequency of venue attendance in a venue-based survey of men who have sex with men.

Venue sampling is a common sampling method for populations of men who have sex with men (MSM); however, men who visit venues frequently are more likely to be recruited. While statistical adjustment methods are recommended, these have received scant attention in the literature. We developed a novel approach to adjust for frequency of venue attendance (FVA) and assess the impact of associated bias in the ManCount Study, a venue-based survey of MSM conducted in Vancouver, British Columbia, Canada, in 2008-2009 to measure the prevalence of human immunodeficiency virus and other infections and associated behaviors. Sampling weights were determined from an abbreviated list of questions on venue attendance and were used to adjust estimates of prevalence for health and behavioral indicators using a Bayesian, model-based approach. We found little effect of FVA adjustment on biological or sexual behavior indicators (primary outcomes); however, adjustment for FVA did result in differences in the prevalence of demographic indicators, testing behaviors, and a small number of additional variables. While these findings are reassuring and lend credence to unadjusted prevalence estimates from this venue-based survey, adjustment for FVA did shed important insights on MSM subpopulations that were not well represented in the sample.

Risks for HIV and other sexually transmitted infections among Asian men who have sex with men in Vancouver, British Columbia: a cross-sectional survey.

BACKGROUND: Individuals of Asian heritage represent the largest ethnic minority in Canada. Approximately 10% of the new HIV diagnoses in men in British Columbia occur among Asian-Canadians. However, the HIV risk patterns of Asian men who have sex with men (MSM) have not been extensively studied. METHODS: Participants aged ≥ 19 years were enrolled in a venue-based HIV serobehavioural survey of MSM in Vancouver, Canada. We compared the demographic characteristics, risk behaviours, and prevalence of HIV and other sexual and blood borne infections between Asian and non-Asian MSM using bivariate analysis and logistic regression confounder modelling. RESULTS: Amongst 1132 participants, 110 (9.7%) self-identified as Asian. Asian participants were younger than non-Asian participants (median age 29 vs. 32 years; p < 0.001), but otherwise did not differ from other study participants. HIV prevalence was lower among Asian MSM compared to Non-Asian MSM (3.7% vs 19.0%, p <0.001). Among men who self-reported as HIV negative or unknown we found no differences in unprotected anal intercourse (UAI) with a discordant or unknown serostatus partner in the previous six months (11 vs. 13%; p = 0.503). However, Asian MSM were less likely to report ever using injection drugs (10.8% vs. 19.2%; p = 0.043) or using alcohol before having sex (52% vs. 64.4%; p = 0.017). CONCLUSIONS: Asian MSM in our study reported similar rates of UAI as non-Asian MSM, but had a lower prevalence of HIV infection. Other factors, such as the use of drugs and alcohol, in relation to sex, may partly explain these differences. However this requires further investigation.

Mental health-related healthcare service utilisation and psychotropic drug dispensation trends in British Columbia during COVID-19 pandemic: a population-based study.

Background: The impact of the COVID-19 pandemic on the population's mental health is vital for informing public health policy and decision-making. However, information on mental health-related healthcare service utilisation trends beyond the first year of the pandemic is limited. Aims: We examined mental health-related healthcare service utilisation patterns and psychotropic drug dispensations in British Columbia, Canada, during the COVID-19 pandemic compared with the prepandemic period. Methods: We conducted a retrospective population-based secondary analysis using administrative health data to capture outpatient physician visits, emergency department visits, hospital admissions and psychotropic drug dispensations. We examined time trends of mental health-related healthcare service utilisation and psychotropic drug dispensations between January to December 2019 (prepandemic period) and January 2020 to December 2021 (pandemic period). In addition, we calculated age-standardised rates and rate ratios to compare mental health-related healthcare service utilisation before and during the first two years of the COVID-19 pandemic, stratified by year, sex, age and condition. Results: By late 2020, except for emergency department visits, utilisation of healthcare services recovered to prepandemic levels. Between 2019 and 2021, the monthly average rate for overall mental health-related outpatient physician visits, emergency department visits and psychotropic drug dispensations increased significantly by 24%, 5% and 8%, respectively. Notable and statistically significant increases were observed among 10-14 year-olds (44% in outpatient physician visits, 30% in emergency department visits, 55% in hospital admissions and 35% in psychotropic drug dispensations) and 15-19 year-olds (45% in outpatient physician visits, 14% in emergency department visits, 18% in hospital admissions and 34% in psychotropic drug dispensations). Additionally, these increases were more prominent among females than males, with some variation for specific mental health-related conditions. Conclusions: The increase in mental health-related healthcare service utilisation and psychotropic drug dispensations during the pandemic likely reflects significant societal consequences of both the pandemic and pandemic management measures. Recovery efforts in British Columbia should consider these findings, especially among the most affected subpopulations, such as adolescents.

British Columbia's COVID-19 surveys on population experiences, action, and knowledge (SPEAK): methods and key findings from two large cross-sectional online surveys.

OBJECTIVES: To describe the methodology and key findings of British Columbia's (BC) COVID-19 SPEAK surveys, developed to understand the experiences, knowledge, and impact of the COVID-19 pandemic on British Columbians. METHODS: Two province-wide, cross-sectional, web-based population health surveys were conducted one year apart (May 2020 and April/May 2021). Questions were drawn from validated sources grounded within the social determinants of health to assess COVID-19 testing and prevention; mental and physical health; risk and protective factors; and healthcare, social, and economic impacts during the pandemic. Quota-based non-probability sampling by geography was applied to recruit a representative sample aged 18 years and older. Recruitment included strategic outreach and longitudinal follow-up of a subgroup of respondents from round one to round two. Post-collection weighting using Census data by age, sex, education, ethnicity, and geography was conducted. RESULTS: Participants included 394,382 and 188,561 British Columbians for the first and second surveys, respectively, including a longitudinal subgroup of 141,728. Key findings showed that societal impacts, both early in the pandemic and one year later, were inequitably distributed. Families with children, young adults, and people from lower socioeconomic backgrounds have been most impacted. Significant negative impacts on mental health and stress and a deterioration in protective resiliency factors were found. CONCLUSION: These population health surveys consisting of two large cross-sectional samples provided valuable insight into the impacts and experiences of British Columbians early in the pandemic and one year later. Timely, actionable data informed several high-priority public health areas during BC's response to the COVID-19 pandemic.

RéSUMé: OBJECTIFS: Décrire la méthode et les principaux constats des enquêtes SPEAK de la Colombie-Britannique sur la COVID-19, élaborées pour comprendre l'expérience des Britanno-Colombiens durant la pandémie, ainsi que leurs connaissances de la pandémie et les effets qu'elle a eus sur eux. MéTHODE: Deux enquêtes en ligne transversales sur la santé de la population ont été menées dans toute la province à un an d'intervalle (en mai 2020 et en avril-mai 2021). Les questions, qui provenaient de sources validées ancrées dans les déterminants sociaux de la santé, ont servi à évaluer le dépistage et la prévention de la COVID-19; la santé mentale et physique; les facteurs de risque et de protection; et les effets sociaux, économiques et sur les soins de santé ressentis durant la pandémie. Un échantillonnage contingentaire non probabiliste par lieu géographique a été appliqué pour recruter un échantillon représentatif de personnes de 18 ans et plus. Le recrutement a inclus une prise de contact stratégique et un suivi longitudinal auprès d'un sous-groupe de répondants entre les cycles un et deux. Après la collecte, les données ont été pondérées selon l'âge, le sexe, le niveau d'instruction, l'ethnicité et le lieu géographique à l'aide des données du Recensement. RéSULTATS: Les participants étaient 394 382 Britanno-Colombiens au cours du premier cycle de l'enquête et 188 561 au deuxième cycle, dont un sous-groupe longitudinal de 141 728 personnes. Selon les principaux constats, la répartition des effets sociétaux, tant au début de la pandémie qu'un an plus tard, a été inéquitable. Les familles avec enfants, les jeunes adultes et les personnes de statut socioéconomique plus faible ont été les plus touchés. D'importants effets nuisibles sur la santé mentale et le stress ont été constatés, ainsi qu'une détérioration des facteurs de résilience protecteurs. CONCLUSION: Ces enquêtes sur la santé de la population comprenant deux grands échantillons transversaux ont jeté un éclairage précieux sur les effets subis et les expériences vécues par les Britanno-Colombiens au début de la pandémie et un an plus tard. Ces données opportunes et exploitables ont éclairé plusieurs domaines hautement prioritaires de la santé publique durant la riposte de la Colombie-Britannique à la pandémie de COVID-19.

Implications for HIV prevention programs from a serobehavioural survey of men who have sex with men in Vancouver, British Columbia: the ManCount study.

BACKGROUND: We examined HIV prevalence, awareness of HIV serostatus and HIV risk behaviour among a sample of men who have sex with men (MSM) in Vancouver. METHODS: MSM > or = 18 years were recruited from August 2008 to February 2009 through community venues. Participants completed a questionnaire and provided a dried blood spot (DBS) for HIV and other STI testing. We performed descriptive statistics and bivariate analyses of key explanatory variables. RESULTS: A total of 1,169 participants completed questionnaires; of these, 1,138 (97.3%) provided DBS specimens suitable for testing. The median age was 33 years (IQR 26-44). A total of 206 (18%) were HIV-positive by DBS, of whom 86% were aware they were positive. HIV seropositivity increased from 7.1% in those < 30 years of age to 19% in those 30-44 years and 34% among those > or = 45 years (p < 0.001 for test of trend). Of the 933 who self-reported as HIV-negative or unknown, 28 (3.0%) tested HIV-positive. Among those not tested for HIV in the previous 2 years, the reasons for not testing differed between participants with undiagnosed HIV infection and those who were HIV-negative. A total of 62% of study participants who self-reported as HIV-negative reported using a condom the last time they had anal sex. The use of risk-reduction measures was reported by 91.1% of all study participants (72% if excluding consistent condom use). CONCLUSION: The majority of MSM in Vancouver have adopted behaviours that reduce their HIV-related risk. However, prevention programs must continue to promote condom use, increase HIV testing, and better inform MSM of the value and limitations of other risk-reduction strategies.

A qualitative model of the HIV care continuum in Vancouver, Canada.

A team of health care stakeholders and researchers collaboratively developed a qualitative model and graphic representation of the continuum of HIV care in Vancouver to inform delivery of antiretroviral therapy and other HIV health services. The model describes the patient journey through the HIV care continuum, including states of infection, health services, and care decisions. We used a Unified Modelling Language (UML) activity diagram to capture patient and provider activities and to guide the construction of a UML state machine diagram. The state machine diagram captures model agent states in a formalism that facilitates the development of system dynamics or agent-based models. These quantitative models can be applied to optimizing the allocation of resources, and to evaluate potential strategies for improved patient care and system performance. The novel approach of combining UML diagrams we present provides a general method for modelling capacity ---management strategies within complex health systems.

Public health recommendations for athletes attending sporting events.

Public health planning in advance of the 2010 Olympic and Paralympic Winter Games included an assessment of potential public health risks for athletes attending the Games and mitigation activities to reduce those risks, including provision of vaccination recommendations to athletes. Physicians providing care to athletes who will attend large sporting events at home or abroad should consider their need for routine and additional vaccinations well in advance of the event to permit completion of vaccination schedules, ensure development of immunity, and avoid adverse vaccine reactions in the final stages of athlete training. Specific vaccinations recommended will vary depending on the location of the event and time of year it is scheduled. Other simple prevention measures for athletes include hand washing recommendations, avoiding high-risk foods, practicing safe sex, and taking simple precautions to reduce the risk of injuries. No major public health problems occurred during the 2010 Winter Games, but a measles outbreak began in Vancouver coincident in time with the Games; no known cases occurred among participating athletes.

Stability of hepatitis B viral load during pregnancy and implications for antepartum prophylaxis: A prospective cohort study.

BACKGROUND: We examined changes in hepatitis B virus (HBV) viral loads (VLs) in pregnancy, their association with hepatitis B e antigen (HBeAg), and the associated infant outcomes. METHODS: We prospectively followed 132 mothers positive for hepatitis B surface antigen (HBsAg) and their 135 infants from 2011 to 2015 in Vancouver, British Columbia. Outcome measures included association between maternal HBeAg and high (>200,000 IU/mL) or low (≤200,000 IU/mL) HBV VL, changes in HBV VL through pregnancy, infant HBsAg status, and infant completion of the HBV vaccination series. RESULTS: f the 91 participants with an available HBV VL, 13 (14.3%) had an HBV VL of more than 200,000 IU/mL. Of 59 participants with paired HBeAg and HBV VL in pregnancy, 6 had an HBV VL of more than 200,000 IU/mL; of interest, 2 of the 6 (33.3%) were HBeAg-negative. Thirty-eight participants had HBV VL results at both mid-trimester and delivery. For these 38 participants, Wilcoxon signed-ranks test for paired data found that an HBV VL remained stable (p = .58). We observed no perinatal transmissions. However, 20.7% of infants did not have a documented complete HBV vaccination series, 20.0% did not have post-vaccination HBsAg testing completed, and 18% did not have anti-HBs titres measured by age 12 months. CONCLUSIONS: Our study demonstrates that HBeAg and HBV VL are not reliably predictive of each other. This supports the improved predictive value of VL measurement in pregnancy to risk stratify pregnant patients to offer antiviral treatment when indicated and further minimize the risk of perinatal transmission.

Large community outbreak of Streptococcus pneumoniae serotype 5 invasive infection in an impoverished, urban population.

BACKGROUND: Streptococcus pneumoniae is a common cause of sporadic invasive infections, but outbreaks of invasive pneumococcal disease are infrequent. In August 2006, a sudden increase in the number of patients presenting with invasive pneumococcal disease was noted at St. Paul's Hospital (Vancouver, Canada). Most patients with severe disease resided in an area referred to as the Downtown Eastside, a neighborhood known for its high rates of poverty and illicit drug use. METHODS: Prospective, laboratory-based surveillance for invasive pneumococcal disease was initiated, including on-site serotyping of S. pneumoniae isolates. A vaccination campaign using 23-valent polysaccharide pneumococcal vaccine was launched in the Downtown Eastside. Multiple logistic regression was used to examine the association of sociodemographic variables and medical risk factors with S. pneumoniae serotype status. RESULTS: A single S. pneumoniae serotype (serotype 5) was responsible for 78% of invasive pneumococcal disease cases (137 of 175 cases) during the outbreak period of August 2006-July 2007. The outbreak strain, although fully susceptible to penicillin, caused significant morbidity and placed considerable strain on the acute care system within the Vancouver Coastal Health region. Crack cocaine use was found to be the main independent risk factor associated with invasive pneumococcal disease due to S. pneumoniae serotype 5 (odds ratio, 12.4; 95% confidence interval, 2.22-69.5). CONCLUSIONS: A targeted vaccination campaign using polysaccharide pneumococcal vaccine appeared to help control this outbreak. In urban centers with high rates of illicit drug use, vaccination strategies for preventing invasive pneumococcal disease may need to be refined to include individuals who use crack cocaine.