The impact of infection on population health: results of the Ontario burden of infectious diseases study

Real-world hepatitis C prevalence and treatment uptake at opioid agonist therapy clinics in Ontario, Canada

Widespread screening for hepatitis C virus (HCV) is necessary for Canada to meet its HCV elimination goals by 2030. People who currently or previously injected drugs are at high risk for HCV. Opioid agonist therapy (OAT, such as methadone and buprenorphine) has been shown to help stabilize the lives of people who are opioid-dependent. The distribution of OAT in North America typically requires daily, weekly, or monthly clinic visits and presents an opportunity for engagement, screening and treatment for those at high-risk of HCV. In this study, HCV screening was conducted by staff at OAT clinics in Ontario from 2016 to 2020 and those with chronic infections were treated on-site with direct-acting antivirals. Point-of-care or dried blood spot (DBS) testing was used for antibodies, DBS or serum for HCV RNA and serum for HCV RNA at SVR12 (sustained virological response). Clinics screened 1954 people (mean age 40 years ±12, 63% male). Forty-five percent were antibody positive, of whom 64% were HCV RNA+. Eighty percent of those RNA+ set an appointment in which 99% attended. Ninety-six percent started treatment with 87% completing treatment. Sixty-eight percent of people who completed treatment submitted a sample for SVR12 testing of which 97% achieved a virological cure. Results suggest that HCV screening and treatment at OAT clinics is feasible, effective and warrants expansion. Data suggest strong treatment adherence due to high rates of SVR12 comparable with other OAT-based HCV treatment programs. The lack of SVR12 sampling could be addressed by either on-site phlebotomy or incentivizing SVR12 sampling.

Ignored and undervalued in public health: a systematic review of health state utility values associated with syphilis infection

BACKGROUND

Syphilis is a sexually transmitted infection causing significant global morbidity and mortality. To inform policymaking and economic evaluation studies for syphilis, we summarised utility and disability weights for health states associated with syphilis.

METHODS

We conducted a systematic review, searching six databases for economic evaluations and primary valuation studies related to syphilis from January 2000 to February 2022. We extracted health state utility values or disability weights, including identification of how these were derived. The study was registered in the international prospective register of systematic reviews (PROSPERO, CRD42021230035).

FINDINGS

Of 3401 studies screened, 22 economic evaluations, two primary studies providing condition-specific measures, and 13 burden of disease studies were included. Fifteen economic evaluations reported outcomes as disability-adjusted life years (DALYs) and seven reported quality-adjusted life years (QALYs). Fourteen of 15 economic evaluations that used DALYS based their values on the original Global Burden of Disease (GBD) study from 1990 (published in 1996). For the seven QALY-related economic evaluations, the methodology varied between studies, with some studies using assumptions and others creating utility weights or converting them from disability weights.

INTERPRETATION

We found a limited evidence base for the valuation of health states for syphilis, a lack of transparency for the development of existing health state utility values, and inconsistencies in the application of these values to estimate DALYs and QALYs. Further research is required to expand the evidence base so that policymakers can access accurate and well-informed economic evaluations to allocate resources to address syphilis and implement syphilis programs that are cost-effective.

Epidemiological manifestations and impact of healthcare-associated infections in Libyan national hospitals

BACKGROUND

Healthcare-associated infection is a serious global problem, particularly in developing countries. In North African countries, comprehensive research on the incidence and effects of such infections is rare. This study evaluated the epidemiology and determined the impact of healthcare-associated infections in Libyan national teaching hospitals.

METHODS

A prospective longitudinal study was carried out in Libya's four largest teaching and referral hospitals (Tripoli Medical Center, Tripoli-Central Hospital, Benghazi Medical Center, and Sabha Medical Center) from November 1, 2021, to October 31, 2022. The epidemiological events and the parameters incorporated in this study were based on the data published by the Libyan Centers for Disease Control. The surveillance was carried out on all patients admitted to the wards of medicine, surgery, intensive care, gynecology & obstetrics, and pediatrics in all four hospitals. Trained staff reviewed the medical records and compared the percentages of patients with healthcare-associated infections. Bio-statistical and multivariable logistic regression analyses were carried out to test the variables associated with healthcare-associated infections and the resulting deaths.

RESULTS

A total of 22,170 hospitalized patients in four hospitals were included in the study. Hospital-acquired infection was reported in 3037 patients (13.7%; 95% CI: 12.9-14.4%). The highest incidence was in Benghazi Medical Center (17.9%; 95% CI: 16.9-18.7%), followed by Sabha Medical Center (14.8%; 95% CI:14.9-16.51%). Surgical site infection was the most prevalent (31.3%), followed by ventilator-associated pneumonia (29.3%), urinary tract infection (26.8%), and bloodstream infection (12.6%). Patients with healthcare-associated infections experienced severe morbidity requiring intervention. New antimicrobial regimens were needed for 1836 patients (93%), and 752 patients (34%) required admission to intensive care. Surgical intervention, respiratory support, and inotropes were also needed as a consequence of HAI events.

CONCLUSIONS

The high incidence of healthcare-associated infections in Libyan hospitals should be considered a major problem and a serious burden. This should alert healthcare authorities at the national and hospital levels to the urgent need for preventive and control strategies to combat hospital-acquired infections.

Clinical utility of prior positive cultures to optimize empiric antibiotic therapy selection: A cross-sectional analysis

Background

Despite reduced infectious disease mortality and improved survival, infectious diseases continue to pose health threats due to their contagiousness, societal harm, and morbidity. Empiric antibiotic therapy, often prescribed without knowledge of the causative pathogen, faces challenges from rising antibiotic resistance. This study explores the potential of prior positive culture results to guide empiric antibiotic therapy.

Methods

Data from King Abdullah University Hospital (Jan 2014-Dec 2019) included adult patients with recurrent bacterial infections (pneumonia, sepsis, UTIs, wounds). Excluded cases included: mixed infections, transfers, <14 days or >12 months between episodes. The study compared bacterial growth and sensitivity patterns between previous and recent cultures.

Results

The study included 970 episodes from 650 patients, mainly UTIs (60.3%) and gram-negative bacteria (77.9%). The study found that (65.1%) of culture pairs matched. Empirical therapy was accurate in (71.8%) of cases. Further, accuracy of selected empiric antibiotic therapy was significantly predicted (p ​< ​0.001) by: type of infection, type of antibiotics, and concordance with prior microbiologic data. Multivariate logistic analysis showed blood culture as less predictive of pending identity (OR: 0.234, P ​< ​0.001) compared to urine culture; and prior affirmed gram negative bacterial culture was less predictive (OR: 0.606, P ​= ​0.021) compared to gram positive bacterial culture.

Conclusion

This study underscores the potential of prior positive culture results in guiding empiric antibiotic therapy, enhancing accuracy and identity agreement. Future research should explore this approach in different infection contexts and across multiple centers. Reducing the indiscriminate use of broad-spectrum antibiotics is essential to combat antibiotic resistance.

Challenges in the Vaccination of the Elderly and Strategies for Improvement

In recent years, the elderly has become a rapidly growing proportion of the world's population as life expectancy is extending. Immunosenescence and inflammaging contribute to the increased risk of chronic non-communicable and acute infectious diseases. Frailty is highly prevalent in the elderly and is associated with an impaired immune response, a higher propensity to infection, and a lower response to vaccines. Additionally, the presence of uncontrolled comorbid diseases in the elderly also contributes to sarcopenia and frailty. Vaccine-preventable diseases that threaten the elderly include influenza, pneumococcal infection, herpes zoster, and COVID-19, which contribute to significant disability-adjusted life years lost. Previous studies had shown that conventional vaccines only yielded suboptimal protection that wanes rapidly in a shorter time. This article reviews published papers on several vaccination strategies that were developed for the elderly to solve these problems: more immunogenic vaccine formulations using larger doses of antigen, stronger vaccine adjuvants, recombinant subunit or protein conjugated vaccines, newly developed mRNA vaccines, giving booster shots, and exploring alternative routes of administration. Included also are several publications on senolytic medications under investigation to boost the immune system and vaccine response in the elderly. With all those in regard, the currently recommended vaccines for the elderly are presented.

Knowledge and awareness of chronic hepatitis C and liver fibrosis among health care personnel and other domains in Iraq

As a significant public health disease, the Hepatitis C virus (HCV) infects more than 185 million worldwide. Chronic infections are led by 170 million illnesses, resulting in 350,000 because of liver and cirrhosis cancer. Injuring of chronic liver from several insults leads to occur fibrosis. For example, metabolic disease (nonalcoholic fatty liver disease), infections (hepatitis B [HBV] and C viruses [HCV]), and toxins (alcohol). This study evaluates the knowledge and awareness about Of Chronic Hepatitis C and Liver Fibrosis among Health Care Workers and other domains of workers in Iraq. This study was carried out as cross-sectional research in Diyala, Iraq, from February / 2021 to January / 2022. In this work, 350 persons participated; the age range was (18-62) years, with a mean age of (25.9 + 9.79). The participants consisted of 100 males and 250 females. Also, they were divided into two groups: groups I and II. I (health care workers group) consists of 200 students studying in the medical department of Baquba technical institute and workers in Diyala hospitals ). Group II (other domains Workers) includes (100) participants who work in several domains. Similar to previous studies, a questionnaire was adopted to collect this research data. The outcomes demonstrate higher knowledge about HCV, Liver fibrosis, transmission, and a vaccine was noticed with a statistically significant difference among females compared to males. Regarding residency, the ability of HCV and liver fibrosis in Q1, Q2, and Q5 only among Health Care Workers compared to other domains Workers with a statistically significant difference (P<0.05). Keywords: Chronic Hepatitis C, Liver Fibrosis, Health Care Workers and other domains Workers

Cost-effectiveness modelling of birth and infant dose vaccination against hepatitis B virus in Ontario from 2020 to 2050

BACKGROUND

The World Health Organization recommends universal birth dose vaccination for hepatitis B virus (HBV), yet only 3 provinces and territories in Canada provide birth dose vaccination, and Canadian-born children in Ontario are acquiring HBV before adolescent vaccination. We sought to determine whether birth and/or infant HBV vaccination is cost-effective.

METHODS

We used a dynamic HBV model that incorporates population by year, disease stage, sex and the influence of immigration to quantify the disease and economic burden of chronic HBV infection in Ontario from 2020 to 2050. We compared 4 vaccination scenarios, which included a birth dose vaccine and variations of the 2 subsequent doses (either alone or as a part of the hexavalent vaccine) and a hexavalent-only strategy in infancy with the current adolescent vaccination strategy. Our costing estimates were based on values from 2020.

RESULTS

All 4 infant vaccination approaches prevented an additional 550-560 acute and 160 chronic pediatric HBV infections from 2020 to 2050 compared with adolescent vaccination. Whereas birth dose could be cost-effective, incorporating vaccination into a hexavalent vaccine was cost saving. By 2050, the hexavalent approach led to $428 000 in cost savings per disability-adjusted life years averted.

INTERPRETATION

At the current prevalence in Ontario, a switch to birth dose or infant dose will be cost-effective or even cost saving. Introducing any form of infant HBV immunization in Ontario will prevent acute and chronic pediatric HBV infections.

The epidemiology and healthcare costs of community-acquired pneumonia in Ontario, Canada: a population-based cohort study

OBJECTIVES

The aim of the present study was to determine incidence-based short- and long-term healthcare costs attributable to community-acquired pneumonia (CAP) from the healthcare payer perspective in Ontario, Canada.

METHODS

We conducted a retrospective population-based matched cohort study of residents in Ontario, Canada using health administrative data. We identified subjects with an incident episode of CAP (exposed subjects) between 1 January 2012 and 31 December 2014. The index date of each episode was based on the first inpatient or outpatient claim for pneumonia. Exposed subjects were matched without replacement to unexposed subjects from the general population using hard and propensity score matching on age, sex, income quintile, rural residence, comorbidities, and healthcare costs prior to index date. Attributable costs represented the mean difference in costs between the exposed subjects and their matched pairs.

RESULTS

We identified 692,090 subjects with at least one episode of CAP between 1 January 2012 and 31 December 2014. Adults aged 65 years and older had the highest annual incidence rate of 50.1 episodes per 1,000 person-years, while adults aged 18-64 years and children (aged 0-17) had incidence rates of 12.9 and 24.7 episodes per 1,000 person-years, respectively. The majority of episodes involved care exclusively in the outpatient setting (92.6%), with most of these episodes involving a single physician visit. The mean attributable costs were $1,595 (95% CI: $1,572-$1,616) per outpatient CAP episode and $12,576 (95% CI: $12.392-$12,761) per inpatient CAP episode. Attributable costs were significantly higher for adult subjects and those with time spent in the intensive care unit. Alternative case definitions yielded different results, although demonstrated the same overall trends across groups.

CONCLUSION

CAP is associated with substantially increased acute and long-term healthcare costs compared to unexposed subjects. This study highlights the burden of CAP in both the inpatient and outpatient setting, and will serve to inform strategic healthcare planning for future interventions and healthcare programs.

The impact of influenza on the ability to work, volunteer and provide care: results from an online survey of Canadian adults 50 years and older

Background

Influenza is associated with a decline in functional abilities among Canadian older adults, although specific impacts on daily life have not been fully explored.

Methods

In August 2019 and May 2020, we conducted surveys of Canadian adults 50-64 years and 65 years and older through an online market research platform. The survey included questions about the impact of diagnosed influenza or self-reported influenza-like-illness (ILI) on working, volunteering and caregiving.

Results

We surveyed 1006 adults in the 50-64 year age group about the 2018/19 season and 1001 about the 2019/20 season. In the 65 years and older age group, we surveyed 3548 and 3500 individuals about the 2018/19 and 2019/20 influenza seasons, respectively. In each season, nearly two-thirds of individuals 50-64 years with influenza/ILI were employed; 51.7% reported absenteeism in 2018/19 and 53.6% in 2019/20. Of the 20% of individuals 65 years and older who were employed, 47.0% of those with influenza/ILI were absent while ill in 2018/19 (39.8% in 2019/20). In 2018/2019, 29.6% of respondents 50-64 years old with influenza/ILI identified as volunteers (29.3% in 2019/2020). In both seasons, nearly half were unable to do so while ill. Of the 164 (32.7%) individuals 65 years and older who volunteered during the 2018/19 season, 80 (48.8%) did not while ill; 224 (37.3%) respondents volunteered in the 2019/20 season, and half were absent while ill. Of those 50-64 years with influenza/ILI, 97 (42.2%) and 57 (22.2%) were caregivers in 2018/19 and 2019/20, respectively. In 2018/19 and 2019/20, 40 (41.2%) and 28 (49.1%) caregivers were unable to provide care when ill, respectively. Of those with influenza/ILI in the 65 years and older age group, 123 (24.6%) and 162 (27.0%) were caregivers in 2018/19 and 2019/20, respectively. In 2018/19, 18 (14.6%) caregivers with influenza/ILI did not provide care while ill (42 [25.9%] in 2019/20).

Discussion

In Canadian older adults, influenza and ILI had notable impacts on ability to volunteer and provide care across two recent seasons. Optimization of influenza prevention in this population may yield important societal benefits.

Differential Overlap in Human and Animal Fecal Microbiomes and Resistomes in Rural versus Urban Bangladesh

While the development of antibiotic resistance in animal gut microbiomes and subsequent transmission to humans has been demonstrated in intensive farming environments and high-income countries, evidence of zoonotic exchange of antibiotic resistance in LMIC communities is lacking. This research provides genomic evidence of overlap of antibiotic resistance genes between humans and animals, especially in urban communities, and highlights chickens as important reservoirs of antibiotic resistance.

Cost-effectiveness analysis of hepatitis C virus (HCV) point-of-care assay for HCV screening

BACKGROUND & AIMS

Hepatitis C virus (HCV) continues to pose significant public health concerns with approximately 44% of chronically infected Canadians undiagnosed. The current HCV screening in Canada is a two-step diagnosis pathway consisting of anti-HCV testing and HCV ribonucleic acid (RNA) testing. The introduction of HCV point-of-care assays, such as the Xpert HCV viral load finger-stick assay, can facilitate HCV RNA diagnosis during a single visit and provide quick linkage to care. We evaluated the cost-effectiveness of HCV point-of-care testing compared with current HCV screening strategies for injection drug users (IDUs) from a Canadian provincial Ministry of Health perspective.

METHODS

A state-transition model based on published literature was developed to compare HCV point-of-care assay with the standard-of-care blood screening for a one-time HCV screening and treatment program. It adopted a lifetime time horizon and included health states related to treatment, fibrosis stages, and advanced liver disease clinical states. Outcomes were expressed in costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios. Sensitivity analyses were conducted to assess the robustness of the model.

RESULTS

HCV point-of-care assay generated an additional 0.035 QALYs/person at a cost reduction of $21.15 compared with the standard-of-care screening. The results were the most sensitive to the specificity of HCV point-of-care assay.

CONCLUSIONS

The implementation of HCV point-of-care screening in Canada is likely to be cost-saving for IDUs. Early detection and treatment of undiagnosed individuals can prolong people's life span and save healthcare costs associated with HCV-related complications.

Meta-synthesis and science mapping analysis of HIV/HPV co-infection: a global perspective with emphasis on Africa

Background

Viral infections are emerging with diverse clinical relevance both in endemic environments and non-endemic regions of the world. Some of the viruses cause co-infections that are of public health importance. The progress of studies on human immunodeficiency virus / Human papillomavirus (HIV/HPV) co-infection is not well documented especially in Africa where cases are endemic.

Method

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a global three-decade meta-synthesis and science mapping analysis on HIV/HPV co-infections. Assessment of progress, Author/Country productivity/trends, topic conceptual framework, and international collaborative networks were analyzed.

Results

We recovered 196 documents of 115 sources from the web of science database. The meta-synthesis revealed 1203 prolific authors containing nine solo authors, an annual growth rate of 8.09%, a significant average citation per article of 20.7%, and an average citation per year per document of 2.1. A significant high correlation between the mean/TC per article and the mean total citation (TC) per year showed 80.98% of the articles produced between 2005 and 2007 on HPV/HIV co-infection. The co-author per document index were 7.0 and the collaboration index was 6.4. The meta-analysis also revealed inadequate funding from individual or governmental organizations; among the 196 documents dataset, 114 (58.2%) were funded, and only 31 (15.8%) were funded in Africa where HIV/HPV co-infection cases are endemic.

Conclusions

Authors’ collaboration network, countries’ collaboration, authors’ citations and implementation of research-based finding in previous studies are yet to receive the relevant outcome, especially as various countries in the African continent have received poor funding with a repeated reporting of co-infection associated with HIV/HPV. African needs to re-awaken and stir up research-based interest in HPV/HIV co-infection studies to resolve indigenous public health concerns associated with the viral endemicity.

Uptake and factors associated with direct-acting antiviral therapy for hepatitis C and treatment outcomes among Canadian immigrants: A retrospective cohort analysis

BACKGROUND: We sought to compare rates and factors associated with Direct Acting Antiviral (DAA) treatment uptake and sustained virological response (SVR) between Canadian-born and foreign-born patients.

METHODS: The study was conducted utilizing a retrospective cohort of hepatitis C virus (HCV)-infected patients assessed at The Ottawa Hospital Viral Hepatitis Clinic between January 2015 and October 2021. Risk factors, income, and clinical characteristics of HCV infection associated with DAA therapy uptake and SVR were compared by immigration status using logistic regression.

RESULTS: Of 1,459 HCV-infected patients, 264 (18.1%) were born outside of the country. A median 17 years passed from immigration to first assessment at the clinic. The proportion of patients initiating DAA therapy was similar between groups (65.2% versus 69.5%, p = 0.17). Characteristics associated with DAA therapy uptake included age at first assessment (OR = 1.02; 95% CI 1.01 to 1.03) and being cirrhotic (OR = 3.19; 95% CI 1.99 to 2.13). Crude SVR rate was higher in immigrants than in Canadian-born patients (91.5% versus 83.7%, p = 0.01). After controlling for other variables, only advancing age was associated with the likelihood of achieving crude SVR (OR = 1.04, 95% CI 1.02 to 1.05).

CONCLUSIONS: We found that DAA therapy uptake and HCV cure rates were high in both groups suggesting equity of opportunity in those referred to our program. The older age at presentation suggests missed opportunities to diagnose and engage immigrants in HCV care. These findings emphasize the importance of early large-scale screening and engagement in care for HCV infection of immigrant populations to prevent future complications.

A collaborative approach to hepatitis C testing in two First Nations communities of Northwest Ontario

BACKGROUND: Two remote First Nations communities each collaborated with an urban-based liver clinic to organize wide-spread testing, followed by linkage to care for hepatitis C virus (HCV). METHOD: Involvement of community members was central to planning and conduct of the programs. Samples were obtained using dry blood spot cards (DBS). A week-long pilot study in Community 1 investigated the effectiveness of the program, using DBS. Community 2, being larger, more remote, and known to be endemic for HCV was more challenging. Three-week-long testing drives plus a stand-alone testing day were used to collect samples over 5 months. Public Health Agency (PHAC)’s National Laboratory for HIV Reference Services (NLHRS) received and tested the DBS samples for HCV and other blood-borne infections. Outcomes were measured by number of people tested, the quality of the tests, and community members’ satisfaction with the program and retained knowledge about HCV, based on interviews. RESULTS: In Community 1, 226 people were tested for HCV over 4 days. 85% agreed to human immunodeficiency virus (HIV) testing as well. In Community 2, 484 people, one-half of the adult population, were tested. Surveys of participants showed food was the most significant draw, and Facebook the most effective way to inform people of the events. Interviews with staff and participants showed a high level of satisfaction. CONCLUSION: The results suggest this is an effective approach to testing for HCV in unusually challenging settings. Lessons from the program include the power of community involvement; and the effectiveness of a highly targeted health initiative when developed through collaboration.

The impact of electronic medical record system implementation on HCV screening and continuum of care: a systematic review

INTRODUCTION AND OBJECTIVES

Hepatitis C (HCV) screening is imperative to meet WHO elimination targets including increased detection and reduced mortality. An electronic medical record (EMR) system can be utilized in health care centers to indicate if a patient should be targeted for HCV screening, thus increasing the number of those offered testing.

MATERIALS AND METHODS

We examined English language publications reporting on the impact of EMR system utilization on HCV screening and the HCV continuum of care. Relevant papers were identified using multiple search engines to search key terms. Clinical outcomes considered included any or no change in HCV screening rates following EMR system introduction, as well as any or no change in rates of patients progressing along the HCV cascade of care after diagnosis once an EMR system was implemented.

RESULTS

From a search pool of 18 studies, 11 meet inclusion criteria and reported on the selected clinical outcomes. Each outcome assessed indicated that use of an EMR system increased the proportion of patients offered and/or receiving HCV testing. We were unable to conclude if an EMR system had an impact on the number of patients progressing along the HCV cascade of care following a positive test result. Overall, all methods of implementation of an EMR system had the same outcome of increasing screening rates.

CONCLUSIONS

EMR system utilization had a positive impact on increasing HCV screening. However, the clinical effectiveness of utilizing an EMR system to help eliminate transmission and increase HCV treatment cure rates requires further study.

Attitudes and perceptions of mothers towards childhood vaccination in Greece: lessons to improve the childhood COVID-19 vaccination acceptance

BACKGROUND

Maternal attitudes and beliefs have been shown to influence childhood vaccination coverage, resulting in under-vaccination, non-vaccination, and vaccination delay. This study aimed to investigate the mothers' attitudes and perceptions about vaccination for their children in Greece.

METHODS

This was an online cross-sectional study, conducted from 4 April to 8 June 2020. A self-administered questionnaire was used to collect information about mothers' and their children's socio-demographic characteristics, previous vaccination behavior, and mothers' attitudes and perceptions about childhood vaccination. Participants included adult mothers with at least one minor child.

RESULTS

One thousand eight hundred eighty-five mothers participated, with the majority (91.7%) believing in the usefulness of vaccines and that vaccines protect children from serious and life-threatening diseases. A larger percentage of mothers with higher educational attainment agreed/absolutely agreed that all vaccinations provided by the National Vaccination Program must be offered to their children (91.6%) (p = 0.02) and that vaccines protect children from serious and life-threatening diseases (92.9%) (p = 0.01). Significant more married/in cohabitation and not single-parent mothers agreed that vaccines are safe (53.5% and 53.4%, respectively). There were also several significant associations between maternal attitudes toward childhood vaccination and previous maternal vaccination practices [(e.g., adherence to recommended vaccination dosages (all p-values < 0.01), vaccination delays (all p-values < 0.05), and vaccination during pregnancy (all p-values < 0.01)].

CONCLUSION

Maternal attitudes and perceptions toward childhood vaccination are significantly influenced by sociodemographic factors and maternal vaccination practices. Revealing those is essential for public health officials in developing future strategies to improve childhood vaccination coverage and acceptance of new vaccines such as the COVID-19 vaccine.

Estimating the population health burden of Lyme disease in Ontario, Canada: a microsimulation modelling approach

BACKGROUND

If untreated, Lyme disease can lead to long-term sequelae and post-treatment Lyme disease syndrome (PTLDS), resulting in reduced health-related quality of life. The objective of this study was to develop a microsimulation model to estimate the population-level health burden of Lyme disease in Ontario, Canada.

METHODS

We developed a Lyme disease history model using microsimulation, simulating 100 000 people (mean age 37.6 yr, 51% female) from 2017 in Ontario over a lifetime risk of infection and time horizon. We extracted the sensitivity and specificity of the 2-tier testing recommended by the Canadian Public Health Laboratory Network, probabilities and health state utility values from the published literature and health administrative data. Our reported outcomes from our stochastic analysis include diagnosed cases of Lyme disease (stratified by stage), undiagnosed infections, sequelae, individuals with PTLDS and quality-adjusted life-years (QALYs) lost.

RESULTS

Our model estimated 333 (95% confidence interval [CI] 329-337) infections over the lifetime of 100 000 simulated people (mean age 37.6 yr, 51% female), with 92% (95% CI 91%-93%) of infections diagnosed. Of those 308 people with Lyme Disease diagnoses, 67 (95% CI 65-69) developed sequelae (e.g., arthritic, cardiac, neurologic sequelae), and 34 (95% CI 33-35) developed PTLDS. Lyme disease resulted in a loss of 84.5 QALYs (95% CI 82.9-86.2) over the lifetime of the simulated cohort. Sensitivity and scenario analysis showed that increasing incidence rates of Lyme disease, potential underreporting, duration of PTLDS and quality of life (health state utility) associated with PTLDS had the greatest impact on health burden.

INTERPRETATION

Lyme disease contributes considerable health burden in terms of QALYs lost. Our analysis provides evidence to understand the disease burden and lays the foundation to assess the cost-effectiveness of pharmaceutical and nonpharmaceutical interventions.

Infections and the development of childhood acute lymphoblastic leukemia: a population-based study

An infectious trigger for childhood acute lymphoblastic leukemia is hypothesized and we assessed the association between the rate, type, and critical exposure period for infections and the development of acute lymphoblastic leukemia. We conducted a matched case-control study using administrative databases to evaluate the association between the rate of infections and childhood acute lymphoblastic leukemia diagnosed between the ages of 2-14 years from Ontario, Canada and we used a validated approach to measure infections. In 1600 cases of acute lymphoblastic leukemia, and 16 000 matched cancer-free controls aged 2-14 years, having >2 infections/year increased the odds of childhood acute lymphoblastic leukemia by 43% (odds ratio = 1.43, 95% confidence interval 1.13-1.81) compared to children with ≤0.25 infections/year. Having >2 respiratory infections/year increased odds of acute lymphoblastic leukemia by 28% (odds ratio =1.28, 95% confidence interval 1.05-1.57) compared to children with ≤0.25 respiratory infections/year. Having an invasive infection increased the odds of acute lymphoblastic leukemia by 72% (odds ratio =1.72, 95% confidence interval 1.31-2.26). Having an infection between the age of 1-1.5 years increased the odds of acute lymphoblastic leukemia by 20% (odds ratio = 1.20, 95% confidence interval 1.04-1.39). Having more infections increased the odds of developing childhood acute lymphoblastic leukemia and having an infection between the ages of 1-1.5 years increased the odds of childhood acute lymphoblastic leukemia.

Liver Fibrosis in Human Immunodeficiency Virus (HIV)-Hepatitis C Virus (HCV) Coinfection Before and After Sustained Virologic Response: What Is the Best Noninvasive Marker for Monitoring Regression?

BACKGROUND

Noninvasive markers of liver fibrosis such as aspartate aminotransferase-to-platelet ratio (APRI) and transient elastography (TE) have largely replaced liver biopsy for staging hepatitis C virus (HCV). As there is little longitudinal data, we compared changes in these markers before and after sustained virologic response (SVR) in human immunodeficiency virus (HIV)-HCV coinfected patients.

METHODS

Participants from the Canadian Coinfection Cohort study who achieved SVR after a first treatment with either interferon/ribavirin or direct acting antivirals (DAAs), with at least 1 pre- and posttreatment fibrosis measure were selected. Changes in APRI or TE (DAA era only) were modeled using a generalized additive mixed model, assuming a gamma distribution and adjusting for sex, age at HCV acquisition, duration of HCV infection, and time-dependent body mass index, binge drinking, and detectable HIV RNA.

RESULTS

Of 1981 patients, 151 achieved SVR with interferon and 553 with DAAs; 94 and 382 met inclusion criteria, respectively. In the DAA era, APRI increased (0.03 units/year; 95% credible interval (CrI): -.05, .12) before, declined dramatically during, and then changed minimally (-0.03 units/year; 95% CrI: -.06, .01) after treatment. TE values, however, increased (0.74 kPa/year; 95% CrI: .36, 1.14) before treatment, changed little by the end of treatment, and then declined (-0.55 kPa/year; 95% CrI: -.80, -.31) after SVR.

CONCLUSIONS

TE should be the preferred noninvasive tool for monitoring fibrosis regression following cure. Future studies should assess the risk of liver-related outcomes such as hepatocellular carcinoma according to trajectories of fibrosis regression measured using TE to determine if and when it will become safe to discontinue screening.

Viral hepatitis C cascade of care: A population-level comparison of immigrant and long-term residents

BACKGROUND & AIMS

Viral hepatitis C represents a major global burden, particularly among immigrant-receiving countries such as Canada, where knowledge of disparities in hepatitis C virus among immigrant groups for micro-elimination efforts is lacking. We quantify the hepatitis C cascades of care among immigrants and long-term residents prior to the introduction of direct-acting antiviral medications.

METHODS

Using laboratory and health administrative records, we described the hepatitis C virus cascades of care in terms of diagnosis, engagement with care, treatment initiation, and clearance in Ontario, Canada (1997-2014). We stratified the cascade by immigrant and long-term resident groups and identify drivers at each stage using multivariable Poisson regression.

RESULTS

We included 940 245 individuals in the study with an estimated hepatitis C prevalence of 167 923 (1.4%) overall, 23 759 (0.7%) among all immigrants, and 6019 (1.1%) among immigrants from hepatitis C endemic countries. Overall there were 104 616 individuals with reactive antibody results, 73 861 tested for viral RNA, 52 388 with viral RNA detected, 50 805 genotyped, 13 159 on treatment and 3919 with evidence of viral clearance. Compared to long-term residents, immigrants showed increased nucleic-acid testing (aRR: 1.09 [95%CI: 1.08, 1.10]), treatment initiation (aRR: 1.46 [95%CI: 1.38, 1.54]), and higher clearance rates (aRR: 1.07 [95%CI: 1.03, 1.11]).

CONCLUSIONS

Hepatitis C virus is more prevalent among long-term residents compared to immigrants overall, however, immigrants from endemic countries are an important subgroup to consider for future screening and linkage to care initiatives. These findings are prior to the introduction of newer medications and provide a population-based benchmark for follow-up studies and evaluation of treatment programs and surveillance activities.

Different approaches to quantify years of life lost from COVID-19

The burden of an epidemic is often characterized by death counts, but this can be misleading as it fails to acknowledge the age of the deceased patients. Years of life lost is therefore widely used as a more relevant metric, however, such calculations in the context of COVID-19 are all biased upwards: patients dying from COVID-19 are typically multimorbid, having far worse life expectation than the general population. These questions are quantitatively investigated using a unique Hungarian dataset that contains individual patient level data on comorbidities for all COVID-19 deaths in the country. To account for the comorbidities of the patients, a parametric survival model using 11 important long-term conditions was used to estimate a more realistic years of life lost. As of 12 May, 2021, Hungary reported a total of 27,837 deaths from COVID-19 in patients above 50 years of age. The usual calculation indicates 10.5 years of life lost for each death, which decreases to 9.2 years per death after adjusting for 11 comorbidities. The expected number of years lost implied by the life table, reflecting the mortality of a developed country just before the pandemic is 11.1 years. The years of life lost due to COVID-19 in Hungary is therefore 12% or 1.3 years per death lower when accounting for the comorbidities and is below its expected value, but how this should be interpreted is still a matter of debate. Further research is warranted on how to optimally integrate this information into epidemiologic risk assessments during a pandemic.

Validating viral hepatitis B and C diagnosis codes: a retrospective analysis using Ontario's health administrative data

OBJECTIVE

We aimed to determine the criterion validity of using diagnosis codes for hepatitis B virus (HBV) and hepatitis C virus (HCV) to identify infections.

METHODS

Using linked laboratory and administrative data in Ontario, Canada, from January 2004 to December 2014, we validated HBV/HCV diagnosis codes against laboratory-confirmed infections. Performance measures (sensitivity, specificity, and positive predictive value) were estimated via cross-validated logistic regression and we explored variations by varying time windows from 1 to 5 years before (i.e., prognostic prediction) and after (i.e., diagnostic prediction) the date of laboratory confirmation. Subgroup analyses were performed among immigrants, males, baby boomers, and females to examine the robustness of these measures.

RESULTS

A total of 1,599,023 individuals were tested for HBV and 840,924 for HCV, with a resulting 41,714 (2.7%) and 58,563 (7.0%) infections identified, respectively. HBV/HCV diagnosis codes ± 3 years of laboratory confirmation showed high specificity (99.9% HBV; 99.8% HCV), moderate positive predictive value (70.3% HBV; 85.8% HCV), and low sensitivity (12.8% HBV; 30.8% HCV). Varying the time window resulted in limited changes to performance measures. Diagnostic models consistently outperformed prognostic models. No major differences were observed among subgroups.

CONCLUSION

HBV/HCV codes should not be the only source used for monitoring the population burden of these infections, due to low sensitivity and moderate positive predictive values. These results underscore the importance of ongoing laboratory and reportable disease surveillance systems for monitoring viral hepatitis in Ontario.

Prenatal hepatitis B screening, and hepatitis B burden among children, in Ontario: a descriptive study

BACKGROUND

Ontario is 1 of 5 provinces that immunize adolescents for hepatitis B virus (HBV), despite the World Health Organization recommendation for universal birth dose vaccination. One rationale for not vaccinating at birth is that universal prenatal screening and related interventions prevent vertical transmission. The aims of our study were to evaluate the uptake and epidemiology of prenatal HBV screening, and to determine the number of children in Ontario with a diagnosis of HBV before adolescent vaccination.

METHODS

We extracted data from ICES, Public Health Ontario and Better Outcomes & Registry Network (BORN) Ontario databases. We assessed prenatal screening uptake and prevalence of prenatal hepatitis B surface antigen (HBsAg) from 2012 to 2016, as well as subsequent hepatitis B e-antigen (HBeAg) and HBV DNA testing and percent positivity. We used age and region to subcategorize the results. In a separate unlinked analysis, we evaluated the number of children positive for HBV aged 0-11 years who were born in Ontario from 2003 to 2013.

RESULTS

From 2012 to 2016, 93% of pregnant women were screened for HBV, with an HBsAg prevalence of 0.6%. Prevalence of HBsAg increased with age, peaking at older than 45 years at 3%. North Toronto had the highest overall prevalence of 1.5%, whereas northern Ontario had the lowest. Of women who were HBsAg positive, HBeAg and HBV DNA tests were subsequently ordered in 13% and 38%, respectively. Of children born in Ontario between 2003 and 2013, 139 of 23 759 tested positive for HBV.

INTERPRETATION

Prenatal HBV screening is not universal and subsequent evaluation is poor, limiting optimal intervention and possibly contributing to some Ontario-born children being given a diagnosis of HBV before age 12 years. These findings underscore the limitations of the province's adolescent vaccination strategy.

Vaccines for older adults

The proportion of the global population aged 65 and older is rapidly increasing. Infections in this age group, most recently with SARS-CoV-2, cause substantial morbidity and mortality. Major improvements have been made in vaccines for older people, either through the addition of novel adjuvants-as in the new recombinant zoster vaccine and an adjuvanted influenza vaccine-or by increasing antigen concentration, as in influenza vaccines. In this article we review improvements in immunization for the three most important vaccine preventable diseases of aging. The recombinant zoster vaccine has an efficacy of 90% that is minimally affected by the age of the person being vaccinated and persists for more than four years. Increasing antigen dose or inclusion of adjuvant has improved the immunogenicity of influenza vaccines in older adults, although the relative effectiveness of the enhanced influenza vaccines and the durability of the immune response are the focus of ongoing clinical trials. Conjugate and polysaccharide pneumococcal vaccines have similar efficacy against invasive pneumococcal disease and pneumococcal pneumonia caused by vaccine serotypes in older adults. Their relative value varies by setting, depending on the prevalence of vaccine serotypes, largely related to conjugate vaccine coverage in children. Improved efficacy will increase public confidence and uptake of these vaccines. Co-administration of these vaccines is feasible and important for maximal uptake in older people. Development of new vaccine platforms has accelerated following the arrival of SARS-CoV-2, and will likely result in new vaccines against other pathogens in the future.

Peri-complication diagnosis of hepatitis C infection: Risk factors and trends over time

BACKGROUND & AIMS

Hepatitis C virus (HCV) is a common and treatable cause of cirrhosis and its complications, yet many chronically infected individuals remain undiagnosed until a late stage. We sought to identify the frequency of and risk factors for HCV diagnosis peri-complication, that is within six months of an advanced liver disease complication.

METHODS

This was a retrospective cohort study of Ontario residents diagnosed with chronic HCV infection between 2003 and 2014. HCV diagnosis peri-complication was defined as the occurrence of decompensated cirrhosis, hepatocellular carcinoma or liver transplant within ±6 months of HCV diagnosis. Multivariable logistic regression was used to identify risk factors for peri-complication diagnosis among all those diagnosed with HCV infection.

RESULTS

Our cohort included 39,515 patients with chronic HCV infection, of whom 4.2% (n = 1645) were diagnosed peri-complication; these represented 31.6% of the 5,202 patients who developed complications in the follow-up period. Peri-complication diagnosis became more common over the study period and was associated with increasing age among baby boomers, alcohol use, diabetes mellitus, chronic HBV co-infection and moderate to high levels of morbidity. Female sex, immigrant status, having more previous outpatient physician visits, a previous emergency department visit, a history of drug use or mental health visits were associated with reduced risk of peri-complication diagnosis.

CONCLUSIONS

Over a quarter of HCV-infected patients with complications were diagnosed peri-complication. This problem increased over time, suggesting a need to further expand HCV screening.

Spending on Hepatitis C Antivirals in the United States and Canada, 2014 to 2018

OBJECTIVES

Hepatitis C virus (HCV) antivirals have been shown to be highly effective with minimal adverse effects, but they are costly. Little is known about the national spending on this drug class in either Canada or the United States, 2 countries with different drug pricing regulations. Thus the objective of this study was to compare drug expenditure on HCV medications in the United States and Canada.

METHODS

This was a retrospective cross-sectional study using the IQVIA National Sales Perspectives (United States) and Geographic Prescription Monitor (Canada) databases, which contains prescription transactions from American and Canadian pharmacies. All prescription claims for the period between January 1, 2014, and June 30, 2018, were used to describe HCV antiviral expenditure in both countries.

RESULTS

The United States and Canada spent $59.7 billion and $2.8 billion on HCV medications, respectively. Population-adjusted HCV medication costs were higher in the United States ($1 million per 100 000 population) compared with Canada ($0.4 million per 100 000 population).

CONCLUSIONS

Although the rates of HCV infection are similar in the 2 countries, these findings highlight the differences in both the reimbursement utilization policy for HCV treatments in the countries and the major differences in drug pricing policies. As policies to reduce drug spending in the United States are explored, this article highlights the potential cost implications of implementing Canadian index pricing.

Association of Influenza Activity and Environmental Conditions With the Risk of Invasive Pneumococcal Disease

IMPORTANCE

Streptococcus pneumoniae is the most commonly identified cause of bacterial pneumonia, and invasive pneumococcal disease (IPD) has a high case fatality rate. The wintertime coseasonality of influenza and IPD in temperate countries has suggested that pathogen-pathogen interaction or environmental conditions may contribute to IPD risk.

OBJECTIVES

To evaluate the short-term associations of influenza activity and environmental exposures with IPD risk in temperate countries and to examine the generalizability of such associations across multiple jurisdictions.

DESIGN, SETTING, AND PARTICIPANTS

This case-crossover analysis of 19 566 individuals with IPD from 1998 to 2011 combined individual-level outcomes of IPD and population-level exposures. Participants lived in 12 jurisdictions in Canada (the province of Alberta and cities of Toronto, Vancouver, and Halifax), Australia (Perth, Sydney, Adelaide, Brisbane, and Melbourne), and the United States (Baltimore, Providence, and Philadelphia). Data were analyzed in 2019.

EXPOSURES

Influenza activity, mean temperature, absolute humidity, and UV radiation at delays of 1 to 3 weeks before case occurrence in each jurisdiction.

MAIN OUTCOMES AND MEASURES

Matched odds ratios (ORs) for IPD associated with changes in exposure variables, estimated using multivariable conditional logistic regression models. Heterogeneity in effects across jurisdictions were evaluated using random-effects meta-analytic models.

RESULTS

This study included 19 566 patients: 9629 from Australia (mean [SD] age, 42.8 [30.8] years; 5280 [54.8%] men), 8522 from Canada (only case date reported), and 1415 from the United States (only case date reported). In adjusted models, increased influenza activity was associated with increases in IPD risk 2 weeks later (adjusted OR [aOR] per SD increase, 1.07; 95% CI, 1.01-1.13). Increased humidity was associated with decreased IPD risk 1 week later (aOR per 1 g/m3, 0.98; 95% CI, 0.96-1.00). Other associations were heterogeneous; metaregression suggested that combinations of environmental factors might represent unique local risk signatures. For example, the heterogeneity in effects of UV radiation and humidity at a 2-week lag was partially explained by variation in temperature (UV index: coefficient, 0.0261; 95% CI, 0.0078 to 0.0444; absolute humidity: coefficient, -0.0077; 95% CI, -0.0125 to -0.0030).

CONCLUSIONS AND RELEVANCE

In this study, influenza was associated with increased IPD risk in temperate countries. This association was not explained by coseasonality or case characteristics and appears generalizable. Absolute humidity was associated with decreased IPD risk in the same jurisdictions. The generalizable nature of these associations has important implications for influenza control and advances the understanding of the seasonality of this important disease.

Impact of comprehensive care on health care use among a cohort of marginalized people living with hepatitis C in Toronto

Background: The majority of new hepatitis C (HCV) cases occur among people who inject drugs. In recent years, multidisciplinary models of HCV treatment have emerged that demonstrate successful treatment outcomes for this population, as well as broad positive individual- and system-level impacts. Our objective was to evaluate changes in health care use among a cohort of people living with HCV before and after engagement with one such program. Methods: Program data were uniquely linked to provincial health administrative databases. Rates of emergency department (ED) visits and hospital admissions of clients from 2011 through 2015 ( N = 103) were evaluated using linkages with administrative data for the 2 years before and after program initiation. Data were evaluated using negative binomial regression models with a covariance structure to account for within-individual correlations. Results: Of participants, 72.8% were men (mean age 47 years), and 38% experienced high rates of physical and mental health comorbidity (Aggregated Diagnosis Group score ≥10). Female clients had significantly fewer ED visits 2 years after program initiation (5.04 versus 3.12; risk ratio [RR] 0.61 [95% CI 0.44% to 0.86%]). ED visits for infectious diseases and soft tissue injury were significantly lower for the cohort overall (RRs 0.58 0.51 [95% CIs 0.35% to 0.95% and 0.29% to 0.90%], respectively). Conclusion: Co-locating HCV treatment within comprehensive primary care and harm reduction services appears to have benefits beyond HCV, including a reduction in ED visits among women and a decrease in ED visits for soft tissue infections for all participants.

Outbreak analytics: a developing data science for informing the response to emerging pathogens

Despite continued efforts to improve health systems worldwide, emerging pathogen epidemics remain a major public health concern. Effective response to such outbreaks relies on timely intervention, ideally informed by all available sources of data. The collection, visualization and analysis of outbreak data are becoming increasingly complex, owing to the diversity in types of data, questions and available methods to address them. Recent advances have led to the rise of outbreak analytics, an emerging data science focused on the technological and methodological aspects of the outbreak data pipeline, from collection to analysis, modelling and reporting to inform outbreak response. In this article, we assess the current state of the field. After laying out the context of outbreak response, we critically review the most common analytics components, their inter-dependencies, data requirements and the type of information they can provide to inform operations in real time. We discuss some challenges and opportunities and conclude on the potential role of outbreak analytics for improving our understanding of, and response to outbreaks of emerging pathogens.

This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control‘. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.

The role of prison-based interventions for hepatitis C virus (HCV) micro-elimination among people who inject drugs in Montréal, Canada

BACKGROUND

In Canada, hepatitis C virus (HCV) transmission primarily occurs among people who inject drugs (PWID) and people with experience in the prison system bare a disproportionate disease burden. These overlapping groups of individuals have been identified as priority populations for HCV micro-elimination in Canada, which is currently not on track to achieve its elimination targets. Considering the missed opportunities to intervene in provincial prisons, this study aims to estimate the population-level impact of prison-based interventions and post-release risk reduction strategies on HCV transmission among PWID in Montréal, a Canadian city with high HCV burden.

METHODS

A dynamic HCV transmission model among PWID was developed and calibrated to community and prison bio-behavioural surveys in Montréal. Then, the relative impact of prison-based testing and treatment or post-release linkage to care (both 90% testing and 75% treatment coverage), alone or in combination with strategies that reduce the heightened post-release transmission risk by 50%, was estimated from 2018 to 2030, and compared to counterfactual scenarios.

RESULTS

Prison-based test-and-treat strategies could lead to the greatest declines in incidence (48%; 95%CrI: 38-57%) over 2018-2030 and prevent the most new first chronic infections (22%; 95%CrI: 16-28%) among people never exposed to HCV. Prison testing and post-release linkage to care lead to a slightly lower decrease in incidence and prevented fraction of new chronic infections. Combining test-and-treat with risk reduction measures could further its epidemiological impact, preventing 35% (95%CrI: 29-40%) of new first chronic infections. When implemented concomitantly with community-based treatment scale-up, prison-based interventions had synergistic effects, averting a higher fraction of new first chronic infections.

CONCLUSION

Offering HCV testing and treatment in provincial prisons, where incarcerations are frequent and sentences short, could change the course of the HCV epidemic in Montréal. Prison-based interventions with potential integration of post-release risk reduction measures should be considered as an integral part of HCV micro-elimination strategies in this setting.

Hepatitis C Virus Screening of High-Risk Patients in a Canadian Emergency Department

BACKGROUND

Approximately 0.7% of the Canadian population is infected with hepatitis C virus (HCV), and many individuals are unaware of their infection. Our objectives were to utilize an emergency department (ED) based point-of-care (POC) HCV screening test to describe our local population and estimate the proportion of high-risk patients in our population with undiagnosed HCV.

METHODS

A convenience sample of medically stable patients (≥18 years) presenting to a community ED in Calgary, AB, between April and July 2018 underwent rapid clinical screening for HCV risk factors, including history of injection drug use, healthcare in endemic countries, and other recognized criteria. High-risk patients were offered POC HCV testing. Antibody-positive patients underwent HCV-RNA testing and were linked to hepatology care. The primary outcome was the proportion of new HCV diagnoses in the high-risk population.

RESULTS

Of the 999 patients screened by survey, 247 patients (24.7%) were high-risk and eligible for testing. Of these, 123 (49.8%) were from HCV-endemic countries, while 63 (25.5%) and 31 (12.6%) patients endorsed a history of incarceration and intravenous drug use (IVDU), respectively. A total of 144 (58.3%) eligible patients agreed to testing. Of these, 6 patients were POC-positive (4.2%, CI 0.9-7.4%); all 6 had antibodies detected on confirmatory lab testing and 4 had detectable HCV-RNA viral loads in follow-up. Notably, 103 (41.7%) patients declined POC testing. Interpretation. Among 144 high-risk patients who agreed to testing, the rate of undiagnosed HCV infection was 4.2%, and the rate of undiagnosed HCV infection with detectable viral load was 2.8%. Many patients with high-risk clinical criteria refused POC testing. It is unknown if tested and untested groups have the same disease prevalence. This study shows that ED HCV screening is feasible and that a small number of previously undiagnosed patients can be identified and linked to potentially life-changing care.

The Clinical Burden of Clostridioides difficile in Ontario, Canada

Background

To understand the clinical burden of Clostridioides difficile infection (CDI), we analyzed health outcome data from Ontario, Canada for CDI associated with and manifested in acute care hospitals (ACH), long-term care facilities (LTCF), the community, or ACH-associated with community-onset.

Methods

We performed a retrospective analysis using individual-level data from Ontario databases (April 1, 2005 to March 31, 2015), identifying CDI cases ≥18 years requiring hospitalization, and stratifying into cohorts based on association and onset location. Cohort members were matched to controls on demographics and medical conditions at onset, for outcomes including 30- and 180-day all-cause mortality and rehospitalization.

Results

We stratified 22 617 individuals hospitalized with CDI during the study period: 13 152 (58.1%) ACH-associated/ACH-onset, 7116 (31.5%) community-associated/community-onset, 1847 (8.2%) ACH-associated/community-onset, and 502 (2.2%) LTCF-associated/LTCF-onset. Compared with controls, unadjusted 30-day rehospitalization rates were significantly higher (P < .0001) for ACH-associated/ACH-onset CDI (9.5% vs 0.4%), LTCF-associated/LTCF-onset (7.2% vs 1.1%), community-associated/community-onset (7.8% vs 0.8%), and ACH-associated/community-onset (10.9% vs 0.7%). One hundred eighty-day mortality rates were higher in the community-associated/community-onset and the LTCF-associated/LTCF-onset cohorts than controls: 66.3% vs 12.3% (P < .0001) and 30.9% vs 3.1% (P < .0001), respectively. All differences remained significant after adjusting for patient factors.

Conclusions

Clostridioides difficile infection is associated with higher rates of 30-day rehospitalization compared with controls. In addition, mortality rates within 180-days of hospital discharge are significantly higher for community-associated/community-onset and LTCF-associated/LTCF-onset CDI cohorts than controls. Clostridioides difficile infection warrants increased prevention and monitoring efforts.

Incidence and economic burden of Clostridioides difficile infection in Ontario: a retrospective population-based study

BACKGROUND

Understanding the impact of prevention programs on Clostridioides difficile infection rates is important, and decisions on future program changes, including how to use vaccines currently in development, requires a detailed understanding of the epidemiologic features of C. difficile infection. We analyzed Ontario health administrative data to determine incidence rates and medical costs of C. difficile infection, based on whether acquisition and onset occurred in acute care hospitals (ACHs), long-term care facilities or the community.

METHODS

We performed a retrospective analysis using individual-level data from Ontario health databases from Apr. 1, 2005, to Mar. 31, 2015, identifying rates of C. difficile infection requiring hospital admission per 100 000 person-years in adults aged 18 years or more for categories of acquisition and onset. We estimated health care system costs of infection 180 and 365 days after admission by matching patients with C. difficile infection with control patients with similar characteristics.

RESULTS

Over the study period, 33 909 people in Ontario were admitted to hospital with C. difficile infection; 17 272 cases (50.9%) were associated with ACHs. The number of cases per 100 000 person-years ranged from 27.7 in 2009/10 to 37.0 in 2012/13. Annually, the highest incidence of infection was for ACH-associated/ACH-onset. Community-associated infection became more prevalent over time, rising from 19.4% of cases in 2005/06 to 29.2% in 2014/15. Infection costs were mostly due to hospital admission within 180 days after hospital discharge. Infection associated with ACHs had the highest total costs and the largest cost attributable to C. difficile infection (median $38 953 for infected patients v. $13 542 for control patients). Median costs attributable to C. difficile infection were $1051 for that associated with long-term care facilities, $13 249 for community-associated infection and $11 917 for ACH-associated/community-onset infection.

INTERPRETATION

Community-associated C. difficile infection had similar health care cost implications as hospital-associated infection. With rates of community-associated C. difficile infection on the rise, family physicians should be supported to prevent this infection in their patients.

Impact of Pneumococcal Vaccination on Pneumonia Hospitalizations and Related Costs in Ontario: A Population-Based Ecological Study

Background

In Ontario, Canada, pneumococcal conjugate vaccine (PCV) was approved for infants in 2001 and became part of the publicly funded routine immunization schedule in 2005. We assessed the population-level impact of PCV on pneumonia hospitalizations and related costs.

Methods

We used the difference-in-differences approach to evaluate the impact of pneumococcal vaccination on pneumonia hospitalizations and related costs, using nonpneumonia hospitalization as the control condition. We extracted monthly hospitalization costs, stratified by age group, from population-based health administrative data between April 1992 and March 2014. The study period was divided into 5 intervals: prevaccine period, availability of 7-valent PCV (PCV7) for private purchase, public funding for PCV7, replacement of PCV7 with 10-valent PCV (PCV10), and replacement of PCV10 with 13-valent PCV (PCV13).

Results

A total of 1063700 pneumonia hospitalizations were recorded during the study period. In the vaccine-eligible age group, pneumonia hospitalizations declined by 34% (95% confidence interval, 32%-37%), 38% (32%-43%), and 45% (40%-51%) and hospitalization-related costs declined by 38% (25%-51%), 39% (33%-45%), and 46% (41%-52%) after public funding for PCV7, PCV10, and PCV13, respectively. Pneumonia hospitalizations and related costs also declined substantially for PCV-ineligible older children and elderly persons (aged >65 years).

Conclusions

Our results suggest that the publicly funded PCV immunization program is responsible for substantial reductions in pneumonia hospitalizations and related healthcare costs, among both young children eligible for publicly funded vaccination and other age groups not included in the publicly funded program.

The hepatitis C virus cascade of care in a Quebec provincial prison: a retrospective cohort study

BACKGROUND

Hepatitis C virus (HCV) microelimination efforts must target people in prison; however, although some inmates may qualify for treatment in provincial prisons, it may not be routinely provided. Our aim was to characterize the cascade of HCV care in Quebec's largest provincial prison.

METHODS

We conducted a retrospective study of all HCV-related laboratory tests requested at the Établissement de détention de Montréal (men's prison with on-demand screening), between July 1, 2017, and June 30, 2018. We defined 8 HCV care cascade steps: 1) total sentenced inmates, 2) screened for HCV (via HCV antibody [HCV Ab]), 3) HCV Ab positive, 4) tested for HCV RNA, 5) HCV RNA positive, 6) linked to care, 7) HCV treatment initiated and 8) achieved sustained virologic response. We measured proportions of inmates at each step using denominator-numerator linkage. We also calculated the proportion screened among inmates with a sentence duration of at least 1 month, during which time screening should be feasible.

RESULTS

Of the 4931 sentenced inmates, 344 (7%) were screened for HCV, of whom 38 (11%) were HCV Ab positive. Thirty-five (92%) of the 38 received HCV RNA testing, which showed positivity in 16 (46%). Ten (62%) of the 16 inmates were linked to care; treatment was initiated in 3 (30%), 2 of whom (67%) achieved a sustained virologic response. Among inmates with a sentence duration of at least 1 month (n = 1972), the proportion screened increased to 17%.

INTERPRETATION

A small proportion (7%) of men at a Canadian provincial prison with on-demand HCV testing were screened, and rates of treatment initiation were low in the absence of formal HCV cure pathways. To eliminate HCV in this subpopulation, opt-out HCV testing should be considered.

Epidemiologic and clinical features of chronic hepatitis B virus infection in 8 Canadian provinces: a descriptive study by the Canadian HBV Network

BACKGROUND

Published Canadian epidemiologic data on hepatitis B virus (HBV) infection include single-centre studies or are focused on Indigenous populations. We performed a study to characterize the demographic and clinical features, liver disease status and treatment of people with chronic hepatitis B in Canada.

METHODS

In this descriptive, opportunistic, cross-sectional study, available data for people known to be monoinfected with HBV were collected by the Canadian HBV Network from existing clinical databases, with support from the National Microbiology Laboratory, Public Health Agency of Canada. Data were collected in all provinces with the exception of New Brunswick and Newfoundland and Labrador. We analyzed the data using parametric and nonparametric statistical methods, with a significance level of p < 0.05.

RESULTS

In the 9380 unique patient records reviewed, the median age was 48 years, and 5193 patients (55.4%) were male. Ethnicity information was available for 7858 patients, of whom 5803 (73.8%) were Asian, 916 (11.6%) were black and 914 (11.6%) were white. Most of those tested (5556/6796 [81.8%]) were negative for HBV e-antigen, and most of those with fibrosis data (3481/4260 [81.7%]) had minimal liver fibrosis, with more advanced fibrosis noted in older people (> 40 yr). Of the 980 patients with genotype data, 521 (53.2%) had genotype B or C infection. Most of the 9241 patients with known confirmed treatment status received tenofovir disoproxil fumarate (1655 [17.9%]), lamivudine (1434 [15.5%]) or entecavir (548 [5.9%]).

INTERPRETATION

Based on available data, Canadian patients with chronic hepatitis B are predominantly Asian and negative for HBV e-antigen, and have genotype B or C infection. Interprovincial variations were noted in antiviral treatment regimen. This multicentre nationwide study provides data regarding patients with chronic hepatitis B and may inform future studies on the epidemiologic features of HBV infection in Canada.

Impact of infectious diseases on population health using incidence-based disability-adjusted life years (DALYs): results from the Burden of Communicable Diseases in Europe study, European Union and European Economic Area countries, 2009 to 2013

The Burden of Communicable Diseases in Europe (BCoDE) study aimed to calculate disability-adjusted life years (DALYs) for 31 selected diseases in the European Union (EU) and European Economic Area (EEA). Methods: DALYs were estimated using an incidence-based and pathogen-based approach. Incidence was estimated through assessment of data availability and quality, and a correction was applied for under-estimation. Calculation of DALYs was performed with the BCoDE software toolkit without applying time discounting and age-weighting. Results: We estimated that one in 14 inhabitants experienced an infectious disease episode for a total burden of 1.38 million DALYs (95% uncertainty interval (UI): 1.25–1.5) between 2009 and 2013; 76% of which was related to the acute phase of the infection and its short-term complications. Influenza had the highest burden (30% of the total burden), followed by tuberculosis, human immunodeficiency virus (HIV) infection/AIDS and invasive pneumococcal disease (IPD). Men had the highest burden measured in DALYs (60% of the total), adults 65 years of age and over had 24% and children less than 5 years of age had 11%. Age group-specific burden showed that infants (less than 1 year of age) and elderly people (80 years of age and over) experienced the highest burden. Conclusions: These results provide baseline estimates for evaluating infectious disease prevention and control strategies. The study promotes an evidence-based approach to describing population health and assessing surveillance data availability and quality, and provides information for the planning and prioritisation of limited resources in infectious disease prevention and control.

HCV-infected individuals have higher prevalence of comorbidity and multimorbidity: a retrospective cohort study

Background

Almost 1% of Canadians are hepatitis C (HCV)-infected. The liver-specific complications of HCV are established but the extra-hepatic comorbidity, multimorbidity, and its relationship with HCV treatment, is less well known. We describe the morbidity burden for people with HCV and the relationship between multimorbidity and HCV treatment uptake and cure in the pre- and post-direct acting antiviral (DAA) era.

Methods

We linked adults with HCV at The Ottawa Hospital Viral Hepatitis Program as of April 1, 2017 to provincial health administrative data and matched on age and sex to 5 Ottawa-area residents for comparison. We used validated algorithms to identify the prevalence of mental and physical health comorbidities, as well as multimorbidity (2+ comorbidities). We calculated direct age- and sex-standardized rates of comorbidity and comparisons were made by interferon-based and interferon-free, DAA HCV treatments.

Results

The mean age of the study population was 54.5 years (SD 11.4), 65% were male. Among those with HCV, 4% were HIV co-infected, 26% had liver cirrhosis, 47% received DAA treatment, and 57% were cured of HCV. After accounting for age and sex differences, the HCV group had greater multimorbidity (prevalence ratio (PR) 1.38, 95% confidence interval (CI) 1.20 to 1.58) and physical-mental health multimorbidity (PR 2.71, 95% CI 2.29–3.20) compared to the general population. Specifically, prevalence ratios for people with HCV were significantly higher for diabetes, renal failure, cancer, asthma, chronic obstructive pulmonary disease, substance use disorder, mood and anxiety disorders and liver failure. HCV treatment and cure were not associated with multimorbidity, but treatment prevalence was significantly lower among middle-aged individuals with substance use disorders despite no differences in prevalence of cure among those treated.

Conclusion

People with HCV have a higher prevalence of comorbidity and multimorbidity compared to the general population. While HCV treatment was not associated with multimorbidity, people with substance use disorder were less likely to be treated. Our results point to the need for integrated, comprehensive models of care delivery for people with HCV.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4315-6) contains supplementary material, which is available to authorized users.

EXamining the knowledge, Attitudes and experiences of Canadian seniors Towards influenza (the EXACT survey)

Background

Older adults are at high risk for influenza-related complications including worsening frailty and function. We surveyed older Canadians to explore the impact of influenza and determine how influenza knowledge influences vaccination decision-making.

Methods

We disseminated an online survey through a national polling panel. The survey included questions about the respondents’ influenza vaccination practices and knowledge about influenza. Using validated measures, they reported their frailty and functional status prior to the 2016/17 influenza season, during illness (if applicable), and following the season. Regression analyses were used to examine predictors of poor functional outcomes.

Results

Five thousand and fourteen adults aged 65 and older completed the survey; mean age was 71.3 ± 5.17 years, 42.6% had one or more chronic conditions, 7.8% were vulnerable and 1.8% were frail. 67.9% reported receiving last season’s influenza vaccine. Those who rarely/never receive the influenza vaccine were significantly less likely to correctly answer questions about influenza’s impact than those who receive the vaccine more consistently. Of the 1035 (21.5%) who reported experiencing influenza or influenza-like illness last season, 40% indicated a recovery longer than 2 weeks, and one-fifth had health and function declines during this time. Additionally, 3.1% of those afflicted “never fully recovered”. Older age, significant trouble with memory and having influenza/ILI were among the independent predictors of persistent declines in health and function.

Conclusions

Given that frailty and function are important considerations for older adults’ well-being and independence, healthcare decision-makers must understand the potential for significant temporary and long-term impacts of influenza to make informed vaccine-related policies and recommendations.

Knowledge, attitudes, behaviours, and beliefs of healthcare provider students regarding mandatory influenza vaccination

Influenza infection poses the same risk to healthcare students as to practising clinicians. While there is substantial dialog about the benefits, risks, and ethics of mandatory influenza immunization policies in Canada, there has been little engagement of healthcare students. To explore the knowledge, attitudes, beliefs, and behaviours of healthcare students, we administered a web-based survey to students at Dalhousie University. Influenza vaccination status varied by program type, with 86.3% of medical students (n = 124) and 52.4% of nursing students (n = 96) self-reporting receipt of the influenza vaccine both in the previous and current seasons; pharmacy students' coverage fell between the two. Pharmacy students had higher mean knowledge scores (10.0 out of 13 questions) than medical (9.26) and nursing (8.88) students. Between 56.1% and 64.5% of students across disciplines were in support of a mandatory masking or vaccination policy, and between 72.6% and 82.3% of students would comply if such a policy were in place. A sense of duty to be immunized, desire to be taught more about influenza and influenza vaccine, belief that the hospital has a right to know vaccination status, support for declination policy, and willingness to accept consequences of noncompliance were all predictors of student support of mandatory policies. Medical and pharmacy students tended to hold more pro-influenza vaccination attitudes, had higher knowledge scores, and better vaccine coverage than nursing students. Based on the overall vaccination behaviour, knowledge, beliefs, and attitudes of students surveyed, this study demonstrates that mandatory influenza immunization policies are generally supported by the next generation of practitioners.

Management of Hepatitis B Virus Infection: 2018 Guidelines from the Canadian Association for the Study of Liver Disease and Association of Medical Microbiology and Infectious Disease Canada

Hepatitis B virus (HBV) infection is an important public health problem in Canada. In keeping with evolving evidence and understanding of HBV pathogenesis, the Canadian Association for the Study of Liver Disease periodically publishes HBV management guidelines. The goals of the 2018 guidelines are to (1) highlight the public health impact of HBV infection in Canada and the need to improve diagnosis and linkage to care, (2) recommend current best-practice guidelines for treatment of HBV, (3) summarize the key HBV laboratory diagnostic tests, and (4) review evidence on HBV management in special patient populations and include more detail on management of HBV in pediatric populations. An overview of novel HBV tests and therapies for HBV in development is provided to highlight the recent advances in HBV clinical research. The aim and scope of these guidelines are to serve as an up-to-date, comprehensive resource for Canadian health care providers in the management of HBV infection.

Five-year Audit of Infectious Diseases at a Tertiary Care Hospital in Karachi, Pakistan

Purpose

To estimate the burden of infectious diseases and the seasonality of mosquito-borne diseases seen at The Indus Hospital, Karachi (TIH).

Methodology

We performed a retrospective data analysis of all infectious diseases (ID) cases, retrieved from medical records over a five-year period starting from 1 January 2012 till 31 December 2016 at The Indus Hospital (TIH), which is a 150-bed, charity-based, tertiary-care health facility. The collected data has been categorized into three groups: (A) public health-related diseases, including community and environmental IDs, i.e., mosquito-borne diseases such as malaria and dengue, respiratory tract infections, diarrheal diseases, typhoid, and hepatitis; (B) systemic infection related IDs that target individual anatomical or physiological systems such as the respiratory tract, urinary tract, skin and soft tissue, and the cardiac system, and lastly, those IDs which are (C) programmatically managed at TIH, namely cases from the tuberculosis (TB), human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), and malaria clinics, and the rabies prevention center. As the study is an audit, ethical approval was waived by the institutional review board (IRB).

Result

Overall data from 71,815 patients were assessed. In the public health group (A), the main bulk of diseases were due to malaria, tuberculosis, respiratory tract infections (upper and lower), and diarrheal diseases in both males and females in descending order; there was preponderance of malaria, respiratory tract infections, and diarrheal diseases in males, and of tuberculosis among females. Among the systemic diseases group (B), urinary tract infections (UTIs) had a disproportionately high incidence, followed by skin and soft tissue infections, while bone and joint infections and diabetic foot had equal incidence. In the programmatic group (C), the highest number of cases seen was dog bites followed by drug-sensitive TB. Overall, the six most common infections were malaria, cases of dog bites, tuberculosis, respiratory tract infections, diarrheal diseases, and hepatitis C. More women than men had TB; diarrheal disease and respiratory tract infections were more common in children. UTIs were the most common systemic infections among both men and women.

Conclusion

There is a great need to have an effective surveillance mechanism of preventable diseases at the national level. Our study highlights the diversity of cases that should direct medical curriculum development, post-graduate training, and health services improvement.

Canadian older adults' perceptions of effectiveness and value of regular and high-dose influenza vaccines

Influenza vaccination is an important public health intervention for older adults, yet vaccination rates remain suboptimal. We conducted an online survey of Canadians ≥ 65 years to explore satisfaction with publicly-funded standard-dose influenza vaccines, and perceptions of the need for a more effective product. They were provided with information about currently approved influenza vaccines, and were asked about their preferences should all formulations be available for free, and should the recently approved high-dose (HD) vaccine for seniors be available at a cost. From March to April 2017, 5014 seniors completed the survey; mean age was 71.3 ± 5.17 years, 50% were female, and 42.6% had one or more chronic conditions. 3403 (67.9%) had been vaccinated against influenza in the 2016/17 season. Of all respondents, 3460 (69%) were satisfied with the standard-dose influenza vaccines, yet 3067 (61.1%) thought that a more effective vaccine was/may be needed. If HD was only available at a cost, 1426 (28.4%) respondents would consider it, of whom 62.9% would pay $20 or less. If all vaccines were free next season, 1914 (38.2%) would opt for HD (including 12.2% of those who previously rejected influenza vaccines), 856 (17.1%) would choose adjuvanted vaccine, and 558 (11.1%) standard-dose vaccine. 843 (16.8%) of respondents were against vaccines, 451 (9.0%) had no preference and 392 (7.8%) were uncertain. Making this product available through publicly funded programs may be a strategy to increase immunization rates in this population.

Addressing hepatitis C in the foreign-born population: A key to hepatitis C virus elimination in Canada

Hepatitis C virus (HCV) is the leading cause of death from infectious disease in Canada. Immigrants are an important group who are at increased risk for HCV; they account for a disproportionate number of all HCV cases in Canada (~30%) and have approximately a twofold higher prevalence of HCV (~2%) than those born in Canada. HCV-infected immigrants are more likely to develop cirrhosis and hepatocellular carcinoma and are more likely to have a liver-related death during a hospitalization than HCV-infected non-immigrants. Several factors, including lack of routine HCV screening programs in Canada for immigrants before or after arrival, lack of awareness on the part of health practitioners that immigrants are at increased risk of HCV and could benefit from screening, and several patient- and health system-level barriers that affect access to health care and treatment likely contribute to delayed diagnosis and treatment uptake. HCV screening and engagement in care among immigrants can be improved through reminders in electronic medical records that prompt practitioners to screen for HCV during clinical visits and implementation of decentralized community-based screening strategies that address cultural and language barriers. In conclusion, early screening and linkage to care for immigrants from countries with an intermediate or high prevalence of HCV would not only improve the health of this population but will be key to achieving HCV elimination in Canada. This article describes the unique barriers encountered by the foreign-born population in accessing HCV care and approaches to overcoming these barriers.

Impact of availability of direct-acting antivirals for hepatitis C on Canadian hospitalization rates, 2012-2016

Backgrounds

Hospitalizations associated with hepatitis C virus (HCV) infection and liver disease increased on average by 6.0% per year from 2004 to 2010 in Canada and were projected (in 2010) to increase by another 4% by 2016. The first generation of direct-acting antivirals (DAAs) became available in 2012. In 2014, a second generation of effective and well-tolerated DAA therapy was authorized in Canada. The impact of DAA therapy on the HCV-associated disease burden in Canada has not been documented.

Objectives

To assess the potential impact of DAA therapy on the disease burden by a) comparing the actual hospitalization rates associated with HCV infection and liver disease following the introduction of DAAs in Canada with the 2010 baseline projection and b) documenting the associated uptake of anti-HCV therapy.

Methods

The hospital records of inpatients diagnosed with chronic HCV and chronic liver disease were extracted from the Canadian Discharge Abstract Database (DAD) by fiscal year for 2004-2016. We compared the actual number of hospitalizations to the baseline projection by year and for selected 5-year birth cohorts (1925-1989). The monthly number of new prescriptions for anti-HCV regimens was extracted from the IQVIA CDH CompuScript database (formerly IMS Health), aggregated to annual levels by age group and compared with hospitalization trends.

Results

Compared to the baseline projection, there was a slight reduction in hospitalizations in 2014/15 and 2015/16. This slight reduction was followed by a more significant decline in 2016/17 (32% below expected; 95% confidence interval [CI]: 27%-37%). The largest declines were observed for patients born before 1960 (age 55 or older) at 40% below expected in 2016/17. The number of new anti-HCV prescriptions increased from 5,484 in fiscal year 2012/13 to a peak of 17,775 in 2015/2016. The number of new prescriptions corresponds to approximately 1.3 and five times the number of hospitalizations in 2012/13 and 2015/16, respectively.

Conclusions

In Canada there has been a modest decrease in HCV and liver-related hospitalizations following a significant increase in uptake of second-generation DAAs in 2015. However, the burden is still high. Linked health administrative databases created to monitor the disease burden in the new treatment era should provide additional insight with the linkage of treatment history and disease stage to individual outcomes.

Population-based estimate of hepatitis C virus prevalence in Ontario, Canada

Background

Hepatitis C virus (HCV) is the most burdensome infectious illness in Canada. Current screening strategies miss a significant proportion of cases, leaving many undiagnosed. Elevated HCV prevalence in those born between 1945 and 1965 has prompted calls for birth-cohort screening in this group. However, Canada lacks population-level data to support this recommendation. We performed a serosurvey to obtain population-based HCV prevalence estimates in Ontario residents born between 1945–1974, to generate evidence for birth-cohort screening recommendations.

Methods

We tested anonymized residual sera in five-year age-sex bands from Ontario for anti-HCV antibody. We performed descriptive epidemiological analysis and used a logistic regression model to determine HCV risk-factors.

Results

Of 10,006 sera analyzed, 155 (1.55%, 95% confidence interval (CI) 1.32, 1.81) were positive for HCV antibody. Individuals born between 1950–1964 had a significantly higher combined prevalence of 1.92% (95% CI 1.56, 2.34) compared to 1.14% (95% CI 0.69, 1.77) (p = 0.04) for those born between 1970–1974. For males, comprising 107/155 (69.03%) of positive samples, the highest prevalence was 3.00% (95% CI 1.95, 4.39) for the 1960–1964 birth-cohort. For females, the highest prevalence was 1.56% (95% CI 0.83, 2.65) for those born between 1955–1959. Male sex was significantly associated with positive HCV serostatus.

Interpretation

HCV prevalence in Ontario is highest among those in this birth cohort, and higher than previous estimates. The prevalence estimates presented in our study provide important data to underpin birth-cohort screening recommendations.