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Background Older adults are recommended to receive influenza vaccination annually, and many use statins. Statins have immunomodulatory properties that might modify influenza vaccine effectiveness (VE) and alter influenza infection risk. Methods Using the test-negative design and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against laboratory-confirmed influenza among community-dwelling statin users and nonusers aged ≥66 years during the 2010–2011 to 2018–2019 influenza seasons. We also estimated the odds ratio for influenza infection comparing statin users and nonusers by vaccination status. Results Among persons tested for influenza across the 9 seasons, 54 243 had continuous statin exposure before testing and 48 469 were deemed unexposed. The VE against laboratory-confirmed influenza was similar between statin users and nonusers (17% [95% confidence interval, 13%–20%] and 17% [13%–21%] respectively; test for interaction, P = .87). In both vaccinated and unvaccinated persons, statin users had higher odds of laboratory-confirmed influenza than nonusers (odds ratios for vaccinated and unvaccinated persons 1.15 [95% confidence interval, 1.10–1.21] and 1.15 [1.10–1.20], respectively). These findings were consistent by mean daily dose and statin type. VE did not differ between users and nonusers of other cardiovascular drugs, except for β-blockers. We did not observe that vaccinated and unvaccinated users of these drugs had increased odds of influenza, except for unvaccinated β-blocker users. Conclusions Influenza VE did not differ between statin users and nonusers. Statin use was associated with increased odds of laboratory-confirmed influenza in vaccinated and unvaccinated persons, but these associations might be affected by residual confounding.

BackgroundThe COVID-19 pandemic continues to demonstrate the risks and profound health impacts that result from infectious disease emergencies. Emergency preparedness has been defined as the knowledge, capacity and organizational systems that governments, response and recovery organizations, communities and individuals develop to anticipate, respond to, or recover from emergencies. This scoping review explored recent literature on priority areas and indicators for public health emergency preparedness (PHEP) with a focus on infectious disease emergencies.MethodsUsing scoping review methodology, a comprehensive search was conducted for indexed and grey literature with a focus on records published from 2017 and 2020 onward, respectively. Records were included if they: a) described PHEP, b) focused on an infectious emergency, and c) were published in an Organization for Economic Co-operation and Development country. An evidence-based all-hazards Resilience Framework for PHEP consisting of 11 elements was used as a reference point to identify additional areas of preparedness that have emerged in recent publications. The findings were summarized thematically.ResultsThe included publications largely aligned with the all-hazards Resilience Framework for PHEP. In particular, the elements related to collaborative networks, community engagement, risk analysis and communication were frequently observed across the publications included in this review. Emergent themes were identified that expand on the Resilience Framework for PHEP. These were related to mitigating inequities, public health capacities (vaccination, laboratory system capacity, infection prevention and control capacity, financial investment in infrastructure, public health legislation, phases of preparedness), scientific capacities (research and evidence-informed decision making, climate and environmental health), and considerations for health system capacity.ConclusionsThe themes from this review contribute to the evolving understanding of critical public health preparedness actions; however, there was a paucity of recent evidence on PHEP indicators. The themes can expand on the 11 elements outlined in the Resilience Framework for PHEP, specifically relevant to infectious disease emergencies and risks. Further research will be important to validate these findings, and expand understanding of how refinements to PHEP frameworks and indicators can support public health practice.

Background: Outbreaks cause significant morbidity and mortality in healthcare settings. Current testing methods can identify specific viral respiratory pathogens, yet the approach to outbreak management remains general. Objectives: Our aim was to examine pathogen-specific trends in respiratory outbreaks, including how attack rates, case fatality rates and outbreak duration differ by pathogen between hospitals and long-term care (LTC) and retirement homes (RH) in Ontario. Methods: Confirmed respiratory outbreaks in Ontario hospitals and LTC/RH reported between September 1, 2007, and August 31, 2017, were extracted from the integrated Public Health Information System (iPHIS). Median attack rates and outbreak duration and overall case fatality rates of pathogen-specific outbreaks were compared in both settings. Results: Over the 10-year surveillance period, 9,870 confirmed respiratory outbreaks were reported in Ontario hospitals and LTC/RH. Influenza was responsible for most outbreaks (32% in LTC/RH, 51% in hospitals), but these outbreaks were shorter and had lower attack rates than most non-influenza outbreaks in either setting. Human metapneumovirus, while uncommon (

CONTEXTE: Le deploiement de mesures de gestion des eclosions de SRAS-CoV-2 dans les etablissements de soins de longue duree en Ontario a permis d’en reduire la frequence et la gravite. Nous decrivons ici les donnees epidemiologiques et de laboratoire d’une de ces premieres eclosions en Ontario afin de determiner les facteurs associes a son importance et les impacts des interventions progressives de lutte contre les infections appliquees pendant la duree de l’eclosion. METHODES: Nous avons obtenu du bureau de sante la liste des cas et les donnees de l’eclosion afin de decrire les cas chez les residents et le personnel, leur gravite et leur distribution dans le temps et a l’interieur de l’etablissement touche. Quand elles etaient disponibles, nous avons obtenu des donnees concernant les echantillons soumis au laboratoire de Sante publique Ontario et effectue un sequencage complet et une analyse phylogenetique des echantillons viraux de l’eclosion. RESULTATS: Sur les 65 residents de l’etablissement de soins de longue duree, 61 (94 %) ont contracte le SRAS-CoV-2, le taux de letalite etant de 45 % (28/61). Parmi les 67 employes initiaux, 34 (51 %) ont contracte le virus, et aucun n’est decede. Lorsque l’eclosion a ete declaree, 12 employes, 2 visiteurs et 9 residents presentaient des symptomes. Parmi les residents, les cas se trouvaient dans 3 des 4 secteurs de l’etablissement. L’analyse phylogenetique a montre une forte similitude des sequences; une seule autre souche de SRAS-CoV-2 genetiquement distincte a ete identifiee chez un employe a la troisieme semaine de l’eclosion. Apres le deploiement de toutes les mesures de gestion de l’eclosion, aucun cas n’a ete identifie parmi les 26 nouveaux employes appeles en renfort. INTERPRETATION: La propagation rapide et non detectee du virus dans un etablissement de soins de longue duree a donne lieu a des taux eleves d’infection chez les residents et le personnel. L’application progressive de mesures de gestion apres le pic de l’eclosion a permis d’eviter la contamination du personnel appele en renfort et fait desormais partie des politiques a long terme de prevention des eclosions en Ontario.

BACKGROUND: The implementation of outbreak management measures has decreased the frequency and severity of SARS-CoV-2 outbreaks in Ontario long-term care homes. We describe the epidemiological and laboratory data from one of the first such outbreaks in Ontario to assess factors associated with its severity, and the impact of progressive interventions for infection control over the course of the outbreak. METHODS: We obtained line list and outbreak data from the public health unit to describe resident and staff cases, severity and distribution of cases over time and within the outbreak facility. Where available, we obtained data on laboratory specimens from the Public Health Ontario Laboratory and performed whole genome sequencing and phylogenetic analysis of viral specimens from the outbreak. RESULTS: Among 65 residents of the long-term care home, 61 (94%) contracted SARS-CoV-2, with a case fatality rate of 45% (28/61). Among 67 initial staff, 34 (51%) contracted the virus and none died. When the outbreak was declared, 12 staff, 2 visitors and 9 residents had symptoms. Resident cases were located in 3 of 4 areas of the home. Phylogenetic analysis showed tight clustering of cases, with only 1 additional strain of genetically distinct SARS-CoV-2 identified from a staff case in the third week of the outbreak. No cases were identified among 26 new staff brought into the home after full outbreak measures were implemented. INTERPRETATION: Rapid and undetected viral spread in a long-term care home led to high rates of infection among residents and staff. Progressive implementation of outbreak measures after the peak of cases prevented subsequent staff cases and are now part of long-term care outbreak policy in Ontario.

A clinical prediction rule can be used to predict asymptomatic chlamydia/gonorrhea infections among women and heterosexual men using an Internet-based testing service in British Columbia, Canada (GetCheckedOnline.com). Supplemental digital content is available in the text., Background Clinical prediction rules (CPRs) can be used in sexually transmitted infection (STI) testing environments to prioritize individuals at the highest risk of infection and optimize resource allocation. We previously derived a CPR to predict asymptomatic chlamydia and/or gonorrhea (CT/NG) infection among women and heterosexual men at in-person STI clinics based on 5 predictors. Population differences between clinic-based and Internet-based testers may limit the tool's application across settings. The primary objective of this study was to assess the validity, sensitivity, and overall performance of this CPR within an Internet-based testing environment (GetCheckedOnline.com). Methods We analyzed GetCheckedOnline online risk assessment and laboratory data from October 2015 to June 2019. We compared the STI clinic population used for CPR derivation (data previously published) and the GetCheckedOnline validation population using χ2 tests. Calibration and discrimination were assessed using the Hosmer-Lemeshow goodness-of-fit test and the area under the receiver operating curve, respectively. Sensitivity and the fraction of total screening tests offered were quantified for CPR-predicted risk scores. Results Asymptomatic CT/NG infection prevalence in the GetCheckedOnline population (n = 5478) was higher than in the STI clinic population (n = 10,437; 2.4% vs. 1.8%, P = 0.007). When applied to GetCheckedOnline, the CPR had reasonable calibration (Hosmer-Lemeshow, P = 0.90) and discrimination (area under the receiver operating characteristic, 0.64). By screening only individuals with total risk scores ≥4, we would detect 97% of infections and reduce screening by 14%. Conclusions The application of an existing CPR to detect asymptomatic CT/NG infection is valid within an Internet-based STI testing environment. Clinical prediction rules applied online can reduce unnecessary STI testing and optimize resource allocation within publicly funded health systems.

As of January 22, 2020, "disease caused by a novel coronavirus" became a reportable disease of public health significance in Ontario. Public health units were provided with guidance on the entry of patients tested for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus causing 2019 coronavirus disease (COVID-19), into the provincial public health information system. Between January 22 and February 22, 2020, there were 359 individuals who had a negative test result recorded and three confirmed cases of COVID-19. Of those who tested negative, 51% were female and 71% were under 50 years of age. The most common symptoms reported were cough (55%), fever (37%) and sore throat (35%). The majority were tested within three days of symptom onset, but over one-quarter tested more than seven days after symptom onset. Over the first month of reportability, reported travel history shifted from China to an increasing proportion with travel outside of China.

Depuis le 22 janvier 2020, la « maladie causée par un nouveau coronavirus » est devenue une maladie à déclaration obligatoire d’importance pour la santé publique en Ontario. Les bureaux de santé publique ont reçu des directives sur la saisie des patients testés pour le coronavirus responsable du syndrome respiratoire aigu sévère (SRAS-CoV-2), le virus causant la maladie à coronavirus 2019 (COVID-19), dans le système provincial d’information sur la santé publique. Entre le 22 janvier et le 22 février 2020, 359 personnes ont reçu un résultat négatif de test et trois cas de COVID-19 ont été confirmés. Parmi les personnes dont le résultat était négatif, 51 % étaient des femmes et 71 % avaient moins de 50 ans. Les symptômes les plus fréquemment signalés étaient la toux (55 %), la fièvre (37 %) et le mal de gorge (35 %). La majorité des personnes ont été testées dans les trois jours suivant l’apparition des symptômes, mais plus d’un quart d’entre elles l’ont été plus de sept jours après. Durant le premier mois de déclaration, les antécédents de voyage déclarés ont passé de la Chine à une proportion croissante de voyages ailleurs qu’en Chine.

Setting Syndemics occur when two or more health conditions interact to increase morbidity and mortality and are exacerbated by social, economic, environmental, and political factors. Routine provincial surveillance in Ontario assesses and reports on the epidemiology of single infectious diseases separately. Therefore, we aimed to develop a method that allows disease overlaps to be examined routinely as a path to better understanding and addressing syndemics in Ontario. Intervention We extracted data for individuals with a record of chlamydia, gonorrhea, infectious syphilis, hepatitis B and C, HIV/AIDS, invasive group A streptococcal disease (iGAS), or tuberculosis in Ontario’s reportable disease database from 1990 to 2018. We transformed the data into a person-based integrated surveillance dataset retaining individuals (clients) with at least one record between 2006 and 2018. Outcomes The resulting dataset had 659,136 unique disease records among 470,673 unique clients. Of those clients, 23.1% had multiple disease records with 50 being the most for one client. We described the frequency of disease overlaps; for example, 34.7% of clients with a syphilis record had a gonorrhea record. We quantified known overlaps, finding 1274 clients had gonorrhea, infectious syphilis, and HIV/AIDS records, and potentially emerging overlaps, finding 59 clients had HIV/AIDS, hepatitis C, and iGAS records. Implications Our novel person-based integrated surveillance dataset represents a platform for ongoing in-depth assessment of disease overlaps such as the relative timing of disease records. It enables a more client-focused approach, is a step towards improved characterization of syndemics in Ontario, and could inform other jurisdictions interested in adopting similar approaches.

ObjectivesThe objective of our study was to estimate the rate of workplace outbreak-associated cases of COVID-19 by industry in labour market participants aged 15-69 years who reported working the majority of hours outside the home in Ontario, Canada.MethodsWe conducted a population based cross-sectional study of COVID-19 workplace outbreaks and associated-cases reported in Ontario between April 1, 2020 and March 31, 2021. All outbreaks were manually classified into two digit North American Industry Classification System (NAICS) codes. We obtained denominator data from the Statistics Canada Labour Force Survey in order to estimate the incidence of outbreak-associated cases per 100,000,000 hours amongst individuals who reported the majority of hours were worked outside the home. We performed this analysis across industries and in three distinct time periods.ResultsOverall, 12% of cases were attributed to workplace outbreaks among working age adults across our study period. While incidence varied across the time periods, the five industries with the highest incidence rates across our study period were agriculture; healthcare and social assistance; food manufacturing; educational services; and, transportation and warehousing.ConclusionsCertain industries have consistently increased incidence of COVID-19 over the course of the pandemic. These results may assist in ongoing efforts to reduce transmission of COVID-19, by prioritizing resources, as well as industry-specific guidance, vaccination, and public health messaging.

We compared secondary attack rates in households with B.1.1.7 variant of concern (VOC) versus non-VOC index cases in a matched cohort in Ontario, Canada. The secondary attack rate for VOC index cases was 1.31 times higher than non-VOC index cases. This increase was particularly accentuated for asymptomatic or presymptomatic index cases.

Supplemental Digital Content is available in the text, Objective: To analyze workplace outbreaks by industry sector in the first wave of the pandemic, and associated household cases. Methods: Number, size, and duration of outbreaks were described by sector, and outbreak cases were compared to sporadic cases in the same time frame. Address matching identified household cases with onset ≥2 days before, ≥2 days after, or within 1 day of the workplace outbreak case. Results: There were 199 outbreaks with 1245 cases, and 68% of outbreaks and 80% of cases belonged to (1) Manufacturing, (2) Agriculture, Forestry, Fishing, Hunting, (3) Transportation and Warehousing. There were 608 household cases associated with 339 (31%) outbreak cases, increasing the burden of illness by 56%. Conclusions: Workplace outbreaks primarily occurred in three sectors. Prevention measures should target industry sectors at risk to prevent spread in and out of the workplace.

IMPORTANCEHigher secondary attack rates related to variant of concern (VOC) index cases have been reported, but have not been explored within households, which continue to be an important source of coronavirus disease 2019 (COVID-19) transmissionOBJECTIVETo compare secondary attack rates in households with VOC versus non-VOC index cases.DESIGNA retrospective cohort study of household index cases reported from February 7 – 27, 2021. A propensity-score matched cohort was derived to calculate adjusted estimates.SETTINGOntario, Canada.PARTICIPANTSA population-based cohort of all private households with index cases. We excluded cases in congregate settings, as well as households with one individual or with >1 case with the same earliest symptom onset date.EXPOSUREVOC status, defined as either individuals confirmed as B.1.1.7 using whole genome sequencing or those that screened positive for the N501Y mutation using real-time PCR.MAIN OUTCOME AND MEASUREHousehold secondary attack rate, defined as the number of household secondary cases that occurred 1-14 days after the index case divided by the total number of household secondary contacts.RESULTSWe included 1,259 index VOC and non-VOC cases in the propensity score-matched analysis. The secondary attack rate for VOC index cases in this matched cohort was 1.31 times higher than non-VOC index cases (RR=1.31, 95%CI 1.14-1.49), similar to the unadjusted estimate. In stratified analyses, the higher secondary attack rate for VOC compared to non-VOC index cases was accentuated for asymptomatic index cases (RR=1.91, 95% CI 0.96-3.80) and presymptomatic cases (RR=3.41, 95%CI 1.13-10.26)CONCLUSIONS AND RELEVANCEThis study provides strong evidence of increased transmissibility in households due to VOCs and suggests that asymptomatic and pre-symptomatic transmission may be of particular importance for VOCs. Our study suggests that more aggressive public health measures will be needed to control VOCs and that ongoing research is needed to understand mechanisms of VOC transmissibility to curb their associated morbidity and mortality.

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

BackgroundPerformance characteristics of SARS-CoV-2 nucleic acid detection assays are understudied within contexts of low pre-test probability, including screening asymptomatic persons without epidemiological links to confirmed cases, or asymptomatic surveillance testing. SARS-CoV-2 detection without symptoms may represent resolved infection with persistent RNA shedding, presymptomatic or asymptomatic infection, or a false positive test. This study assessed clinical specificity of SARS-CoV-2 real-time reverse transcription polymerase chain reaction (rRT-PCR) assays by retesting positive specimens from five pre-test probability groups ranging from high to low with an alternate assay.Materials and MethodsA total of 122 rRT-PCR positive specimens collected from unique patients between March and July 2020 were retested using a laboratory-developed nested RT-PCR assay targeting the RNA-dependent RNA polymerase (RdRp) gene followed by Sanger sequencing.ResultsSignificantly less positive results in the lowest pre-test probability group (facilities with institution-wide screening having ≤ 3 positive asymptomatic cases) were reproduced with the nested RdRp gene RT-PCR assay than in all other groups combined (5/32, 15·6% vs 61/90, 68%; p ConclusionsA higher proportion of false-positive test results are likely with lower pre-test probability. Positive SARS-CoV-2 PCR results should be interpreted within the context of patient history, clinical setting, known exposure, and estimated community disease prevalence. Large-scale SARS-CoV-2 screening testing initiatives among low pre-test probability populations should be evaluated thoroughly prior to implementation given the risk of false positives and consequent potential for harm at the individual and population level.

Le seuil d’immunite collective est la proportion minimum de la population qui doit etre immunisee contre une maladie infectieuse, habituellement par le biais de la vaccination, pour que l’incidence de la maladie reste stable ou diminue[1][1]. Le seuil d’immunite collective pour la

Accurate SARS-CoV-2 diagnosis is essential to guide prevention and control of COVID-19. Here we examine SARS-CoV-2 molecular-based test performance characteristics and summarize case-level data related to COVID-19 diagnosis. From January 11 through April 22, 2020, Public Health Ontario conducted SARS-CoV-2 testing of 86,942 specimens collected from 80,354 individuals, primarily using real-time reverse-transcription polymerase chain reaction (rRT-PCR) methods. We analyzed test results across specimen types and for individuals with multiple same-day and multi-day collected specimens. Nasopharyngeal compared to throat swabs had a higher positivity (8.8% vs. 4.8%) and an adjusted estimate 2.9 Ct lower (SE = 0.5, pt of multi-day specimens increased over time. Symptomatic cases had rRT-PCR results with an adjusted estimate 3.0 Ct (SE = 0.5, p

IntroductionWorkplaces requiring in-person attendance of employees for ongoing operations may be susceptible to SARS-CoV-2 outbreaks that impact workers as well as their close contacts. To understand industry sectors impacted by workplace outbreaks in the first wave of the pandemic, and the additional burden of illness through household transmission, we analyzed public health declared workplace outbreaks between January 21 to June 30, 2020, and their associated cases from January 21 to July 28.MethodsNumber, size and duration of outbreaks were described by sector, and outbreak cases were compared to sporadic cases in the same time frame. Address matching identified household cases with onset ≥2 days before, ≥2 days after, or within 1 day of the workplace outbreak case.ResultsThere were 199 outbreaks with 1245 cases, and 68% of outbreaks and 80% of cases belonged to i) Manufacturing, ii) Agriculture, Forestry, Fishing, Hunting, iii) Transportation and Warehousing. Median size of outbreaks was 3 cases (range: 1-140), and lasted median 7days (range: 0-119). Outbreak cases were significantly more likely to be male, younger, healthier, and have better outcomes. There were 608 household cases associated with 339 (31%) outbreak cases with valid addresses, increasing the burden of illness by 56%. The majority of household cases (368, 60%) occurred after the outbreak case.ConclusionsWorkplace outbreaks primarily occurred in three sectors. COVID-19 prevention measures should target industry sectors at risk by preventing introduction from exposed employees, spread in the workplace, and spread outside of the workplace.What is already known about this topic?COVID-19 outbreaks occur within workplaces and can spread to the communityWhat is added by this report?From January 21 – June 30, 2020, there were 199 workplace outbreaks in Ontario, Canada; 68% of outbreaks and 80% of outbreak-associated COVID-19 case were in three industry sectors: Manufacturing, Agriculture/Forestry/Fishing/Hunting, and Transportation/Warehousing. Household transmission occurred among 31% of outbreak cases, resulting in a 56% increase in workplace outbreak-associated cases when burden of household transmission is considered.What are the implications for public health practice?Workplace outbreak prevention measures should be targeted to industry sectors at risk by preventing introduction from exposed employees, spread in the workplace, and transmission to the greater community.

Influenza vaccine effectiveness against influenza and noninfluenza respiratory viruses (NIRVs) was assessed by test-negative design using historic datasets of the community-based Canadian Sentinel Practitioner Surveillance Network, spanning 2010–2011 to 2016–2017. Vaccine significantly reduced the risk of influenza illness by >40% with no effect on coronaviruses or other NIRV risk.

Interim results from Canada's Sentinel Practitioner Surveillance Network show that during a season characterised by early co-circulation of influenza A and B viruses, the 2019/20 influenza vaccine has provided substantial protection against medically-attended influenza illness. Adjusted VE overall was 58% (95% confidence interval (CI): 47 to 66): 44% (95% CI: 26 to 58) for A(H1N1)pdm09, 62% (95% CI: 37 to 77) for A(H3N2) and 69% (95% CI: 57 to 77) for influenza B viruses, predominantly B/Victoria lineage.

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.

Background Understanding differences in HIV incidence among people living with hepatitis C virus (HCV) can help inform strategies to prevent HIV infection. We estimated the time to HIV diagnosis among HCV-positive individuals and evaluated factors that could affect HIV-infection risk in this population. Patients and methods The British Columbia Hepatitis Testers Cohort includes all BC residents (~1.5 million: about a third of all residents) tested for HCV and HIV from 1990 to 2013 and is linked to administrative health care and mortality data. All HCV-positive and HIV-negative individuals were followed to measure time to HIV acquisition (positive test) and identify factors associated with HIV acquisition. Adjusted HRs (aHRs) were estimated using Cox proportional-hazard regression. Results Of 36,077 HCV-positive individuals, 2,169 (6%) acquired HIV over 266,883 years of follow-up (overall incidence of 8.1 per 1,000 person years). Overall median (IQR) time to HIV infection was 3.87 (6.06) years. In Cox regression, injection-drug use (aHR 1.47, 95% CI 1.33–1.63), HBV infection (aHR 1.34, 95% CI 1.16–1.55), and being a man who has sex with men (aHR 2.78, 95% CI 2.14–3.61) were associated with higher risk of HIV infection. Opioid-substitution therapy (OST) (aHR 0.59, 95% CI 0.52–0.67) and mental health counseling (aHR 0.48, 95% CI 0.43–0.53) were associated with lower risk of HIV infection. Conclusion Injection-drug use, HBV coinfection, and being a man who has sex with men were associated with increased HIV risk and engagement in OST and mental health counseling were associated with reduced HIV risk among HCV-positive individuals. Improving access to OST and mental health services could prevent transmission of HIV and other blood-borne infections, especially in settings where access is limited., Video abstract

Introduction The Canadian Sentinel Practitioner Surveillance Network reports vaccine effectiveness (VE) for the 2018/19 influenza A(H3N2) epidemic. Aim To explain a paradoxical signal of increased clade 3C.3a risk among 35–54-year-old vaccinees, we hypothesise childhood immunological imprinting and a cohort effect following the 1968 influenza A(H3N2) pandemic. Methods We assessed VE by test-negative design for influenza A(H3N2) overall and for co-circulating clades 3C.2a1b and 3C.3a. VE variation by age in 2018/19 was compared with amino acid variation in the haemagglutinin glycoprotein by year since 1968. Results Influenza A(H3N2) VE was 17% (95% CI: −13 to 39) overall: 27% (95% CI: −7 to 50) for 3C.2a1b and −32% (95% CI: −119 to 21) for 3C.3a. Among 20–64-year-olds, VE was −7% (95% CI: −56 to 26): 6% (95% CI: −49 to 41) for 3C.2a1b and −96% (95% CI: −277 to −2) for 3C.3a. Clade 3C.3a VE showed a pronounced negative dip among 35–54-year-olds in whom the odds of medically attended illness were > 4-fold increased for vaccinated vs unvaccinated participants (p Discussion Imprinting by the first childhood influenza infection is known to confer long-lasting immunity focused toward priming epitopes. Our findings suggest vaccine mismatch may negatively interact with imprinted immunity. The immunological mechanisms for imprint-regulated effect of vaccine (I-REV) warrant investigation.

Background There is mounting evidence that the recent resurgence of pertussis in many countries is in part related to the acellular vaccine, which has been administered in Canada since 1997. This vaccine elicits a different cell-mediated immune response than the previously used whole-cell vaccine, and its effectiveness wanes over time. The aim of this study is to understand the immunological, demographic and clinical factors that mediate protection from pertussis on exposure. Methods This is a household case-control study protocol. Following notification of an index case in a household, a study team will conduct a home visit to collect data and biological specimens. The study team will return to the household 8 weeks from the onset of illness in the index case. The Th1, Th2 and Th17 responses, cytokine expression, IgG subclass, blood cell counts and presence of Bordetella pertussis will be determined. We will use laboratory and statistical analyses to determine immunological differences between contacts who are infected with B. pertussis and contacts who remain healthy, and to determine which clinical and demographic covariates are associated with a reduced risk of infection. Interpretation The results of this study will be essential for understanding the immune response required for protection from infection with B. pertussis and will contribute to our understanding of the shortcomings of the current vaccine.

The herd immunity threshold is the minimum proportion of the population that must be immune to an infectious disease, usually due to vaccination, for the incidence of the disease to remain stable or decrease.[1][1] The herd immunity threshold for measles, one of the most infectious diseases, is

Intramuscular Immune Serum Globulin (IM ISG) is recommended as post-measles exposure prophylaxis (PEP) when administered within 6days of initial exposure, with variable effectiveness in preventing measles disease. Effectiveness of IM ISG PEP in preventing clinical measles was assessed during a 2014 measles outbreak among a religious-affiliated community in British Columbia, Canada.Fifty-five self-reporting measles susceptible contacts were offered exclusively IM ISG PEP within an eligibility period best surmised to be within 6days of initial measles case exposure. Clinical outcome of IM ISG PEP recipients was determined by selective active surveillance and case self-reporting. IM ISG PEP failure was defined as onset of a measles-like rash 8-21days post-IM ISG PEP. Post-IM ISG PEP measles IgG antibody level was tested in 8 recipients. Factors associated with measles disease were analyzed.Seventeen of 55 IM ISG PEP recipients developed clinically consistent measles in the following 8-21days, corresponding to an estimated crude protective effectiveness of 69%. In school aged children 5-18years, among whom potential exposure intensity and immune status confounders were considered less likely, estimated IM ISG PEP protective effectiveness was 50%. Age25years was significantly associated with breakthrough clinical measles in bivariate analysis (p=0.0217). Among 8 tested contacts of 17 considered IM ISG PEP failures, post-IM ISG PEP measles IgG antibody levels (mean 16.3days (range 16-17days) post-PEP) were all150mIU/ml.The estimated crude IM ISG PEP protective effectiveness against measles disease within 8-21days post-ISG administration was 69%. Accuracy of this estimated protective effectiveness is vulnerable to assumptions and uncertainties in ascertaining exposure details and pre-exposure immune status. Increasing the Canadian recommended measles IM ISG PEP dose from 0.25 to 0.5ml/kg (up to 15ml maximum volume) may increase protective effectiveness.

OBJECTIVES: The objectives of the study were to 1) describe the implementation of the “Testing is Healthy” campaign in four locations in British Columbia (BC) and 2) report process evaluation indicators for the campaign. PARTICIPANTS: Young adults ages 20–29 years, the age group with the highest reported rates of chlamydia and gonorrhea in BC. SETTINGS: Movie theatres located in Langley, Burnaby, Coquitlam and Surrey, which are communities served by the Fraser Health Authority (FHA) in BC. INTERVENTION: The FHA launched the campaign in 2014 and 2015 to bring down the prevalence of sexually transmitted infections (STIs) and HIV in the region. The campaign used the Cineplex TimePlay platform to engage moviegoers in answering STI/HIV-related questions, and to connect them to a clinic finder on the BC Centre for Disease Control Sex Smart Resource (SSR) website. TimePlay includes elements of gaming, is technology-based, and has been a successful advertisement platform for consumer products and services. However, this is the first time it has been used for sexual health promotion. The campaign was evaluated for 1) reach, based on theatre attendance and TimePlay participation, and 2) the effectiveness of connecting people to sexual health information using SSR web analytics. OUTCOMES: In total, the campaign received 548 410 views and 77 149 plays. SSR web analytics showed a significant increase in unique page views of the Clinic Finder page between the first and the second campaign. IMPLICATIONS: The campaign reached a large population at a low cost and was correlated with spikes in the unique page views for the Clinic Finder page.

Timely surveillance of enteric diseases is necessary to identify and control cases and outbreaks. Our objective was to evaluate the timeliness of enteric disease surveillance in British Columbia, Canada, compare these results to other settings, and recommend improvements. In 2012 and 2013, information was collected from case report forms and laboratory information systems on 2615Salmonella, shigatoxin-producingE. coli,Shigella, andListeriainfections. Twelve date variables representing the surveillance process from onset of symptoms to case interview and final laboratory results were collected, and intervals were measured. The median time from onset of symptoms to reporting subtyping results to BC epidemiologists was 26–36 days and from onset of symptoms to case interview was 12–14 days. Our findings were comparable to the international literature except for a longer time (up to 29 day difference) to reporting of PFGE results to epidemiologists in BC. Such a delay may impact our ability to identify and solve outbreaks. Several process and system changes were implemented which should improve the timeliness of enteric disease surveillance.