Exploring the heterogeneity among partially vaccinated children in a population-based cohort

Impact of maternal depression and anxiety on immunization status of children: a prospective cohort study

BACKGROUND

Maternal depression and anxiety can have a detrimental impact on birth outcomes and healthy child development; there is limited knowledge on its influence on immunization schedule adherence. Therefore, the objectives of this study were to determine the impact of maternal depression and anxiety in the perinatal period on prolonged vaccine delay of childhood vaccines.

METHODS

In this prospective cohort study, we analyzed linked survey and administrative data of 2,762 pregnant women in Calgary, Alberta, Canada. Data were collected at two time-points: prenatal (< 25 weeks of gestation) and postpartum (4 months postpartum). We used multivariable logistic regression to examine the association between depression and anxiety with prolonged immunization delay, adjusting for covariates.

RESULTS

In multivariable analysis, maternal depression at either time point was not associated with prolonged delay for DTaP-IPV-Hib (OR 1.16, 95% CI 0.74-1.82), MMR/MMRV (OR 1.03, 95% CI 0.72-1.48), or all routine childhood vaccines combined (OR 1.32, 95% CI 0.86-2.04). Maternal anxiety at either time point was also not associated with prolonged delayed for DTaP-IPV-Hib (OR 1.08, 95% CI 0.77-1.53), MMR/MMRV (OR 1.07, 95% CI 0.82-1.40), or all vaccines combined (OR 1.00, 95% CI 0.80-1.26). In both the depression and anxiety models, children of Canadian-born mothers had higher odds of prolonged delay, as did those with low-income mothers.

CONCLUSION

Health care providers can be reassured that maternal depression and anxiety do not appear to influence maternal commitment to routine immunization. Findings suggested that low income and household moves may influence adherence to vaccine schedules and health care providers may want to provide anticipatory guidance to these families.

Improved vaccine coverage for First Nations children receiving first dose on-reserve: a retrospective cohort study in western Canada

INTRODUCTION

Fragmentation in immunisation reporting systems pose challenges in measuring vaccine coverage for First Nations children in Canada. Some Nations have entered into data-sharing agreements with the province of Alberta's health ministry, enabling novel opportunities to calculate coverage.

METHODS

Partnering with a First Nations community in Alberta, this retrospective cohort study calculated routine childhood vaccine coverage. Administrative data for vaccines delivered within and outside the community were linked to calculate partial and complete immunisation coverage in 2013-2019 at ages 2 and 7 years for children living in the community. We also compared vaccine coverage each year for (a) children who were and were not continuous community residents and (b) children who received or not their first vaccine at the on-reserve community health centre. We also calculated the mean complete coverage across all study years with 95% CIs.

RESULTS

For most vaccines, coverage was higher (p<0.05) at ages 2 and 7 years for children that received their first vaccine at the First Nations health centre, compared with those who received their first dose elsewhere. For example, for pneumococcal vaccine, the mean level of complete coverage in 2-year-olds was 55.7% (52.5%-58.8%) for those who received their first vaccine in the community, compared with 33.3% (29.4%-37.3%) for those who did not; it was also higher at 7 years (75.6%, 72.7%-78.5%, compared with 55.5%, 49.7%-61.3%).

CONCLUSION

Initiating the vaccine series at the on-reserve community health centre had a positive impact on coverage. The ability to measure accurate coverage through data-sharing agreements and vaccine record linkage will support First Nations communities in identifying individual and community immunity. The findings also support the transfer of health funding and service delivery to First Nations to improve childhood immunisation uptake.

Predictors and impact of trust on vaccine decisions in parents of 2-year-old children in Canada: findings from the 2017 Childhood National Immunization Coverage Survey (cNICS)

Trust is known to be an important factor in vaccine decisions for parents of young children, but there has been a lack of Canadian data measuring the determinants and impact of trust. Using data from the 2017 Canadian Childhood National Immunization Coverage Survey (cNICS), this study analyzed the relationships between sources that parents trust for vaccine information and demographics, parental knowledge, attitudes, and beliefs (KAB) and vaccine decisions (refusal, delay or reluctance) in parents of 2-year-old children who had accepted at least one vaccine for their child (n = 6125). The findings show that 83% of parents trust doctors for vaccine information; 70-80% trust pharmacists, PMH, nurses and HC/PHAC; 34% trust family and 23% trust friends and CAM HCPs. However, parents found to have poor or moderate KAB were less likely to trust doctors, nurses, pharmacists, PMH and HC/PHAC. Parents were also less likely to trust the PMH or HC/PHAC if they had high school education or less or trade/college education, or were widowed, separated, or divorced. Parents who had never been reluctant to vaccinate their 2-year-old child were over 2 times more likely to trust doctors, nurses, pharmacists, PMH and HC/PHAC while parents who trusted family and friends were less likely to delay or refuse vaccines. There was also significant regional variation within Canada, with parents from Quebec most likely to trust doctors, nurses, pharmacists, friends, PMH and HC/PHAC. Parents from the Territories were less likely to trust doctors, nurses and pharmacists, but more likely to trust family. Parents were less likely to trust doctors if they were from the Prairies, and pharmacists if they were from BC, and parents from the Prairies and BC were less likely to trust HC/PHAC. Parents from Ontario were less likely to trust family or friends, but more likely to trust the PMH. Tailored vaccine campaigns are needed to account for educational, marital, and regional differences across Canada to improve vaccine uptake.

Determinants of vaccine refusal, delay and reluctance in parents of 2-year-old children in Canada: Findings from the 2017 Childhood National Immunization Coverage Survey (cNICS)

Vaccine hesitancy is a barrier to improving childhood vaccination rates in Canada, but the scope of this problem is unclear due to inconsistent measurement of vaccine uptake indicators. Using 2017 data from a Canadian national vaccine coverage survey, this study analyzed the impact of demographics and parental knowledge, attitudes and beliefs (KAB) on vaccine decisions (refusal, delay and reluctance) in parents of 2-year-old children who had received at least one vaccine. The findings show that 16.8% had refused a vaccine, specifically influenza (73%), rotavirus (13%) and varicella (9%); female parents or those from Quebec or the Territories more likely to refuse. 12.8% were reluctant to accept a vaccine, usually influenza (34%), MMR (21%) and varicella (19%), but eventually accepted them upon advice from a health care provider. 13.1% had delayed a vaccine, usually because their child had health issues (54%) or was too young (18.6%) and was predicted by five or six person households. Recent immigration to Canada decreased likelihood of refusal, delay, or reluctance; however, after 10 years in Canada, these parents were as likely to refuse or be reluctant as parents born in Canada. Poor KAB increased likelihood of refusal and delay by 5 times, and reluctance by 15 times, while moderate KAB increased likelihood of refusal (OR 1.6), delay (OR 2.3) and reluctance (OR 3.6). Future research into vaccine decisions by female and/or single parents, and predictors of vaccine KAB would provide valuable information and help protect our children from vaccine preventable diseases.

Design of a Reminder and Recall System in a Contact Tracing Application to Support Coronavirus Booster Vaccination

OBJECTIVES

The rate of coronavirus disease 2019 (COVID-19) booster vaccination in Indonesia remains relatively low, representing 15.33% of the overall vaccination target as of April 2022. The implementation of a reminder and recall system has been shown to be effective in increasing vaccination rates. In prior research, reminders and recalls were sent through traditional media, such as mail, and had not yet been integrated into modern media, such as smartphone applications and (in particular) contact tracing applications. Therefore, the present study was conducted to design a reminder and recall system for the PeduliLindungi contact tracing application.

METHODS

We used the design science research (DSR) methodology with three iterations. The first iteration produced a low-fidelity prototype (or wireframe), and the next yielded a high-fidelity (clickable) prototype.

RESULTS

The final prototype included three main features: a reminder and recall mechanism, online registration for COVID-19 booster vaccination, and educational articles. The evaluation consisted of interviews in the first iteration, interviews and the System Usability Scale (SUS) questionnaire in the second, and the Post-Study System Usability Questionnaire (PSSUQ) in the third. The SUS value obtained in the second iteration was 71.6, indicating good (acceptable) results, while in the third iteration, the system usefulness, information quality, interface quality, and overall PSSUQ values were 2.456, 2.473, 2.230, and 2.397, respectively, indicating good quality of the resulting design.

CONCLUSIONS

This research contributes to two areas: implementation of a reminder and recall system in the PeduliLindungi contact tracing application and enhancement of contact tracing applications using DSR methodology.

Factors Associated with Vaccination Uptake among Young Children: A Follow-Up Study of 1799 Toddlers

Childhood vaccination is crucial to protect young children from harmful infectious diseases. This study aimed to investigate the recent childhood immunization rate of recommended and additional vaccinations and identify the factors affecting the vaccination uptake of young children in Hong Kong. The self-administrated questionnaires were distributed to parents of toddlers aged 2 to 5. They were asked to provide information on (1) socioeconomic demographic factors; (2) experiences during pregnancy; and (3) the medical history of the toddler. A total of 1799 responses were collected. Children were more likely to be fully vaccinated when they were at a younger age (aOR = 0.61, 95% CI: 0.48–0.78, p < 0.001), the first child in the family (aOR second-born = 0.62, 95% CI: 0.48–0.81, p < 0.001; aOR third-born = 0.33, 95% CI: 0.19–0.55, p < 0.001), had a higher household income (aOR HKD 15,000–HKD 29,999 = 1.80, 95% CI: 1.27–2.55, p = 0.001; aOR ≥ HKD 30,000 = 3.42, 95% CI: 2.39–4.90, p < 0.001; compared with <HKD 15,000), or with mothers in older age groups (aOR 35–39 years old = 2.45, 95% CI = 1.22–4.93, p = 0.012; aOR ≥ 40 = 2.90, 95% CI = 1.24–6.77, p = 0.014; compared with ≤ age 24). The uptake of any additional vaccination was 71%. Children who were older (aOR = 1.32, 95% CI: 1.02–1.70, p = 0.036), the first child in the family (aOR second-born = 0.74, 95% CI: 0.56–0.99, p = 0.043; aOR third-born = 0.55, 95% CI: 0.32–0.96, p = 0.034), with higher household income (aOR ≥ HKD 30,000 = 1.61, 95% CI: 1.10–2.37, p = 0.016), were exposed to second-hand smoke from the father (aOR: 1.49, 95% CI: 1.08–2.07, p = 0.016), experienced hospitalization (twice or more—aOR: 1.44, 95% CI: 1.04–1.99, p = 0.027), or were fully vaccinated (aOR: 2.76, 95% CI: 2.12–3.60, p < 0.001) were associated with a higher chance of taking an additional vaccine. To encourage the vaccination rate, more attention should be given to families with more children, low-income families, and younger mothers.

Text Message Reminders to Improve Immunization Appointment Attendance in Alberta, Canada: The Childhood Immunization Reminder Project Pilot Study

BACKGROUND

Vaccine coverage for 18-month-old children in Canada is often below the recommended level, which may be partially because of parental forgetfulness. SMS text message reminders have been shown to potentially improve childhood immunization uptake but have not been widely used in Alberta, Canada. In addition, it has been noted that language barriers may impede immunization service delivery but continue to remain unaddressed in many existing reminder and recall systems.

OBJECTIVE

This study aimed to assess the effectiveness and acceptability of using SMS text messages containing a link to web-based immunization information in different languages to remind parents of their child's 18-month immunization appointment.

METHODS

The Childhood Immunization Reminder Project was a pilot intervention at 2 public health centers, one each in Lethbridge and Edmonton, Alberta, Canada. Two SMS text message reminders were sent to parents: a booking reminder 3 months before their child turned 18 months old and an appointment reminder 3 days before their scheduled appointment. Booking reminders included a link to the study website hosting immunization information in 9 languages. To evaluate intervention effectiveness, we compared the absolute attendance no-show rates before the intervention and after the intervention. The acceptability of the intervention was evaluated through web-based surveys completed by parents and public health center staff. Google Analytics was used to determine how often web-based immunization information was accessed, from where, and in which languages.

RESULTS

Following the intervention, the health center in Edmonton had a reduction of 6.4% (95% CI 3%-9.8%) in appointment no-shows, with no change at the Lethbridge Health Center (0.8%, 95% CI -1.4% to 3%). The acceptability surveys were completed by 222 parents (response rate: 23.9%) and 22 staff members. Almost all (>95%) respondents indicated that the reminders were helpful and provided useful suggestions for improvement. All surveyed parents (222/222, 100%) found it helpful to read web-based immunization information in their language of choice. Google Analytics data showed that immunization information was most often read in English (118/207, 57%), Punjabi (52/207, 25.1%), Arabic (13/207, 6.3%), Spanish (12/207, 5.8%), Italian (4/207, 1.9%), Chinese (4/207, 1.9%), French (2/207, 0.9%), Tagalog (1/207, 0.5%), and Vietnamese (1/207, 0.5%).

CONCLUSIONS

The study's findings support the use of SMS text message reminders as a convenient and acceptable method to minimize parental forgetfulness and potentially reduce appointment no-shows. The diverse languages accessed in web-based immunization information suggest the need to provide appropriate translated immunization information. Further research is needed to evaluate the impact of SMS text message reminders on childhood immunization coverage in different settings.

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.

Immunization status of children at kindergarten entry in Alberta, Canada

OBJECTIVES

Little is known about immunization coverage among kindergarten-aged children in jurisdictions that do not require children's immunization records to be provided at school entry. Thus, we assessed immunization coverage and associated characteristics of a 2008 birth cohort of Alberta children at kindergarten entry as compared with at the end of grade one.

METHODS

This retrospective cohort study used population-based administrative health data for childhood vaccines in Alberta, Canada. We categorized and compared immunization status of children as follows: (a) complete at kindergarten entry; (b) incomplete at kindergarten entry but complete at the end of grade one; and (c) still incomplete at the end of grade one. To assess factors associated with immunization status, we used multinomial logistic regression.

RESULTS

Immunization coverage for the complete vaccine series for children (N = 41,515) at kindergarten entry was suboptimal (44.5%, 95% CI 44.0-45.0) and substantially lower than for children at the end of grade one (74.8%, 95% CI 74.3-75.2). Young maternal age, not living with a partner, and having > 1 child in a household were associated with incomplete immunization status at kindergarten entry. Midwife-assisted hospital and home delivery was strongly associated with incomplete immunization status at the end of grade one.

CONCLUSION

Immunization coverage at kindergarten entry was strikingly low. Risk factors for incomplete immunization status were identified that require particular attention when addressing immunization coverage. The school-based catch-up immunization program in grade one seems to have substantially improved coverage among children, suggesting a potential benefit of shifting the catch-up program from grade one to kindergarten entry.

Childhood immunization appointment reminders and recalls: strengths, weaknesses and opportunities to increase vaccine coverage

OBJECTIVES

Childhood immunization coverage has been shown to be greatly impacted by parental forgetfulness regarding immunizations and appointments. Evidence supports the use of reminders and recalls to overcome this barrier, which remind parents about upcoming immunization appointments and inform them once their child is overdue for an immunization. In this study, we sought to identify reminder/recall strategies used throughout a large Canadian province and determine the perceived strengths, weaknesses and areas of improvement of existing strategies.

STUDY DESIGN AND METHODS

An environmental scan was performed in 2018 in two phases: (1) interviews with public health leaders from the five zones of Alberta and (2) an online survey of public health centres across the province. Data analysis occurred in 2018 and 2019.

RESULTS

Commonly reported strengths of reminders and recalls included their ability to increase appointment attendance and remind parents about immunizations, respectively. A major identified weakness was their time-consuming/resource-intensive nature. Many participants believed reminder/recalls could be improved by modernizing delivery methods. Educational information or strategies to overcome language barriers were rarely incorporated into reminder/recall systems.

CONCLUSIONS

There was support for incorporating text messaging and automation into reminder/recall systems while encouraging continued exploration of novel reminder/recall delivery methods. Tailoring reminder/recalls to the needs and preferences of target populations can maximize the effectiveness of these systems. This includes modernizing methods of delivery, addressing language barriers, providing educational information, and allotting some degree of flexibility to local level management of reminder/recalls.

Effective interventions to increase routine childhood immunization coverage in low socioeconomic status communities in developed countries: A systematic review and critical appraisal of peer-reviewed literature

OBJECTIVES

Childhood immunization coverage rates are known to be disproportionate according to population's socioeconomic status (SES). This systematic review examined and appraised quality of interventions deemed effective to increase routine childhood immunization uptake in low SES populations in developed countries.

METHODS

A literature search was conducted using Medline, Embase, CINAHL, EBMR, PsycInfo, PubMed, and Health STAR. We systematically searched and critically appraised articles published between January 1990 and December 2019 using the Effective Public Health Practice Project Quality Assessment tool. This systematic review provides a synthesis of the available evidence for childhood immunization interventions deemed effective for low SES parents or families of children ≤ 5 years of age.

SYNTHESIS

The search yielded 3317 records, of which 2975 studies met the inclusion criteria. From the 100 relevant studies, a total of 40 were included. The majority of effective and strongly rated studies synthesized consisted of multi-component interventions. Such interventions addressed access, community-based mobilization, outreach, appointment reminders, education, clinical tracking and incentives, and were language and health literacy appropriate to support low SES parents. Improving access to low SES parents was deemed effective in the vast majority of strongly rated studies. Incorrect contact information of low SES parents due to increased social mobility (i.e. household moves) rendered reminders ineffective, and therefore, updating contact information should be pursued proactively by front-line healthcare providers. In addition, plain language communication with low SES parents regarding immunization was deemed effective in improving immunization uptake.

CONCLUSION

Comprehensive multi-component interventions including improved access, appointment reminders, education and precision health communication are effective for addressing health inequities in immunization coverage amongst marginalized populations. Most low SES parents still believe that the benefits of immunization outweigh the risks.

SARS-CoV-2 vaccination intentions among mothers of children aged 9 to 12 years: a survey of the All Our Families cohort

BACKGROUND

Acceptance of a vaccine against SARS-CoV-2 is critical to achieving high levels of immunization. The objectives of this study were to understand mothers' SARS-CoV-2 vaccine intentions to explore reasons for and against SARS-CoV-2 vaccination.

METHODS

Participants from the All Our Families pregnancy longitudinal cohort whose children had reached ages 9-12 years were invited in May-June 2020 to complete a survey on the impact of COVID-19. The survey covered topics about the impact of the pandemic and included 2 specific questions on mothers' intentions to vaccinate their child against SARS-CoV-2. Current responses were linked to previously collected data, including infant vaccine uptake. Multinomial regression models were run to estimate associations between demographic factors, past vaccination status and vaccination intention. Qualitative responses regarding factors affecting decision-making were analyzed thematically.

RESULTS

The response rate was 53.8% (1321/2455). A minority of children of participants had partial or no vaccinations at age 2 (n = 200, 15.1%). A total of 60.4% of mothers (n = 798) intended to vaccinate their children with the SARS-CoV-2 vaccine, 8.6% (n = 113) did not intend to vaccinate and 31.0% (n = 410) were unsure. Lower education, lower income and incomplete vaccination history were inversely associated with intention to vaccinate. Thematic analysis of qualitative responses showed 10 themes, including safety and efficacy, long-term effects and a rushed process.

INTERPRETATION

Within a cohort with historically high infant vaccination, a third of mothers remained unsure about vaccinating their children against SARS-CoV-2. Given the many uncertainties about future SARS-CoV-2 vaccines, clear communication regarding safety will be critical to ensuring vaccine uptake.

Vaccine hesitancy among parents of preschoolers in Canada: a systematic literature review

OBJECTIVES

The purpose was to synthesize the available literature on what factors influence vaccine hesitancy of parents of preschoolers in Canada.

METHODS

Databases (e.g., CINAHL, PubMed, OVID, Proquest) were searched for relevant research articles produced between January 2009 and October 2019. Articles were required to examine vaccine uptake in children aged 0-7, in the English language, and focused within a Canadian context. Articles were excluded if they focused on uptake of the influenza vaccine and if the study population was children with chronic health conditions. A total of 367 articles were reviewed and 12 met the criteria for inclusion in this review.

SYNTHESIS

This review found that between 50% and 70% of children are completely vaccinated at 2 years old, with up to 97% having received at least one vaccine, and 2-5% receiving no vaccines. This review found that trust and access to health care providers is significantly associated with vaccine uptake, likely more important than parents' vaccine knowledge, and may compensate for challenges related to socio-economic status and family dynamics.

CONCLUSION

Vaccine programs need to be created that are accessible to all families, with an awareness of the significant impact of trust on vaccine uptake. Future research should include consistent measures of vaccine uptake, and data from First Nation communities, and should examine how increased trust between health care providers and parents of preschool children would increase vaccine uptake in Canada.

Measurement of coverage, compliance and determinants of uptake in a publicly funded rotavirus vaccination programme: a retrospective cohort study

OBJECTIVES

In June 2015, Alberta, Canada instituted a universal publicly funded rotavirus vaccination programme (Rotarix, RV1), with vaccine doses scheduled for 2 and 4 months of age. Vaccination was restricted so that infants were only allowed to receive first dose between 6 and 20 weeks of age, and second dose before eight calendar months of age. We assessed the coverage and schedule non-compliance of rotavirus vaccination for babies born between June 2015 and August 2016, that is, since the inception of the publicly funded rotavirus vaccination programme, and determined factors associated with rotavirus vaccine uptake.

DESIGN

Retrospective cohort study using linked administrative health data.

SETTING

Alberta, Canada.

PARTICIPANTS

Cohort of 66 689 children. PRIMARY AND SECONDARY OUTCOME MEASURES: (1) First and second dose rotavirus vaccination coverage, (2) percent of children non-compliant with recommended vaccine schedule and (3) adjusted ORs for factors associated with vaccination status.

RESULTS

For the 66 689 children included in the study, coverage levels for one-dose and two-dose rotavirus vaccination were 87% and 83%, respectively. In comparison, two-dose diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b vaccine coverage was 92%, despite having the same dosing schedule. Schedule non-compliance during the publicly funded programme was very low. We observed socioeconomic disparities in the uptake of the vaccine, with income, location of residence and number of children in the household all contributing to the odds of a child being vaccinated with rotavirus.

CONCLUSIONS

Compliance to the recommended rotavirus schedule was very high, suggesting that even with the restrictive rotavirus vaccine schedule, the vaccine can be delivered on-time. However, rotavirus vaccine coverage remained lower than DTaP, a similarly scheduled childhood vaccination. We also observed socioeconomic disparities in vaccine uptake. These findings raise concerns about rotavirus protection in the groups at highest risk for gastrointestinal illness, including low-income and rural populations.

Vaccine coverage of children in care of the child welfare system

OBJECTIVE

To assess vaccine coverage for a cohort of children who have been in the care of the child welfare system compared to children in the general population.

METHODS

This retrospective cohort study used population-based administrative health data for a 2008 birth cohort of children from Alberta, Canada. We assessed coverage at ages 2 (n = 44,206) and 7 (n = 42,241) for three vaccines with different administration schedules for children in care (at any period before the age of assessment) and those who had never been in care, comparing them using risk differences and relative risks (RRs). We similarly assessed coverage for children not in care who shared characteristics of children in care.

RESULTS

At age two, vaccination coverage for children in care ranged from 54.3% to 81.4%, depending on vaccine. In comparison, coverage for those not in care ranged from 74.2% to 87.4%. At age seven, coverage for children in care ranged from 53.1% to 65.3%, compared to 76.6% to 83.4% for those not in care. For all vaccines at both ages, the risk for being under-vaccinated was higher for children in care (e.g., diphtheria, pertussis, tetanus, polio, Haemophilus influenzae type b at age 7: RR 2.01, 95% confidence interval [CI] (1.74-2.32). Even for children not in care who had characteristics similar to children in care, we found children in care had lower coverage.

CONCLUSION

Children in care have consistently lower vaccine coverage than children not in care. Policies and practices should promote optimal access to vaccination for these children.

Are we speaking the same language? an argument for the consistent use of terminology and definitions for childhood vaccination indicators

Vaccination indicators are used to measure the health status of individuals or populations and to evaluate the effectiveness of vaccination programs or policies. Ensuring that vaccination indicators are clearly and consistently defined is important for effective communication of outcomes, accurate program evaluation, and comparison between different populations, times, and contexts. The purpose of this commentary is to describe commonly used vaccination indicators and to highlight inconsistencies in how childhood vaccine researchers use and define these terms. The indicators we describe are vaccine coverage, uptake, and rate; vaccination status, initiation, and completion; and up-to-date, timely, partial, and incomplete vaccination. We conclude that many vaccination indicators are not explicitly defined within published research studies and/or are used quite differently across studies. We also note that the choice of indicator in a given study is often driven by program or vaccine specific factors, may be constrained by data availability, and should be chosen to best reflect the outcome of interest. We conclude that the use of consistent language and definitions would promote more effective communication of research findings. We also propose some standardized definitions for common indicators, with the goal of provoking discussion and debate on the issue.

The impact of time since vaccination and study design on validity in parental recall of childhood vaccination status in the All Our Families cohort

INTRODUCTION

Parental reporting of childhood vaccination status is often used for policy and program evaluation and research purposes. Many factors can bias parental reporting of childhood vaccination status, however, to our knowledge, no analysis has assessed whether time since vaccination impacts reporting accuracy. Therefore, using the Calgary electronic vaccine registry (PHANTIM) as the gold standard, we aimed to test the accuracy of parental reporting of childhood vaccination status at three different time-points since vaccination.

METHODS

The All Our Families (AOF) cohort study asked parents to report their child's 2, 4, 6, 12 and 18 month vaccines (vaccination time-point) on questionnaires given when the child was 1, 2 and 3 years of age (survey time-point). We linked the AOF parental reporting of vaccination status to the PHANTIM registry and calculated the percent agreement and difference in coverage estimates between PHANTIM and AOF at each vaccination and survey time-point combination. Furthermore, we measured the sensitivity and specificity, and negative (NPV) and positive predictive values (PPV) of parental vaccine recall across time.

RESULTS

AOF parent reports of coverage rates were consistently higher than the PHANTIM estimates. While we saw significant differences in percent agreement for certain vaccination time-points, we saw no consistent directional difference by survey time-point, suggesting that parental accuracy did not change with time. We found a uniformly high sensitivity across all vaccination and survey time-points, and no consistent patterns in the specificity, PPV and NPV results.

CONCLUSION

Time since vaccination may not be the most important consideration when designing and implementing a vaccination survey. Other factors that may contribute to the bias associated with parental reporting of vaccination status include the complexity of the vaccine schedule, schedule changes over time, and the wording and structure of the questionnaires.

Determinants of under-immunization and cumulative time spent under-immunized in a Quebec cohort

BACKGROUND

Under-immunization refers to a state of sub-optimal protection against vaccine preventable diseases. Vaccine coverage for age may not capture intentional or non-intentional spacing of vaccines in the recommended provincial immunization guidelines. We aimed to identify factors associated with coverage and under-immunization and to determine the number of days during which children were under-immunized during their first 24months of life.

METHODS

Secondary analysis of children ≤3years recruited through active surveillance for gastroenteritis from three Quebec pediatric emergency departments from 2012 to 2014. Vaccination status for children at least 24months of age was determined using provincial immunization guidelines. Cumulative days under-immunized were calculated for DTaP-VPI-Hib, PCV, MMR, and Men-C-C. Factors associated with up-to-date (UTD) status at 24months of life and for under-immunization ≥6months were analyzed using logistic regression.

RESULTS

Of 246 eligible children, 180 (73%) were UTD by 24months of life. The mean cumulative days under-immunized for MMR was 107days, for PCV 209days, for Men-C-C 145days, and for DTaP-VPI-Hib 227days. Overall, 149 children (60%) experienced delay for at least 1 vaccine. Factors associated with both an UTD status at 24months and concurrently associated with being under-immunization ≥6months, included timely initiation of immunization (OR=5.85; 95% CI: 2.80-12.22) and (OR=0.13; 95% CI: 0.07-0.24), failure to co-administer 18-month vaccines (OR=0.15; 95% CI: 0.10-0.21) and (OR=3.29; 95% CI: 2.47-4.39), and having a household with ≥3 children under 18years ((OR=0.50; 0.28-0.86) and (OR=2.99; 1.45-6.22), respectively.

CONCLUSION

Paired with an unexpected low level of coverage at 24months of life, the majority of our cohort also experienced a state of under-immunization for a least one vaccine. Estimates of coverage do not capture intentional or non-intentional gaps in protection from vaccine preventable illnesses. Timely preventive care should be prioritized.

Timeliness and completeness of routine childhood vaccinations in children by two years of age in Alberta, Canada

OBJECTIVES

Assessing timeliness and completeness of vaccine administration is important for evaluating the effectiveness of immunization programs. Few studies have reported timeliness, particularly in Canada. The objective of this study was to examine timeliness of the receipt of vaccination for each routine childhood recommended vaccine by 24 months of age among children in a community-based pregnancy cohort in Calgary, Alberta.

METHODS

Survey data from a community-based pregnancy cohort in Alberta were linked to Public Health vaccination records of children (n = 2763). The proportion of children receiving early, timely, delayed, or no vaccination was calculated. A dose was considered early if it was administered before the recommended age in days as per the vaccination schedule, timely if administered at any time from start of recommended age in days to age in days when delay counts were initiated, and delayed if it was administered on or after age in days when delay counts were initiated. Series completion rates were also calculated.

RESULTS

For multi-dose vaccines, over 80% of children had timely doses at 2, 4 and 6 months. By 12 months, this proportion decreased to 65% (95% CI: 63%-66%) for meningococcal conjugate group C, 61% (95% CI: 59%-62%) for measles antigen-containing vaccines and 64% (95% CI: 62%-65%) for varicella antigen-containing vaccines. At 18 months, only 55% (95% CI: 53%-56%) of the children had a timely 4th dose of diphtheria, acellular pertussis, tetanus, polio, and Haemophilus influenzae type b vaccine. Eventual series completion rate for all recommended vaccines was 77% (95% CI: 75%-79%).

CONCLUSION

The timeliness and completeness of routine childhood vaccination in preschool children in this community-based pregnancy cohort is lower than provincial targets. Data on timeliness of vaccination can inform further work on barriers and enablers to vaccination in order to meet provincial targets.

Vaccine shot-limiting: Estimating the prevalence, indicators, and impact on vaccination status - Michigan, 2012

BACKGROUND

Concerns regarding vaccine safety and pain have prompted certain parents to limit the number of shots their child receives per visit. We estimated the prevalence of shot-limited children in Michigan, described their characteristics, assessed whether shot-limited children were up-to-date on recommended vaccinations, and investigated possible intervention points for vaccination education.

METHODS

We analyzed vaccination registry and birth record data of children born in Michigan during 2012 who had ⩾2 vaccination visits, with ⩾1 visits after age 5months. Shot-limited was defined as receiving ⩽2 shots at all visits through age 24months. Nonlimited children received >2 shots at ⩾1 visits. Up-to-date vaccination was based on receipt of a seven-vaccine series and was determined at ages 24months and 35months. Risk ratios (RR) were calculated using risk regression.

RESULTS

Of 101,443 children, a total of 2,967 (3%) children were shot-limited. Mothers of shot-limited children were more likely to be white (RR: 1.2; 95% confidence interval [CI]: 1.2-1.2), college graduate (RR: 1.9; 95% CI: 1.9-2.0), and married (RR: 1.5; 95% CI: 1.5-1.5). Compared with nonlimited children, shot-limited children were more likely to be born in a nonhospital setting (RR: 11.7; 95% CI: 9.4-14.6) and have a midwife attendant (RR: 1.9; 95% CI: 1.7-2.1). Shot-limited children were less likely to be up-to-date on recommended vaccinations (RR: 0.2; 95% CI: 0.2-0.3); this association was stronger for those with a midwife birth attendant (RR: 0.1; 95% CI: 0.1-0.2) rather than a medical doctor (RR: 0.3; 95% CI: 0.2-0.3).

CONCLUSIONS

Shot-limited children are less likely to be up-to-date on vaccinations, possibly leading to increased risk for vaccine-preventable diseases. This association was stronger for those with a midwife birth attendant. This analysis should prompt targeted education, such as to midwives, concerning risks associated with shot-limiting behavior.

Examination of a prenatal syphilis screening program, Alberta, Canada: 2010-2011

OBJECTIVES

In 2009, due to increasing congenital syphilis rates, prenatal syphilis tests (PST) at both mid-gestation and delivery were added to first trimester prenatal screening in the province of Alberta. We sought to determine the proportion of mothers who had all three recommended PSTs during this period and to identify factors associated with incomplete PST.

METHODS

A cohort of all pregnancies resulting in a live or stillborn infant in Alberta for 2010 and 2011 was developed from Vital Statistics and linked with prenatal screening data to determine the number and timing of PSTs for pregnant women. The proportion of women who had PSTs at the three recommended time points in pregnancy and associated correlates were identified using basic statistics and logistic regressions.

RESULTS

Of 99,609 pregnancies, 20.7% had all three PSTs at the recommended time points. Overall, 98.5% (98,162) had at least one PST, 1.5% only had PST at delivery and 1.5% had no PST performed. Independent risk factors for not having the three recommended PSTs included First Nations status (adjusted odds ratio [AOR]: 1.78 [95% CI: 1.62-1.96]), rural remote residence (AOR 3.61 [95% CI: 3.10-4.20]) and sole use of a midwife for prenatal care (AOR 13.70 [95% CI: 9.20-20.39]).

CONCLUSIONS

Nearly all pregnant women in Alberta received a PST at least once during their pregnancy, however far fewer received PSTs at the recommended time points. Interventions that target those who are less likely to be prenatally screened may help to ensure that pregnant women get early and appropriate care for syphilis during pregnancy.