Determinants of non-vaccination against seasonal influenza during pregnancy.

OBJECTIVE: The objective of this study was to identify the determinants of influenza non-vaccination during pregnancy in Canada. METHODS: Biological mothers of children born between December 2018 and March 2019 were surveyed about vaccinations they had received during pregnancy, reasons for non-vaccination, obstetrical history, and demographics. Simple and multiple logistic regression models were used to measure associations between various sociodemographic factors as well as obstetrical history, and non-vaccination against influenza. We analyzed data from 2361 mothers. RESULTS: Factors associated with non-vaccination included being followed during pregnancy by a midwife compared to by an obstetrician-gynecologist (OR 2.02; 95% CI, 1.17‒3.50); having two or more past live births compared to none (OR 1.58; 95% CI, 1.01‒2.49); having an education level below high school diploma compared to a bachelor's degree or above (OR 2.50; 95% CI, 1.06‒5.90); and having a household income below $60,000 (OR 2.46; 95% CI, 1.42‒4.24) or between $60,000 and $99,999 (OR 2.77; 95% CI, 1.70‒4.52) compared to a household income of $140,000 or more. The province or territory of prenatal care proved to be an important factor in non-vaccination, with statistically significant odds ratios for certain provinces: OR 7.50 (95% CI, 1.40‒40.26) for Ontario, 8.23 (95% CI, 1.53‒44.23) for Newfoundland and Labrador, and 11.39 (95% CI, 2.14‒60.60) for Quebec, as compared to the territories. CONCLUSION: Despite universal access to influenza vaccines in Canada during pregnancy, regional variations and socioeconomic disparities in non-vaccination are still observable.

RéSUMé: OBJECTIF: Identifier les déterminants de la non-vaccination contre la grippe pendant la grossesse au Canada. MéTHODES: Notre étude porte sur 2 361 mères biologiques d'enfants nés entre décembre 2018 et mars 2019 qui ont été interrogées sur les vaccins reçus pendant leur grossesse, les raisons de non-vaccination, leurs antécédents obstétricaux, et leurs caractéristiques démographiques. Des modèles de régression logistique simple et multiple ont été utilisés pour mesurer les associations entre divers facteurs sociodémographiques, les antécédents obstétricaux, et la non-vaccination contre l'influenza. RéSULTATS: Les facteurs associés à la non-vaccination comprennent le suivi de grossesse par une sage-femme par rapport à un obstétricien-gynécologue (RC 2,02; IC 95% : 1,17‒3,50); avoir eu deux naissances vivantes ou plus par rapport à aucune (RC 1,58; IC 95% : 1,01‒2,49); avoir une scolarité inférieure au diplôme d'études secondaires par rapport à un baccalauréat ou plus (RC 2,50; IC 95% : 1,06‒5,90); et avoir un revenu du ménage inférieur à 60 000 $ (RC 2,46; IC 95% : 1,42‒4,24) ou entre 60 000 $ et 99 999 $ (RC 2,77; IC 95% : 1,70‒4,52) par rapport à un revenu ménager de 140 000 $ ou plus. La province ou le territoire de soins prénataux s'est avéré un facteur important de la non-vaccination avec des rapports de cote statistiquement significatifs pour certaines provinces : RC 7,50 (IC 95% : 1,40‒40,26) pour l'Ontario, 8,23 (IC 95% : 1,53‒44,23) pour Terre-Neuve-et-Labrador, et 11,39 (IC 95% : 2,14‒60,60) pour le Québec, comparativement aux territoires. CONCLUSION: Malgré l'accès universel aux vaccins antigrippaux au Canada durant la grossesse, des variations régionales et des disparités socioéconomiques en non-vaccination persistent.

Determinants of parental vaccine hesitancy in Canada: results from the 2017 Childhood National Immunization Coverage Survey.

BACKGROUND: In 2019, the World Health Organization (WHO) designated vaccine hesitancy as one of the ten leading threats to global health. Vaccine hesitancy exists when vaccination services are available and accessible, but vaccine uptake is lower than anticipated. It is often attributed to lack of trust in vaccine safety and effectiveness, or low level of concern about the risk of many vaccine-preventable diseases. This study aimed to examine the sociodemographic factors associated with parental vaccine hesitancy and vaccine refusal in Canada using data from the 2017 Childhood National Immunization Coverage Survey (CNICS). METHOD: The 2017 CNICS was a cross-sectional and nationally representative survey to estimate national vaccine uptake and to collect information about parents' Knowledge, Attitudes and Beliefs (KAB) regarding vaccination. Using the KAB questions, parental vaccine hesitancy (i.e., parental hesitation, delay or refusal of at least one recommended vaccination) and refusal (i.e., unvaccinated children) by sociodemographic factors was estimated using weighted prevalence proportions. A multinomial logistic regression model was fitted to examine associations between parental vaccine hesitancy or refusal and sociodemographic factors among parents of two-year-old children in Canada. Adjusted odds ratios (aOR) of being vaccine-hesitant or vaccine-refusing versus being non-vaccine-hesitant were generated. RESULTS: Both unadjusted and adjusted logistic regressions models showed that parents with lower household income (aOR 1.7, 95% CI 1.2-2.5), and those with a higher number of children in the household (aOR 2.2, 95% CI 1.4-3.5) had higher vaccine hesitancy. Conversely, lower vaccine hesitancy was observed among non-immigrant parents (aOR 0.4, 95% CI 0.3-0.6). In addition, lower household income (aOR 4.0, 95% CI 1.3-12.9), and higher number of children in the household (aOR 6.9, 95% CI 2.1-22.9) were significantly associated with parental vaccine refusal. Regional variations were also observed. CONCLUSION: Several sociodemographic determinants are associated with parental vaccine hesitancy and refusal. The findings of the study could help public health officials and policymakers to develop and implement targeted interventions to improve childhood vaccination programs.

Racial disparities in COVID-19 vaccination in Canada: results from the cross-sectional Canadian Community Health Survey.

BACKGROUND: Racial and ethnic disparities in COVID-19 vaccination coverage have been observed in Canada and in other countries. We aimed to compare vaccination coverage for at least 1 dose of a COVID-19 vaccine between First Nations people living off reserve and Métis, Black, Arab, Chinese, South Asian and White people. METHODS: We used data collected between June 2021 and June 2022 by Statistics Canada's Canadian Community Health Survey, a large, nationally representative cross-sectional study. The analysis included 64 722 participants aged 18 years or older from the 10 provinces. We used a multiple logistic regression model to determine associations between vaccination status and race, controlling for collection period, region of residence, age, gender and education. RESULTS: Nonvaccination against COVID-19 was more frequent in off-reserve First Nations people (adjusted odds ratio [OR] 1.8, 95% confidence interval [CI] 1.2-2.7) and Black people (adjusted OR 1.7, 95% CI 1.1-2.6), and less frequent among South Asian people (adjusted OR 0.3, 95% CI 0.1-0.7) compared to White people. INTERPRETATION: This analysis showed significant inequalities in COVID-19 vaccine uptake between racial/ethnic populations in Canada. Further research is needed to understand the sociocultural, structural and systemic facilitators of and barriers to vaccination across racial groups, and to identify strategies that may improve vaccination uptake among First Nations and Black people.

Pertussis Non-Vaccination During Pregnancy Despite Advice From Prenatal Care Providers.

OBJECTIVE: The purpose of this study was to measure the proportion of non-vaccination for pertussis in mothers in Canada who had been advised by their prenatal care provider to get vaccinated, and to identify sociodemographic factors and beliefs associated with non-vaccination. METHODS: The Survey on Vaccination during Pregnancy (part of childhood National Immunization Coverage Survey) included biological mothers of children born from September 2018 to March 2019. This analysis was restricted to 2657 mothers who had been advised by their prenatal care provider to get vaccinated against pertussis during pregnancy and knew whether or not they had been vaccinated. RESULTS: Of those who had been advised to get vaccinated against pertussis, 21% were not. This rate varied across provinces and territories, ranging from 9% in Prince Edward Island to 32% in Newfoundland and Labrador. Factors independently associated with pertussis non-vaccination included lower household income, having had past live births, and having received prenatal care from an obstetrician-gynecologist or a midwife compared to a family doctor. The risk of pertussis non-vaccination despite prenatal care advice was higher for those who disagreed that the baby would be at greater risk of pertussis if the mother did not get vaccinated. It was also higher for those who disagreed with statements regarding perceived benefits of vaccination. Conversely, disagreement with statements on perceived barriers was negatively associated with pertussis non-vaccination. CONCLUSION: These findings highlight the underlying factors associated with non-vaccination against pertussis despite prenatal care provider recommendation. Some inaccurate beliefs about pertussis and vaccination during pregnancy persist, leading to non-vaccination.

Sociodemographic Disparities in COVID-19 Vaccine Uptake and Vaccination Intent in Canada.

Introduction: This study's objective was to examine sociodemographic disparities in COVID-19 vaccine uptake and vaccination intent in the Canadian provinces by identifying factors associated with vaccine uptake in seniors prioritized for vaccination at the time of the survey and vaccination intent in all adults. Data and methods: A cross-sectional survey of Canadian adults was conducted in all provinces from mid-April to mid-May 2021. In addition to sociodemographic characteristics, respondents (n=10,678) provided information on their COVID-19 vaccination status or their intent to get vaccinated. Logistic regression models were fitted using sociodemographic factors as explanatory variables and vaccination status (unvaccinated vs at least one dose) or vaccination intent (unlikely versus likely or already vaccinated) as outcomes. To account for vaccine prioritization groups, multiple regression models were adjusted for province of residence, age, Indigenous identity and health care worker status. Results: Seniors with a lower household income (less than $60,000) and those living in smaller communities (fewer than 100,000 inhabitants) had higher odds of being unvaccinated. Among Canadian adults, the odds of being unlikely to get vaccinated were higher for males (adjusted odds ratio [AOR] 1.3), individuals younger than 60 (AOR between 3.3 and 5.1), non-health care workers (AOR 3.3), those with less than a high school education (AOR 3.4) or a household income of less than $30,000 (AOR 2.7) and individuals who do not identify as South Asian, Chinese, Black, Filipino, Arab, Latin American, Southeast Asian, West Asian, Korean or Japanese (AOR 1.7). Interpretation: COVID-19 vaccine uptake (80%) and vaccination intent (95%) were high among Canadians; however, relative disparities were observed among specific groups. Continued efforts targeted toward these groups are essential in reducing potential inequity in access or service provision.

Measuring inequalities in COVID-19 vaccination uptake and intent: results from the Canadian Community Health Survey 2021.

BACKGROUND: By July 2021, Canada had received enough COVID-19 vaccines to fully vaccinate every eligible Canadian. However, despite the availability of vaccines, some eligible individuals remain unvaccinated. Differences in vaccination uptake can be driven by health inequalities which have been exacerbated and amplified by the pandemic. This study aims to assess inequalities in COVID-19 vaccination uptake and intent in adults 18 years or older across Canada by identifying sociodemographic factors associated with non-vaccination and low vaccination intent using data drawn from the June to August 2021 Canadian Community Health Survey (CCHS). METHODS: The CCHS is an annual cross-sectional and nationally representative survey conducted by Statistics Canada, which collects health-related information. Since September 2020, questions about the COVID-19 pandemic are asked. Adjusted logistic regression models were fitted to examine associations between vaccination uptake or intent and sociodemographic and health related variables. Region, age, gender, level of education, Indigenous status, visible minority status, perceived health status, and having a regular healthcare provider were considered as predictors, among other factors. RESULTS: The analysis included 9,509 respondents. The proportion of unvaccinated was 11%. Non-vaccination was associated with less than university education (aOR up to 3.5, 95% CI 2.1-6.1), living with children under 12 years old (aOR 1.6, 95% CI 1.1-2.4), not having a regular healthcare provider (aOR 1.6, 95% CI 1.1-2.2), and poor self-perceived health (aOR 1.8, 95% CI 1.3-2.4). Only 5% of the population had low intention to get vaccinated. Being unlikely to get vaccinated was associated with the Prairies region (aOR 2.2, 95% CI 1.2-4.1), younger age groups (aOR up to 4.0, 95% CI 1.3-12.3), less than university education (aOR up to 3.8, 95% CI 1.9-7.6), not being part of a visible minority group (aOR 3.0, 95% CI 1.4-6.4), living with children under 12 years old (aOR 1.8, 95% CI 1.1-2.9), unattached individuals (aOR 2.6, 95% CI 1.1-6.1), and poor self-perceived health (aOR 2.0, 95% CI 1.3-2.9). CONCLUSIONS: Disparities were observed in vaccination uptake and intent among various sociodemographic groups. Awareness of inequalities in COVID-19 vaccination uptake and intent is needed to determine the vaccination barriers to address in vaccination promotion strategies.

Pertussis Vaccination in Canadian Pregnant Women, 2018-2019.

OBJECTIVE: This study was undertaken to measure the uptake of pertussis vaccination during pregnancy in Canada and to identify sociodemographic factors associated with non-vaccination. METHODS: A total of 5091 biological mothers of children born between September 2, 2018, and March 1, 2019, were interviewed about pertussis vaccination during their pregnancy. RESULTS: Among 4607 mothers who recalled whether they had been vaccinated for pertussis, 43% had been vaccinated and 57% had not. The main reason given by mothers for not having been vaccinated was not being aware that pertussis vaccination was recommended. Factors independently associated with non-vaccination were being born outside Canada, lower household income, living in a province or territory where pertussis vaccination was not provided free of charge, having had previous live births, and having received maternity care from a midwife. CONCLUSION: Advice from the maternity care provider is an important driver of pertussis vaccination during pregnancy.

Determinants of non-vaccination against seasonal influenza.

BACKGROUND: In Canada, vaccine coverage for seasonal influenza remains below targets. Few studies have sought to determine the sociodemographic factors associated with non-vaccination using a Canada-wide survey. This study aims to identify the determinants of, and the reasons for, non-vaccination. DATA AND METHODS: Data from the 2013/2014 Canadian Community Health Survey (CCHS) were used. Respondents were divided into three groups: adults aged 18 to 64 years with a chronic medical condition (CMC), adults in the same age group with no CMC, and adults aged 65 years and older. Logistic regressions were used to measure the association between sociodemographic factors and non-vaccination. RESULTS: Among adults aged 65 years and older, the proportion of non-vaccinated persons was 36.2%. This proportion was higher among adults aged 18 to 64 years with a CMC and those with no CMC (62.2% and 77.8%, respectively). Factors independently associated with non-vaccination in all groups included being young, having a lower level of education, and not having a family doctor. Among adults aged 65 years and older and 18 to 64 years with a CMC, excellent self-perceived health was also associated with non-vaccination. The belief that the vaccine is not necessary was the most common reason for non-vaccination. DISCUSSION: Too few Canadians get the influenza vaccine. The main reasons for not getting vaccinated have more to do with personal decision than barriers to access. This illustrates the ongoing need to inform the public about the importance of the vaccine and the risks associated with influenza.

Low levels of detectable pertussis antibody among a large cohort of pregnant women in Canada.

Newborns and infants less than 6 months of age continue to be at highest risk of severe outcomes from pertussis infection. Pertussis vaccination during the last trimester of pregnancy can confer protection to newborns as a result of trans-placental transfer of pertussis antibodies. In several countries, pertussis vaccination in pregnancy is recommended routinely and Canada's National Advisory Committee on Immunization issued similar routine recommendations in February 2018. Using second trimester biobanked plasma samples (n = 1752) collected between 2008 and 2011, we measured the pre-existing anti-pertussis toxin (PT) levels in a large cohort of second-trimester pregnant women using a commercial ELISA test. We found that 97.5% of these women had anti-PT IgG titres below 35 IU/mL. Women with higher incomes had slightly higher anti-PT levels but 96% still had titres <35 IU/ml. In conclusion, almost all of the pregnant women in this large cohort had anti-PT levels low enough to suggest susceptibility to pertussis infection in both the mothers and their newborn infants.

Determinants of non-vaccination against seasonal influenza in Canadian adults: findings from the 2015-2016 Influenza Immunization Coverage Survey.

OBJECTIVES: The study objectives were to (1) identify determinants of non-vaccination against seasonal influenza in Canadian adults and (2) examine self-reported reasons for non-vaccination. METHODS: The data source was the 2015-2016 Influenza Immunization Coverage Survey, a national telephone survey of Canadian adults. Participants (n = 1950) were divided into three groups: adults aged 18-64 years with (n = 408) and without (n = 1028) chronic medical conditions (CMC) and adults ≥ 65 years (n = 514). Logistic regression was used to measure associations between sociodemographic factors and non-vaccination for the 2015-2016 influenza season. Weighted proportions were calculated to determine the main self-reported reasons for not receiving the influenza vaccine. RESULTS: Younger age was found to be associated with non-vaccination across all groups. In adults ≥ 65 years, elementary- or secondary- vs. university-level education (aOR 1.87, 95% CI 1.14-3.06) was also significantly associated with non-vaccination. Significant variation in vaccine uptake was found for several sociodemographic factors in adults aged 18-64 without CMC. Low perceived susceptibility or severity of influenza and lack of belief in the vaccine's effectiveness were the most commonly reported reasons for not receiving the vaccine. CONCLUSION: In general, our results were consistent with findings from other Canadian and American studies on seasonal influenza vaccine uptake. Belief that the influenza vaccine is not needed was common, even among those at increased risk of influenza-related complications. Additional research is needed to better understand how sociodemographic factors such as income and education may influence uptake and to raise awareness of potential complications from influenza infection in high-risk adults.

Delayed measles vaccination of toddlers in Canada: Associated socio-demographic factors and parental knowledge, attitudes and beliefs.

Delaying vaccination increases the period of vulnerability of children against vaccine-preventable diseases. We used a nationally representative sample of Canadian two-year-old children to explore factors associated with delays in the uptake of the first dose of measles-containing vaccine, recommended in Canada for children at 12 months of age. Distribution of delays was determined using data from the 2013 Childhood National Immunization Coverage Survey. Logistic regression was used to examine sociodemographic factors and knowledge, attitudes and beliefs (KAB) associated with the two outcomes of interest: delays of one to six months (vaccination at 13 to 18 months of age) and delays of seven to 18 months (vaccination at 19 to 23 months of age). Overall, 69% (95% confidence interval [CI] 67-71) of children received their first valid dose on time. Twenty-nine percent (95% CI 27-31) and 11% (95% CI 9-12) of children were unvaccinated before turning 13 and 16 months of age, respectively. Factors associated with delays of one to six months were being a girl, being born outside Canada, and the jurisdiction of residence. Being from a single-parent family, being born outside Canada and the jurisdiction of residence were associated with delays of seven to 18 months, suggesting that potential barriers might be at play. Associations between KAB and vaccination delays indicate that vaccine hesitancy could contribute to measles vaccination delays in Canada. Barriers in accessing vaccination services and the role of vaccine hesitancy in timely vaccination must be better understood to reduce vaccination delays in toddlers in Canada.

Methods used for immunization coverage assessment in Canada, a Canadian Immunization Research Network (CIRN) study.

Accurate and complete immunization data are necessary to assess vaccine coverage, safety and effectiveness. Across Canada, different methods and data sources are used to assess vaccine coverage, but these have not been systematically described. Our primary objective was to examine and describe the methods used to determine immunization coverage in Canada. The secondary objective was to compare routine infant and childhood coverage estimates derived from the Canadian 2013 Childhood National Immunization Coverage Survey (cNICS) with estimates collected from provinces and territories (P/Ts). We collected information from key informants regarding their provincial, territorial or federal methods for assessing immunization coverage. We also collected P/T coverage estimates for select antigens and birth cohorts to determine absolute differences between these and estimates from cNICS. Twenty-six individuals across 16 public health organizations participated between April and August 2015. Coverage surveys are conducted regularly for toddlers in Quebec and in one health authority in British Columbia. Across P/Ts, different methodologies for measuring coverage are used (e.g., valid doses, grace periods). Most P/Ts, except Ontario, measure up-to-date (UTD) coverage and 4 P/Ts also assess on-time coverage. The degree of concordance between P/T and cNICS coverage estimates varied by jurisdiction, antigen and age group. In addition to differences in the data sources and processes used for coverage assessment, there are also differences between Canadian P/Ts in the methods used for calculating immunization coverage. Comparisons between P/T and cNICS estimates leave remaining questions about the proportion of children fully vaccinated in Canada.

Seroprevalence of rubella antibodies and determinants of susceptibility to rubella in a cohort of pregnant women in Canada, 2008-2011.

Long term control of rubella and congenital rubella syndrome relies on high population-level immunity against rubella, particularly among women of childbearing age. In Canada, all pregnant women should be screened so that susceptible new mothers can be offered vaccination for rubella before discharge. This study was undertaken to estimate rubella susceptibility in a cohort of pregnant women in Canada and to identify associated socio-economic and demographic factors. Biobanked plasma samples were obtained from the Maternal-Infant Research on Environmental Chemicals (MIREC) study, in which pregnant women were recruited between 2008 and 2011. Socio-demographic characteristics and obstetric histories were collected. Second trimester plasma samples (n=1,752) were tested for rubella-specific IgG using an in-house enzyme-linked immunosorbent assay. The percentage of women with IgG titers <5IU/mL, 5-10IU/mL, and ≥10IU/mL were 2.3%, 10.1%, and 87.6%, respectively. Rates of seronegativity, defined as <5IU/mL, were 3.1% in women who had no previous live birth and 1.6% in women who had given birth previously. Among the latter group, seronegativity was higher in women with high school education or less (adjusted OR (aOR) 5.93, 95% CI 2.08-16.96) or with a college or trade school diploma (aOR 3.82, 95% CI 1.45-10.12), compared to university graduates, and those born outside Canada (aOR 2.60, 95% CI 1.07-6.31). In conclusion, a large majority of pregnant women were found to be immune to rubella. Further research is needed to understand inequalities in vaccine uptake or access, and more effort is needed to promote catch-up measles-mumps-rubella vaccination among socioeconomically disadvantaged and immigrant women of childbearing age.

Determinants of non-vaccination and incomplete vaccination in Canadian toddlers.

Vaccination coverage remains suboptimal in Canada and sporadic outbreaks of vaccine-preventable diseases such as measles and pertussis continue to occur. This study was undertaken to identify sociodemographic determinants of total non-vaccination (having never received any vaccine), non-vaccination for measles (0 doses) and incomplete vaccination for pertussis (< 4 doses) among 2-year-old Canadian children. Data from the 2013 Childhood National Immunization Coverage Survey (CNICS) were used. Associations between sociodemographic factors and outcomes were measured by multiple logistic regressions and adjusted odds ratios (aOR) were calculated. A total of 5,477 children were included in the analyses of total non-vaccination, and 3,899 children were included in the analysis of non-vaccination for measles and incomplete vaccination for pertussis. Overall, 2.7% of children (95% CI 2.0-3.3) had received no vaccine at all. Lower parental education, i.e., the responding parent having a high school diploma, trade certificate or less (compared with university graduation) was associated with total non-vaccination (aOR 1.99, 95% CI 1.02-3.91). Non-vaccination for measles was more frequent among children of single parent families (aOR 1.63, 95% CI 1.01-2.61) and those of parents with lower education (aOR 1.86, 95% CI 1.26-2.76). The odds of incomplete vaccination for pertussis was greater among children born outside Canada (aOR 3.10, 95% CI 1.73-5.58), of parents with lower education (aOR 1.92, 95% CI 1.41-2.62), and those whose household income was between $40,000 and $59,999 (aOR 1.47; 95% CI 1.04-2.07) or lower than $40,000 (aOR 1.58, 95% CI 1.13-2.22). Significant regional variation was also found for all outcomes. In conclusion, despite universal access to free childhood vaccines in Canada, regional variation and socioeconomic inequalities in vaccine uptake were still observed. Further analyses are warranted to identify barriers contributing to these variations.

Infant mortality at term in Canada: Impact of week of gestation.

OBJECTIVES: Infants born at term have low mortality, but risk may vary from week to week. We determined the risk of infant mortality at term by gestational week and cause. METHODS: We analyzed 4.1 million infants born at ≥37weeks of gestation in Canada from 1991 to 2010, followed for mortality the first year of life. We estimated hazard ratios (HR) and 95% CIs for early, late and post neonatal mortality from 37 through 41weeks of gestation, adjusting for individual characteristics. The main outcomes were mortality due to congenital anomaly, asphyxia, immaturity, infection, sudden infant death, and injury. RESULTS: Infant mortality decreased progressively from 4.55 per 1000 at 37weeks to 1.62 per 1000 at 41weeks. Early neonatal mortality varied little between 39 and 41weeks, but post neonatal mortality was lowest at 40-41weeks. Relative to 41weeks of gestation, mortality at 39weeks was higher for congenital anomaly (HR 1.30, 95% CI 1.05-1.60) and sudden infant death (HR 1.58, 95% CI 1.18-2.11). CONCLUSION: In Canada, mortality at term is lowest for infants born at 40 or 41weeks of gestation, especially at late and post neonatal ages, and for congenital anomaly and sudden infant death.

Estimates and determinants of HPV non-vaccination and vaccine refusal in girls 12 to 14 y of age in Canada: Results from the Childhood National Immunization Coverage Survey, 2013.

Since the introduction of HPV vaccination programs in Canada in 2007, coverage has been below public health goals in many provinces and territories. This analysis investigated the determinants of HPV non-vaccination and vaccine refusal. Data from the Childhood National Immunization Coverage Survey (CNICS) 2013 were used to estimate the prevalence of HPV non-vaccination and parental vaccine refusal in girls aged 12-14 years, for Canada and the provinces and territories. Multivariate logistic regression was used to examine factors associated with non-vaccination and vaccine refusal, after adjusting for potential confounders. An estimated 27.7% of 12-14 y old girls had not been vaccinated against HPV, and 14.4% of parents reported refusing the vaccine. The magnitude of non-vaccination and vaccine refusal varied by province or territory and also by responding parent's country of birth. In addition, higher education was associated with a higher risk of refusal of the HPV vaccine. Rates of HPV non-vaccination and of refusal of the HPV vaccine differ and are influenced by different variables. These findings warrant further investigation.

Associations of Pregnancy Outcomes and PM2.5 in a National Canadian Study.

BACKGROUND: Numerous studies have examined associations between air pollution and pregnancy outcomes, but most have been restricted to urban populations living near monitors. OBJECTIVES: We examined the association between pregnancy outcomes and fine particulate matter in a large national study including urban and rural areas. METHODS: Analyses were based on approximately 3 million singleton live births in Canada between 1999 and 2008. Exposures to PM2.5 (particles of median aerodynamic diameter ≤ 2.5 µm) were assigned by mapping the mother's postal code to a monthly surface based on a national land use regression model that incorporated observations from fixed-site monitoring stations and satellite-derived estimates of PM2.5. Generalized estimating equations were used to examine the association between PM2.5 and preterm birth (gestational age < 37 weeks), term low birth weight (< 2,500 g), small for gestational age (SGA; < 10th percentile of birth weight for gestational age), and term birth weight, adjusting for individual covariates and neighborhood socioeconomic status (SES). RESULTS: In fully adjusted models, a 10-µg/m(3) increase in PM2.5 over the entire pregnancy was associated with SGA (odds ratio = 1.04; 95% CI 1.01, 1.07) and reduced term birth weight (-20.5 g; 95% CI -24.7, -16.4). Associations varied across subgroups based on maternal place of birth and period (1999-2003 vs. 2004-2008). CONCLUSIONS: This study, based on approximately 3 million births across Canada and employing PM2.5 estimates from a national spatiotemporal model, provides further evidence linking PM2.5 and pregnancy outcomes.

Differences in perinatal and infant mortality in high-income countries: artifacts of birth registration or evidence of true differences?

BACKGROUND: Variation in birth registration criteria may compromise international comparisons of fetal and infant mortality. We examined the effect of birth registration practices on fetal and infant mortality rates to determine whether observed differences in perinatal and infant mortality rates were artifacts of birth registration or reflected true differences in health status. METHODS: A retrospective population-based cohort study was done using data from Canada, United States, Denmark, Finland, Iceland, Norway, and Sweden from 1995-2005. Main outcome measures included live births by gestational age and birth weight; gestational age-and birth weight-specific stillbirth rates; neonatal, post-neonatal, and cause-specific infant mortality. RESULTS: Proportion of live births <22 weeks varied substantially: Sweden (not reported), Iceland (0.00%), Finland (0.001%), Denmark (0.01%), Norway (0.02%), Canada (0.07%) and United States (0.08%). At 22-23 weeks, neonatal mortality rates were highest in Canada (892.2 per 1000 live births), Denmark (879.3) and Iceland (1000.0), moderately high in the United States (724.1), Finland (794.3) and Norway (739.0) and low in Sweden (561.2). Stillbirth:live birth ratios at 22-23 weeks were significantly lower in the United States (79.2 stillbirths per 100 live births) and Finland (90.8) than in Canada (112.1), Iceland (176.2) and Norway (173.9). Crude neonatal mortality rates were 83% higher in Canada and 96% higher in the United States than Finland. Neonatal mortality rates among live births ≥ 28 weeks were lower in Canada and United States compared with Finland. Post-neonatal mortality rates were higher in Canada and United States than in Nordic countries. CONCLUSIONS: Live birth frequencies and stillbirth and neonatal mortality patterns at the borderline of viability are likely due to differences in birth registration practices, although true differences in maternal, fetal and infant health cannot be ruled out. This study emphasises the need for further standardisations, in order to enhance the relevance of international comparisons of infant mortality.