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Background The purpose of this paper is to systematically review the literature on the relationship between socioeconomic status (SES) and influenza immunization and to examine how certain measures of SES may influence interpretations of this relationship. Methods We conducted a systematic review of existing peer-reviewed literature to evaluate the above relationship in the general population. Electronic databases (MEDLINE and EMBASE) were searched from January 2012 to May 2017 to identify English-language studies relevant to this review. Studies were included where influenza vaccination was explicitly reported as the dependent variable and SES as the independent variable. We limited our review to measures of SES that focus on education, income, social class, occupation, and deprivation. Studies that measured SES using other variables (e.g., race, ethnicity, geographic location, rural or urban status, or insurance status) were excluded. Studies were also excluded if they did not report on the human population or did not analyze original data. The population of interest included all age groups, levels of health status, and sociodemographic backgrounds. The review was also limited to World Bank high-income countries. Two authors independently screened full-text articles after obtaining a Kappa score of K =  0.867. The methodological quality of manuscripts was assessed using the appraisal tools developed by the Joanna Briggs Institute. Results were qualitatively reported and synthesized. Results Of the 42 articles included in this review, 52.4% ( n  = 22) found that higher levels of SES resulted in higher levels of influenza vaccination; 4.5% ( n  = 2) reported a negative association; and 14.3% ( n  = 6) found no association. Just over a quarter (26.2%, n  = 12) of articles reported mixed results. Conclusions There was consistently a relationship between SES and influenza immunization, which varied according to how SES was measured. It is recommended that authors be explicit in defining the SES concept they are trying to capture and that they utilize multiple measures of SES (e.g., education, income, class).

The combination measles–mumps–rubella–varicella (MMRV) vaccine currently used in Canada (Priorix-Tetra) may increase the risk of febrile seizures relative to the separate vaccines (MMR and varicella) previously administered. We determined the risk of febrile seizure after the first dose of MMRV, as well as any additional risk for children at high risk for seizures because of pre-existing medical conditions. In this retrospective, population-based cohort study, we compared the risk of seizures after the first dose of MMRV with the risk after same-day administration of separate MMR and varicella vaccines (MMR+V) in children 12 to 23 months of age in the province of Alberta. We deterministically linked vaccination data to health service utilization data for seizures. We used Poisson regression, with adjustment for age and calendar year, to determine the risk for the full cohort and for high-risk children. The risk of seizures 7 to 10 days after vaccination was twice as high with MMRV as with MMR+V (relative risk [RR] 1.99, 95% confidence interval [CI] 1.30–3.05). The excess absolute risk of seizures was 3.52 seizures per 10 000 doses of MMRV relative to MMR+V. In high-risk children, the risk was not differentially higher for MMRV (RR 1.30, 95% CI 0.60–2.79). Despite an increased risk of febrile seizures following MMRV (compared with MMR+V), the absolute level of risk was small. Policy-makers need to balance these findings with the potential benefits of administering the combination vaccine or determine whether the choice of vaccine rests with clinicians and/or parents.

Background We describe the epidemiology of pertussis in Alberta, Canada by person, place, and time between 2004 and 2015, identify outbreak years, and examine vaccination coverage and vaccination timeliness. Methods We used health data from Alberta’s Communicable Disease Registry System for the period of January 1, 2004 through August 31, 2015 to identify unique cases of pertussis. Unique cases were deterministically linked to data in Alberta’s immunization repository and health care insurance plan registry. Population estimates and vaccination coverage were extracted from Alberta’s online Interactive Health Data Application. We estimated pertussis incidence rates per 100,000 persons by year, age group, gender, and health zone. Outbreak years were identified using a one-sided cumulative sum (CUSUM) analysis by comparing annual incidence rates to baseline rates. Results Over the period, 3510 cases of pertussis were confirmed by laboratory testing or epidemiological linkage. Incidence rates per 100,000 persons were highest in 2004 (20.5), 2005 (13.6), and 2015 (10.4) for all age groups. Incidence rates were highest among the youngest age groups and decreased as age groups increased. Based on CUSUM analysis, 2008 and 2012 met the criteria for outbreak years. Vaccination coverage was over 90% among the general population, however only 61% of cases received at least one dose. About 60% of cases were diagnosed 5+ years after receiving the vaccine. Approximately 87–91% of vaccinated cases did not receive the first three vaccine doses in a timely manner. Conclusion Pertussis incidence rates fluctuated over the period across all age groups. The majority of cases had no record of vaccination or were delayed in receiving vaccines. CUSUM analysis was an effective method for identifying outbreaks.

IntroductionThe appropriateness of using routinely collected laboratory data combined with administrative data for estimating influenza vaccine effectiveness (VE) is still being explored. This paper outlines a protocol to estimate influenza VE using linked laboratory and administrative data which could act as a companion to estimates derived from other methods.Methods and analysisWe will use the test-negative design to estimate VE for each influenza type/subtype and season. Province-wide individual-level records of positive and negative influenza tests at the Provincial Laboratory for Public Health in Alberta will be linked, by unique personal health numbers, to administrative databases and vaccination records held at the Ministry of Health in Alberta to determine covariates and influenza vaccination status, respectively. Covariates of interests include age, sex, immunocompromising chronic conditions and healthcare setting. Cases will be defined based on an individual’s first positive influenza test during the season, and potential controls will be defined based on an individual’s first negative influenza test during the season. One control for each case will be randomly selected based on the week the specimen was collected. We will estimate VE using multivariable logistic regression.Ethics and disseminationEthics approval was obtained from the University of Alberta’s Health Research Ethics Board—Health Panel under study ID Pro00075997. Results will be disseminated by public health officials in Alberta.

Background Rates of Bordetella pertussis have been increasing in Alberta, Canada despite vaccination programs. Waning immunity from existing acellular component vaccines may be contributing to this. Vaccine effectiveness can be estimated using a variety of data sources including diagnostic codes from physician billing claims, public health records, reportable disease and laboratory databases. We sought to determine if diagnostic codes from billing claims (administrative data) are adequately sensitive and specific to identify pertussis cases among patients who had undergone disease-specific laboratory testing. Methods Data were extracted for 2004–2014 from a public health communicable disease database that contained data on patients under investigation for B. pertussis (both those who had laboratory tests and those who were epidemiologically linked to laboratory-confirmed cases) in Alberta, Canada. These were deterministically linked using a unique lifetime person identifier to the provincial billing claims database, which contains International Classification of Disease version 9 (ICD-9) diagnostic codes for physician visits. We examined visits within 90 days of laboratory testing. ICD-9 codes 033 (whooping cough), 033.0 ( Bordetella pertussis ), 033.1 ( B. parapertussis ), 033.8 (whooping cough, other specified organism), and 033.9 (whooping cough, other unspecified organism) in any of the three diagnostic fields for a claim were classified as being pertussis-specific codes. We calculated sensitivity, specificity, positive (PPV) and negative (NPV) predictive values. Results We identified 22,883 unique patients under investigation for B. pertussis . Of these, 22,095 underwent laboratory testing. Among those who had a laboratory test, 2360 tested positive for pertussis. The sensitivity of a pertussis-specific ICD-9 code for identifying a laboratory-confirmed case was 38.6%, specificity was 76.9%, PPV was 16.0%, and NPV was 91.6%. Conclusion ICD-9 codes from physician billing claims data have low sensitivity and moderate specificity to identify laboratory-confirmed pertussis among persons tested for pertussis.

•Alberta implemented publicly funded chickenpox vaccination in 2002.•We examine shingles rates over 1994–2010.•Crude shingles rates increased over the period.•Among older persons the increasing rates of shingles began before vaccine licensure in 1998.•Shingles rates declined among the under 10s over 2002–2010. Purpose: A universal publicly funded chickenpox vaccination program was implemented in Alberta in 2002. We examine the epidemiology of medically attended shingles in Alberta from 1994 to 2010. Methods: Incident shingles cases (earliest health service utilizations for ICD-9 053 or ICD-10-CA B02) and their co-morbid conditions for the 12 months prior to shingles diagnosis were identified from the records of Alberta's universal, publicly funded health-care insurance system for 1994–2010. Shingles diagnostic codes at least 180 days after the first were classified as recurrent episodes. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Plan Registry. Annual age- and sex-specific rates were estimated. We estimated the proportion of all cases that were hospitalized. We explored the pattern of rates for sex, age-group co-morbidity and year effects and their interactions. Results: Crude rates of shingles increased over the interval 1994–2010. Most persons had only a single episode of shingles; 4% of cases were hospitalized. Shingles rates were higher among females than males. While only 2% of shingles cases had one or more co-morbidities, this proportion was also higher for females than males. Prior to 2002, all age groups of both sexes experienced increasing annual rates of shingles. However, there was a sharp decline in the rate of shingles for both females and males under the age of 10 years for 2002–2010, the period in which there was publicly funded chickenpox vaccination. Conclusion: The declining rates of shingles among persons under the age of 10 years are consistent with an impact of the chickenpox vaccination program. The trend of increasing rates of shingles among older persons began prior to implementation of vaccination.

•Children not-completely vaccinated are a heterogeneous group.•Many lifestyle factors impact vaccine completion.•Multiple household moves and >3 children are linked to incomplete vaccination.•Midwife delivery was strongly associated with vaccination status. Vaccination status is often categorized as complete or not-complete. This ignores the potentially important heterogeneity in children whose vaccinations are not-complete. We sought to subcategorize not-completely vaccinated children and determine whether characteristics differed among these subgroups. This retrospective cohort study assessed vaccination status at 2 years of age for 43,965 children in the 2008 Alberta (Canada) birth cohort who were registered with provincial vital statistics records. Children were categorized (based on the five routinely scheduled childhood vaccines) as complete, incomplete, selective, or non-vaccination status. Characteristics derived from administrative health databases were used to determine factors associated with vaccination status. Population-level vaccination status at 2 years of age was found to be: 71.1% complete and 28.9% not complete (21.9% incomplete, 2.0% selective, and 5.1% non-vaccinated). Midwife delivery at home, compared to physician delivery in hospital, was strongly associated with non-vaccination status (adjusted odds ratio [aOR] 51.70, 95% CI 37.10–72.10). Factors that might pose barriers to vaccination, such as single marital status (aOR 1.58, 95% CI 1.49–1.67), large number of household children (≥4 vs. 1) (aOR 3.24, 95% CI 2.95–3.54), and multiple household moves (≥3 vs. 0) (aOR 1.69, 95% CI 1.35–2.10), were all strongly associated with incomplete vaccination status. Of the children who were not completely vaccinated at age 2, the vast majority had started but not completed the vaccination series, while a smaller number were selectively vaccinated or not vaccinated at all. Distinct differences are present among these groups that require attention when addressing vaccine coverage.

•Acellular vaccine provides moderate protection in the years following vaccination.•Young children who follow the vaccine schedule are well protected from pertussis.•The decrease in protection after 5 years is consistent with waning immunity. Pertussis is still frequently reported in Canada. In Alberta, pertussis incidence ranged from 1.8 to 20.5 cases per 100,000 persons for 2004–2015. Most cases occurred in those aged <15 years. In Alberta, acellular formulations replaced whole-cell in 1997. We investigated pertussis vaccine effectiveness (VE) using a test-negative design (TND) study. We included all persons who had a real-time PCR laboratory test for Bordetella pertussis between January 1, 2010 and August 31, 2015, in the province of Alberta, Canada. Vaccination history was obtained from Alberta’s immunization repository. Vaccination status was classified as complete, incomplete, or unvaccinated, based on the province’s vaccination schedule. Persons who had received ≥one dose of whole cell vaccine were excluded from analysis. Multivariable logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for pertussis infection by time since last vaccination. We adjusted for vaccination status, age, sex, neighbourhood income, urban/rural status, and the presence of a co-morbid condition. VE was calculated as [(1 − aOR) * 100]. Of the 12,149 tests available, 936 (7.7%) were positive for Bordetella pertussis. Among the full cohort, VE was 90% (95% CI 87–92%) at 1 year, 81% (95% CI 77–85%) at 1–3 years, 76% (95% CI 68–82%) at 4–7 years, and 37% (95% CI 11–56%) at 8 or more years since a last dose of acellular pertussis vaccine. Pertussis VE was highest in the first year after vaccination, then declined noticeably as years since a last vaccination increased. Our results suggest that a large number of adolescents and adults are susceptible to infection with Bordetella pertussis. Regular boosters throughout childhood, adolescence, and during pregnancy may be needed.

•Case reports suggest varicella vaccine may poses a risk for pediatric Arterial Ischemic Stroke.•No increased risk of Arterial Ischemic Stroke was found after varicella vaccination.•Parents and clinician should be reassured about the safety of the varicella vaccine. Background and purpose: Varicella disease is a risk factor for pediatric Arterial Ischemic Stroke (AIS). Isolated case reports have emerged suggesting that varicella vaccination may also pose a risk for AIS. Methods: This retrospective population-based cohort study assessed the risk of AIS in children who received a varicella-containing vaccine, as compared to those who did not. The study cohort consisted of children born between January 1, 2006 and December 31, 2013, in the Canadian province of Alberta, where all routine childhood vaccinations are publicly-funded, and recorded in a central immunization repository. These data were linked with hospital discharge abstract data to identify children diagnosed with AIS. A Cox proportional hazard model assessed the risk of AIS in the 12 months following vaccination for children receiving a varicella vaccine between 11 and 23 months of age, as compared to non-vaccinated children. Results: Of the 368,992 children in the cohort, 325,729 were vaccinated with a varicella-containing vaccine between 11 and 23 months of age. The rate of AIS was 7.8 (95% CI 4.8–10.9) per 100,000 person years at risk in the 12 months following varicella vaccination, as compared to 6.8 (95% CI 1.3–12.2) for children who did not receive a varicella vaccine. The adjusted Hazard Ratio for the risk of AIS, controlling for other AIS risk factors, in vaccinated children as compared to non-vaccinated children was 1.6 (95% CI 0.7–3.7) in the 12 months following vaccination and 1.7 (95% CI 0.5–4.9) in the 30 days following vaccination. Conclusions: Our study found no evidence of an increased risk of AIS following varicella vaccination. This population-based cohort study provides reassurance to parents and clinicians regarding the safety of varicella vaccination.

•Population-based study assessing shingles vaccine effectiveness.•Retrospective cohort of Albertans 50+ and older followed for six years.•Adjusted vaccine effectiveness (VE) is highest in the first year at 50.02%.•VE declines over time and vaccine provides little to no protection by the 5th year.•Provides important evidence for vaccine funding decisions. We assessed the effectiveness of shingles vaccine in preventing incident shingles among Alberta residents aged 50 years or older over the period 2009 – 2015, using administrative health data. The cohort comprised of Albertans from the Alberta Health Care Insurance Plan Registry (AHCIP) as of June 30, 2009 and aged 50 years or older. Those who received shingles vaccine were identified from the provincial pharmaceutical information network. The occurrence of incident shingles was identified through both inpatient and outpatients/community care data. Incident shingles was defined as the earliest dated record of ICD 9-CM 053 or ICD-10-CA B02. Starting on November 1, 2009, individuals with no history of shingles or shingles vaccination were followed until Nov 1, 2015 (6 years), or until shingles incidence, death, or AHCIP cancellation (including leaving Alberta). Vaccine effectiveness (VE) was estimated as the inverse of the relative risk of developing incident shingles in each year following vaccination compared to time at risk without vaccination, while adjusting for age, sex, income quintile, and immune compromising conditions (identified from physician claims, inpatient, and cancer registry data). There were 1,094,236 individuals in the cohort, with 85,439 (7.80%) vaccinated individuals. The shingles incidence rate was 9.03 [95% CI: 8.95, 9.11] cases per 1,000 person years (49,243 cases). Adjusted VE in the first year following immunization was 50.02% [95% CI: 44.71%, 54.83%] against incident shingles, decreasing to no effect by the fifth year (VE = 14.00% [95% CI: −20.99%, 38.88%]). Our findings are consistent with observations from other population based studies and provide population level data for policy-makers to review when making decisions related to public funding of shingles vaccine.