[Show abstract][Hide abstract] ABSTRACT: In 2011 the largest measles outbreak in North America in a decade occurred in Quebec, Canada with over 700 cases. In contrast, measles activity in neighbouring province Ontario remained low (8 cases). Our objective was to determine the extent to which the difference could be explained by differing travel patterns.
We explored the relationship between measles cases over 2007-2011, by importation classification, in Quebec and Ontario in relation to global travel patterns to each province using an ecological approach. Global measles exposure was estimated by multiplying the monthly traveler volume for each country of origin into Quebec or Ontario by the yearly measles incidence rate for the corresponding country. Visual inspection of temporal figures and calculation of Pearson correlation coefficients were performed.
Global measles exposure was similar in Ontario and Quebec. In Quebec, there was a nearly perfectly linear relationship between annual measles cases and its global measles exposure index over 2007-2011 (r = 0.99, p = 0.001). In contrast, there was a non-significant association in Ontario. The 2011 rise in Quebec's index was largely driven by a dramatic increase in measles activity in France the same year.
Global measles activity was associated with measles epidemiology in Quebec. Global measles exposure risk is higher in Ontario than Quebec. Differences in measles epidemiology between Ontario and Quebec from 2007-2011 are not explained by greater exposure in Quebec. A combination of alternative factors may be responsible, including differences in population susceptibility.
[Show abstract][Hide abstract] ABSTRACT: Background:
In Ontario, Canada, we conducted an evaluation of rotavirus (RV) vaccine on hospitalizations and Emergency Department (ED) visitations for acute gastroenteritis (AGE). In our original analysis, any one of the International Classification of Disease, Version 10 (ICD-10) codes was used for outcome ascertainment: RV-specific- (A08.0), viral- (A08.3, A08. 4, A08.5), and unspecified infectious- gastroenteritis (A09). Annual age-specific rates per 10,000 population were calculated.
The average monthly rate of AGE hospitalization for children under age two increased from 0.82 per 10,000 from January 2003 to March 2009, to 2.35 over the period of April 2009 to March 31, 2013. Similar trends were found for ED consultations and in other age groups. A rise in events corresponding to the A09 code was found when the outcome definition was disaggregated by ICD-10 code. Documentation obtained from the World Health Organization confirmed that a change in directive for the classification of unspecified gastroenteritis occurred with the release of ICD-10 in April 2009. AGE events previously classified under the code K52.9, are now classified under code A09.9.
Based on change in the classification of unspecified gastroenteritis we modified our outcome definition to also include unspecified non-infectious-gastroenteritis (K52.9). We recommend other investigators consider using both A09.9 and K52.9 ICD-10 codes for outcome ascertainment in future rotavirus vaccine impact studies to ensure that all unspecified cases of AGE are captured, especially if the study period spans 2009.
BMC Research Notes 09/2015; 8:439. DOI:10.1186/s13104-015-1412-5
[Show abstract][Hide abstract] ABSTRACT: Bordetella pertussis testing performed using real-time polymerase chain reaction (RT-PCR) is interpreted based on a cycle threshold (Ct) value. At Public Health Ontario Laboratories (PHOL), a Ct value <36 is reported as positive, and Ct values ≥36 and <40 are reported as indeterminate. PHOL reported indeterminate results to physicians and public health units until May 2012, after which these results were only reported to physicians. We investigated the association between Ct value and disease symptom and severity to examine the significance of indeterminate results clinically, epidemiologically and for public health reporting. B. pertussis positive and indeterminate RT-PCR results were linked to pertussis cases reported in the provincial Integrated Public Health Information System (iPHIS), using deterministic linkage. Patients with positive RT-PCR results had a lower median age of 10.8 years compared to 12.0 years for patients with indeterminate results (p = 0.24). Hospitalized patients had significantly lower Ct values than non-hospitalized patients (median Ct values of 20.7 vs. 31.6, p<0.001). The proportion of patients reporting the most indicative symptoms of pertussis did not differ between patients with positive vs. indeterminate RT-PCR results. Taking the most indicative symptoms of pertussis as the gold-standard, the positive predictive value of the RT-PCR test was 68.1%. RT-PCR test results should be interpreted in the context of the clinical symptoms, age, vaccination status, prevalence, and other factors. Further information on interpretation of indeterminate RT-PCR results may be needed, and the utility of reporting to public health practitioners should be re-evaluated.
PLoS ONE 07/2015; 10(7):e0133209. DOI:10.1371/journal.pone.0133209 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine if reductions in medically-attended pediatric varicella and herpes zoster occurred in Ontario, Canada, after publicly-funded varicella immunization was implemented in 2004.
For fiscal years (FY) 1992-2011, we examined data on varicella and herpes zoster physician office visits, emergency department (ED) visits, hospitalizations (including for varicella-associated skin and soft tissue infections [SSTI]), and intensive care unit (ICU) admissions, among those aged <18 years. The pre-vaccine, privately-available, and vaccine program eras were FY1992-1998, FY1999-2003, and FY2004-2011, respectively. We used Poisson regressionand Kruskal-Wallis tests (all at the p<0.05 level of significance), and compared rates using incidence rate ratios (IRRs) and 95% confidence intervals (CIs).
Incidence of varicella office visits declined over the study period from a high of 25.1/1,000 in FY1994 to a low of 3.2/1,000 in FY2011. ED visits and hospitalizations followed similar patterns of decreasing rates later in the study period. IRRs comparing the vaccine program versus pre-vaccine eras were 0.29 (95%CI: 0.26-0.32) for office visits, 0.29 (95%CI: 0.21-0.40) for ED visits, and 0.41 (95%CI: 0.10-1.69) for hospitalizations. Annual declines in varicella office visits were 7.7%, 9.1%, 8.4%, and 8.4% per year among children aged <1 year, 1-4 years, 5-11 years, and ≥12 years, respectively (all p<0.001). Age-specific rates of varicella-associated SSTI declined significantly among children <12 years (p<0.001) and rates of ICU admissions decreased significantly for children <1 year (p = 0.02). (p<0.001) over the study period. For children aged 5-17 years, herpes zoster office visits decreased whereas ED visits increased (both p<0.001) and there was a small, non-significant (p = 0.07), decrease in hospitalizations.
Medically-attended varicella decreased during the study period, particularly since varicella vaccine was publicly-funded. Results suggest immunization program-related changes in varicella epidemiology, including herd effects, demonstrated by reductions in varicella in program-ineligible age groups. We did not observe a consistent impact on herpes zoster.
PLoS ONE 07/2015; 10(7):e0129483. DOI:10.1371/journal.pone.0129483 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ontario has a single payer provincial health insurance program. Administrative data may provide a potentially robust source of information for post-marketing vaccine studies. Vaccine-specific immunization billing codes were introduced in 2011. Our objective was to validate Ontario's universal health care administrative datasets to assess infant immunization status. Electronic medical record data from the Electronic Medical Record Administrative data Linked Database (EMRALD) was used as the reference standard to calculate performance characteristics of the Ontario Health Insurance Plan (OHIP) database vaccine-specific and general immunization codes for four primary infant immunizations: diphtheria, tetanus, acellular pertussis, inactivated polio, Haemophilus influenzae type B (DTaP-IPV-Hib) combination vaccine, pneumococcal conjugate vaccine, measles, mumps, rubella (MMR) vaccine, and meningococcal conjugate serogroup C vaccine. OHIP billing claims had specificity ranging from 81% to 92%, sensitivity 70%-83%, positive predictive value (PPV) 97%-99%, and negative predictive value (NPV) 13-46% for identifying the various specific vaccines in administrative data. For cohorts vaccinated in the new code introduction phase, using both the vaccine-specific and general codes had higher sensitivity than the vaccine-specific codes alone. In conclusion, immunization billing claims from administrative data in Ontario had high specificity and PPV, moderate sensitivity, and low NPV. This study identifies some of the applications of utilizing administrative data for post-marketing vaccine studies. However, limitations of these data decrease their utility for measuring vaccine coverage and effectiveness. Therefore, the establishment of a comprehensive and linkable immunization registry should be a provincial priority.
[Show abstract][Hide abstract] ABSTRACT: Given the variation in human papillomavirus (HPV) vaccine coverage across Canada, and debate regarding delivery of HPV vaccines in Catholic schools, we studied online comments on Canadian news websites to understand public perceptions of HPV and HPV vaccine.
We searched English- and French-language Canadian news websites for 2012 articles that contained the terms "HPV" or "human papillomavirus." Articles about HPV vaccinations that contained at least one comment were included. Two researchers independently coded comments, analyzing them for emerging themes.
We identified 3073 comments from 1198 individuals in response to 71 news articles; 630 (52.6%) individuals expressed positive sentiments about HPV vaccination (2.5 comments/individual), 404 (33.7%) were negative (3.0 comments/individual), 34 (2.8%) were mixed (1.5 comments/individual) and 130 (10.8%) were neutral (1.6 comments/individual). Vaccine-supportive commenters believed the vaccine is safe and effective. Common themes in negative comments included concerns regarding HPV vaccine safety and efficacy, distrust of pharmaceutical companies and government, and belief that school-age children are too young for HPV vaccine. Many comments focused on whether the Catholic Church has the right to inform health policy for students, and discussion often evolved into debates regarding HPV and sexual behaviour. We noted that many individuals doubted the credibility of vaccine safety information.
The majority of commenters do not appear to be against HPV vaccination, but public health messaging that focuses on both the vaccine's safety profile, and its use as a means to prevent cancer rather than sexually transmitted HPV infection may facilitate its acceptance.
PLoS ONE 06/2015; 10(6):e0129587. DOI:10.1371/journal.pone.0129587 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sub-optimal vaccination coverage and recent outbreaks of vaccine-preventable diseases serve as a reminder that vaccine hesitancy remains a concern. ImmunizeCA, a new smartphone app to help track immunizations, may address several reasons for not vaccinating. We conducted a study to describe demographic variables, attitudes, beliefs and information sources regarding pediatric vaccination in a sample of childbearing women who were willing to download an immunization app. We also sought to measure their current mobile usage behaviours and determine if there is an association between participant demographics, attitudes, beliefs and information sources regarding pediatric vaccination and mobile usage. We recruited participants using a combination of passive and active methods at a tertiary care hospital in Ottawa, Canada. We used surveys to collect demographic information, examine attitudes, behaviour, and information sources regarding immunization and self-reported mobile phone usage. A total of 54 women participated. The majority had positive attitudes towards vaccination (96%) and intended to vaccinate their children (98%). Participants were interested in information on pediatric vaccination (94%), and found information from public health the most reliable and accessible (78%). Participants also trusted immunization information from their doctor or nurse and public health (83%) more than other sources. There was variability in participant use of mobile apps for other purposes. The median participant mobile readiness score was 3.2. We found no significant associations between participant age, behaviour and attitudes regarding vaccination and mobile readiness scores. This is the first evaluation of mobile readiness for a smartphone app to track immunizations. Our findings suggest that there exists an opportunity to provide reliable information on vaccination through mobile devices to better inform the public, however predictors of individual engagement with these technologies merits further study.
Human Vaccines and Immunotherapeutics 02/2015; 11(4). DOI:10.1080/21645515.2015.1009807 · 2.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It is unclear whether seasonal influenza vaccination results in a net increase or decrease in the risk for Guillain-Barré syndrome (GBS). To assess the effect of seasonal influenza vaccination on the absolute risk of acquiring GBS, we used simulation models and published estimates of age- and sex-specific risks for GBS, influenza incidence, and vaccine effectiveness. For a hypothetical 45-year-old woman and 75-year-old man, excess GBS risk for influenza vaccination versus no vaccination was -0.36/1 million vaccinations (95% credible interval -1.22 to 0.28) and -0.42/1 million vaccinations (95% credible interval, -3.68 to 2.44), respectively. These numbers represent a small absolute reduction in GBS risk with vaccination. Under typical conditions (e.g. influenza incidence rates >5% and vaccine effectiveness >60%), vaccination reduced GBS risk. These findings should strengthen confidence in the safety of influenza vaccine and allow health professionals to better put GBS risk in context when discussing influenza vaccination with patients.
[Show abstract][Hide abstract] ABSTRACT: Controversy about the evidence, economics, ethics, lobbying, and decision making surrounding a new vaccine for serogroup B meningococcal disease should trigger change in the way we develop recommendations for new vaccines say Natasha Crowcroft and colleagues
[Show abstract][Hide abstract] ABSTRACT: Purpose: To estimate incidence-based healthcare costs attributable to invasive meningococcal disease (IMD) for acute illness and long-term sequelae.
Method: We conducted a retrospective matched cohort study using individually linked laboratory and health administrative data covering the Ontario, Canada, population (~13 million) to estimate healthcare costs attributable to IMD.
Subjects with IMD (“exposed” in the cohort study) were identified in the Public Health Ontario Laboratory (PHOL) dataset and individually linked to health administrative data. Unexposed subjects, randomly drawn from the general population, were hard-matched to exposed subjects (5:1) on age, sex, income quartile, rural/urban residence, and co-morbidities.
Healthcare costs for acute illness and long-term sequelae were determined by employing the phase-of-care costing approach, organizing each subject’s observation time into 3 phases: acute infection (phase 1), continuing care (phase 2), and final, pre-death phase (phase 3). Phase length was determined using the joinpoint approach and graphing costs. Costs were standardized to 10-day costs per phase (2012 Canadian dollars).
Result: From 2000 to 2010, we identified 582 subjects with IMD in the PHOL dataset and were able to link 469 to the administrative data. Exposed subjects had a mean age of 30.5 years (±26.2), 49.7% were female, 21.3% had any sequelae (85% of those had at least 1 major sequelae), 93% were hospitalized (mean length of stay 11.8±14.7 days) and 30-day mortality was 9%. Mean follow-up was 5.8 years; phase 1 length was 18 days and phase 3 length 90 days.
Mean 10-day phase 1, 2 and 3 costs (95%CI) per exposed subject were $11,325 ($9,717-$13,078), $266 ($151-$423), and $23,196 ($18,300-$28,856), respectively. Mean 10-day phase 1, 2 and 3 costs per unexposed subject were $56 ($36-$82), $57 ($47-$68), and $9,615 ($6,929-$12,359), respectively. Mean 10-day phase 1, 2 and 3 attributable costs were $11,269 ($9,679-$13,017), $209 ($97-$370), and $13,694 ($9,126-$18,914), respectively. Attributable phase 1 costs were greater for those aged ≥25 years and those with sequelae. Attributable phase 2 costs were greater for those aged ≥45 years, females, and those with sequelae.
Conclusion: IMD is associated with increases in both acute and long-term healthcare costs compared with general population controls. High quality healthcare cost data attributable to IMD is important for healthcare planning and the evaluation of prevention strategies, including novel vaccines.
The 36th Annual Meeting of the Society for Medical Decision Making; 10/2014
[Show abstract][Hide abstract] ABSTRACT: Ontario, Canada, replaced the 4-6 year old diphtheria (D, d), tetanus (T), acellular pertussis (aP, ap) and polio (IPV) booster from DTaP-IPV to Tdap-IPV in May 2012. We assessed the impact of this replacement on the rate and types of reported adverse events following immunization (AEFIs). We used AEFIs reported among 4-6 years olds, through the provincial surveillance system, following administration of DTaP-IPV or Tdap-IPV from 2009 to 2013. Reporting rates per 100,000 doses distributed were calculated using publicly funded doses distributed as the denominator. A total of 204 AEFIs were reported (DTaP-IPV, n=182; Tdap-IPV, n=22). AEFI reporting rates were 33.1 and 6.3 per 100,000 doses distributed for DTaP-IPV and Tdap-IPV, respectively. Injection site reaction rate was lower for Tdap-IPV compared with DTaP-IPV (1.7 vs 20.6 per 100,000 doses). The replacement resulted in a decline in the number of reports and AEFI reporting rates, most notably a substantial decrease in injection site reactions.
[Show abstract][Hide abstract] ABSTRACT: Objective:
Invasive Neisseria meningitidis serogroup B (MenB) disease is a low incidence but severe infection (mean annual incidence 0.19/100,000/year, case fatality 11%, major long-term sequelae 10%) in Ontario, Canada. This study assesses the cost-effectiveness of a novel MenB vaccine from the Ontario healthcare payer perspective.
A Markov cohort model of invasive MenB disease based on high quality local data and data from the literature was developed. A 4-dose vaccination schedule, 97% coverage, 90% effectiveness, 66% strain coverage, 10-year duration of protection, and vaccine cost of C$75/dose were assumed. A hypothetical Ontario birth cohort (n=150,000) was simulated to estimate expected lifetime health outcomes, quality-adjusted life years (QALYs), and costs, discounted at 5%.
A MenB infant vaccination program is expected to prevent 4.6 invasive MenB disease cases over the lifetime of an Ontario birth cohort, equivalent to 10 QALYs gained. The estimated program cost of C$46.6 million per cohort (including C$318,383 for treatment of vaccine-associated adverse events) were not offset by healthcare cost savings of C$150,522 from preventing MenB cases, resulting in an incremental cost of C$4.76 million per QALY gained. Sensitivity analyses showed the findings to be robust.
An infant MenB vaccination program significantly exceeds commonly used cost-effectiveness thresholds and thus is unlikely to be considered economically attractive in Ontario and comparable jurisdictions.
[Show abstract][Hide abstract] ABSTRACT: The emergence of new digital technologies has 'disrupted' traditional vaccine information communication. This article reviews the impact of the Internet, social media, digital detection and mobile applications on both fueling anti-vaccine sentiment and providing a mechanism by which to address vaccine hesitancy. While the anti-vaccine community has leveraged the Internet and social media to bypass traditional sources of information and communicate with susceptible parents, digital surveillance and mobile apps offer an important opportunity for public health officials to develop new strategies to identify and address concerns in a real-time manner.
[Show abstract][Hide abstract] ABSTRACT: Evaluating the features and performance of health information systems can serve to strengthen the systems themselves as well as to guide other organizations in the process of designing and implementing surveillance tools. We adapted an evaluation framework in order to assess electronic immunization data collection systems, and applied it in two Ontario public health units.
The Centers for Disease Control and Prevention's Guidelines for Evaluating Public Health Surveillance Systems are broad in nature and serve as an organizational tool to guide the development of comprehensive evaluation materials. Based on these Guidelines, and informed by other evaluation resources and input from stakeholders in the public health community, we applied an evaluation framework to two examples of immunization data collection and examined several system attributes: simplicity, flexibility, data quality, timeliness, and acceptability. Data collection approaches included key informant interviews, logic and completeness assessments, client surveys, and on-site observations.
Both evaluated systems allow high-quality immunization data to be collected, analyzed, and applied in a rapid fashion. However, neither system is currently able to link to other providers' immunization data or provincial data sources, limiting the comprehensiveness of coverage assessments. We recommended that both organizations explore possibilities for external data linkage and collaborate with other jurisdictions to promote a provincial immunization repository or data sharing platform.
Electronic systems such as the ones described in this paper allow immunization data to be collected, analyzed, and applied in a rapid fashion, and represent the infostructure required to establish a population-based immunization registry, critical for comprehensively assessing vaccine coverage.
BMC Medical Informatics and Decision Making 01/2014; 14(1):5. DOI:10.1186/1472-6947-14-5 · 1.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In September 2007, a school-based human papillomavirus (HPV) vaccination program targeting grade 8 girls (approximately 13 years old) and delivered by public health was implemented in Ontario, Canada. We assessed reports of adverse events following immunization (AEFI) from the school-based program as part of quadrivalent HPV (HPV4) vaccine safety surveillance and to contribute to a comprehensive HPV vaccine program evaluation.
AEFIs following HPV4 vaccine (Gardasil(®)) administered between September 1, 2007 and December 31, 2011 were extracted from the province's reportable disease system. Confirmed AEFI reports among females 12-15 years old (i.e. assumed to have received vaccine through the program) were included. Events were grouped according to provincial AEFI case definitions. Rates were calculated using doses distributed as the denominator.
Between 2007 and 2011, 133 confirmed AEFIs were reported while 691,994 HPV4 vaccine doses were distributed in the school-based program. The overall reporting rate was 19.2 HPV4 AEFI per 100,000 doses distributed. Annual reporting rates decreased from 30.0 to 18.3 per 100,000 doses distributed. Frequently reported events included 'allergic reaction-dermatologic/mucosa' (25%), 'rash' (22%), and 'local/injection site reaction' (20%); 26% of reports had a non-specific event of 'other severe/unusual events' selected. Ten serious AEFIs were reported (7.5% of reports) including 2 anaphylaxis, 2 seizures, 1 thrombocytopenia and 1 death. Further review found that the reports of anaphylaxis did not meet the Brighton anaphylaxis definition and the death was attributed to a preexisting cardiac condition.
Overall these findings are consistent with the safety profile of HPV4 vaccine from pre-licensure clinical trials and post-marketing surveillance reports and importantly, no new safety signals were identified, especially no reports of VTE in this younger female population. Continued assessment of HPV4 AEFI surveillance data may be important to detect and investigate safety signals.