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

Confidence and barriers: Analysis of factors associated with timely routine childhood vaccination in Canada during the COVID-19 pandemic

Routine childhood vaccination is a crucial component of public health in Canada and worldwide. To facilitate catch-up from the global decline in routine vaccination caused by the COVID-19 pandemic, and toward the ongoing pursuit of coverage goals, vaccination programs must understand barriers to vaccine access imposed or exacerbated by the pandemic. We conducted a regionally representative online survey in January 2023 including 2036 Canadian parents with children under the age of 18. We used the COM-B model of behaviour to examine factors influencing vaccination timeliness during the pandemic. We assessed Capability with measures of vaccine understanding and decision difficulty, and Motivation with a measure of vaccine confidence. Opportunity was assessed through parents' self-reported experience with barriers to vaccination. Twenty-four percent of surveyed parents reported having missed or delayed one of their children's scheduled routine vaccinations since the beginning of the pandemic, though most parents reported having either caught up or the intention to catch up soon. In the absence of opportunity barriers, motivation was associated with timely vaccination for children aged 0-4 years (aOR = 1.81, 95 % CI: 1.14-2.84). However, experience with one or more opportunity barriers, particularly clinic closures and difficulties getting an appointment, eliminated this relationship, suggesting perennial and new pandemic-associated barriers are a critical challenge to vaccine coverage goals in Canada.

Community Engagement in Vaccination Promotion: Systematic Review and Meta-Analysis

BACKGROUND

Community engagement plays a vital role in global immunization strategies, offering the potential to overcome vaccination hesitancy and enhance vaccination confidence. Although there is significant backing for community engagement in health promotion, the evidence supporting its effectiveness in vaccination promotion is fragmented and of uncertain quality.

OBJECTIVE

This review aims to systematically examine the effectiveness of different contents and extent of community engagement for promoting vaccination rates.

METHODS

This study was performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A comprehensive and exhaustive literature search was performed in 4 English databases (PubMed, Embase, Web of Science, and Cochrane Library) and 2 Chinese databases (CNKI and Wan Fang) to identify all possible articles. Original research articles applying an experimental study design that investigated the effectiveness of community engagement in vaccination promotion were eligible for inclusion. Two reviewers independently performed the literature search, study selection, quality assessment, and data extraction. Discrepancies were resolved through discussion, with the arbitration of a third reviewer where necessary.

RESULTS

A total of 20 articles out of 11,404 records from 2006 to 2021 were retrieved. The studies used various designs: 12 applied single-group pre-post study designs, 5 were cluster randomized controlled trials (RCTs), and 3 were non-RCTs. These studies targeted multiple vaccines, with 8 focusing on children's immunization, 8 on human papillomavirus vaccine, 3 on hepatitis B virus vaccine, and 1 on COVID-19 vaccine. The meta-analysis revealed significant increases in vaccination rates both in pre-post comparison (rate difference [RD] 0.34, 95% CI 0.21-0.47, I2=99.9%, P<.001) and between-group comparison (RD 0.18, 95% CI 0.07-0.29, I2=98.4%, P<.001). The meta-analysis revealed that participant recruitment had the largest effect size (RD 0.51, 95% CI 0.36-0.67, I2=99.9%, P<.001), followed by intervention development (RD 0.36, 95% CI 0.23-0.50, I2=100.0%, P<.001), intervention implementation (RD 0.35, 95% CI 0.22-0.47, I2=99.8%, P<.001), and data collection (RD 0.34, 95% CI 0.19-0.50, I2=99.8%, P<.001). The meta-analysis indicated that high community engagement extent yielded the largest effect size (RD 0.49, 95% CI 0.17-0.82, I2=100.0%, P<.001), followed by moderate community engagement extent (RD 0.45, 95% CI 0.33-0.58, I2=99.6%, P<.001) and low community engagement extent (RD 0.15, 95% CI 0.05-0.25, I2=99.2%, P<.001). The meta-analysis revealed that "health service support" demonstrated the largest effect sizes (RD 0.45, 95% CI 0.25-0.65, I2=99.9%, P<.001), followed by "health education and discussion" (RD 0.39, 95% CI 0.20-0.58, I2=99.7%, P<.001), "follow-up and reminder" (RD 0.33, 95% CI 0.23-0.42, I2=99.3%, P<.001), and "social marketing campaigns and community mobilization" (RD 0.24, 95% CI 0.06-0.41, I2=99.9%, P<.001).

CONCLUSIONS

The results of this meta-analysis supported the effectiveness of community engagement in vaccination promotion with variations in terms of engagement contents and extent. Community engagement required a "fit-for-purpose" approach rather than a "one-size-fits-all" approach to maximize the effectiveness of vaccine promotion.

TRIAL REGISTRATION

PROSPERO CRD42022339081; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=339081.

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.

Safety and immunogenicity of co-administered meningococcal serogroup B (4CMenB) vaccine: A literature review

The four-component meningococcal serogroup B vaccine (4CMenB) is indicated for the prevention of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup B. Co-administering 4CMenB with other vaccines may improve vaccine uptake provided that the safety and immunogenicity of either are not affected. Published literature on the immunogenicity and reactogenicity of 4CMenB co-administered with other routine childhood and adulthood vaccines was reviewed. From 282 publications identified, data were collated from 10 clinical studies, 3 real-world studies, and 3 reviews. The evidence showed that 4CMenB co-administration is not associated with significant safety concerns or clinically relevant immunological interferences. The increased reactogenicity (e.g., fever) associated with 4CMenB co-administration can be adequately managed with prophylactic paracetamol in children. Thus, 4CMenB co-administration has the potential to maximize vaccine coverage and improve protection against IMD globally.

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.

Determinants of incomplete vaccination in children at age two in France: results from the nationwide ELFE birth cohort

Incomplete vaccination in the pediatric population is a growing public health issue in high-income countries, but its determinants are poorly understood. Their identification is necessary to design target actions that can improve vaccination uptake. Our aim was to assess the determinants of incomplete vaccination in two-year-old children in France. Among the 18,329 children included in the 2011 ELFE French nationwide population-based birth cohort, we selected those for whom vaccination status was available at age two years. Incomplete vaccination was defined as ≥ 1 missing dose of recommended vaccines. Potential determinants of incomplete vaccination were identified by using logistic regression, taking into account attrition and missing data. Of the 5,740 (31.3%) children analyzed, 46.5% (95% confidence interval [CI] 44.7-48.0) were incompletely vaccinated. Factors independently associated with incomplete vaccination were having older siblings (adjusted odds ratio 1.18, 95% CI [1.03-1.34] and 1.28 [1.06-1.54] for one and ≥ 2 siblings, respectively, vs. 0), residing in an isolated area (1.92 [1.36-2.75] vs. an urban area), parents not following health recommendations or using alternative medicines (1.81 [1.41-2.34] and 1.23 [1.04-1.46], respectively, vs. parents confident in institutions and following heath recommendations), not being visited by a maternal and child protection service nurse during the child's first two months (1.19 [1.03-1.38] vs. ≥ 1 visit), and being followed by a general practitioner (2.87 [2.52-3.26] vs. a pediatrician).

CONCLUSIONS

Incomplete vaccination was highly prevalent in the studied pediatric population and was associated with several socio-demographic, parental, and healthcare service characteristics. These findings may help in designing targeted corrective actions.

WHAT IS KNOWN

• Incomplete vaccination in the pediatric population is a growing public health issue in high-income countries. • The partial understanding of the determinants of incomplete vaccination precludes the design of effective targeted corrective actions.

WHAT IS NEW

• High prevalence of incomplete vaccination at age two years in France. • Incomplete vaccination was independently associated with several socio-demographic, parental, and healthcare service characteristics.

Delay in childhood vaccinations during the COVID-19 pandemic

OBJECTIVES

In many jurisdictions, routine medical care was reduced in response to the COVID-19 pandemic. The objective of this study was to determine whether the frequency of on-time routine childhood vaccinations among children age 0-2 years was lower following the COVID-19 declaration of emergency in Ontario, Canada, on March 17, 2020, compared to prior to the pandemic.

METHODS

We conducted a longitudinal cohort study of healthy children aged 0-2 years participating in the TARGet Kids! primary care research network in Toronto, Canada. A logistic mixed effects regression model was used to determine odds ratios (ORs) for delayed vaccination (> 30 days vs. ≤ 30 days from the recommended date) before and after the COVID-19 declaration of emergency, adjusted for confounding variables. A Cox proportional hazards model was used to explore the relationship between the declaration of emergency and time to vaccination.

RESULTS

Among 1277 children, the proportion of on-time vaccinations was 81.8% prior to the COVID-19 declaration of emergency and 62.1% after (p < 0.001). The odds of delayed vaccination increased (odds ratio = 3.77, 95% CI: 2.86-4.96), and the hazard of administration of recommended vaccinations decreased after the declaration of emergency (hazard ratio = 0.75, 95% CI: 0.60-0.92). The median vaccination delay time was 5 days (95% CI: 4-5 days) prior to the declaration of emergency and 17 days (95% CI: 12-22 days) after.

CONCLUSION

The frequency of on-time routine childhood vaccinations was lower during the first wave of the COVID-19 pandemic. Sustained delays in routine vaccinations may lead to an increase in rates of vaccine-preventable diseases.

Gaps in knowledge about the vaccine coverage of immunocompromised children: a scoping review

Immunocompromised children are at increased risk of severe illness from vaccine-preventable infections. However, inadequate vaccine coverage remains a concern. This scoping review sought to determine the current state of knowledge regarding vaccine coverage of immunocompromised children. Bibliographic databases were searched for primary research from any year. Data were analyzed quantitatively and narratively. Ninety-seven studies met inclusion criteria. The most commonly studied vaccines were pneumococcal (n = 46), influenza (n = 44), diphtheria/tetanus/pertussis/poliomyelitis/Haemophilus influenzae type B/hepatitis B-containing (n = 36), and measles- and/or mumps- and/or rubella-containing (n = 29). Immunocompromising conditions studied included cancer/stem cell transplants (n = 24), solid organ transplants (n = 23), sickle cell disease (n = 21), immunosuppressive therapy (n = 14), human immunodeficiency virus (n = 12), splenectomy (n = 4), and primary immunodeficiency (n = 2). As more children are treated with immunosuppressive therapies, it is critical to identify whether they are being appropriately vaccinated for age and condition. We identified gaps in the current state of knowledge for specific vaccine types in specific immunocompromised populations.

Invasive pneumococcal disease in Canada 2010-2017: The role of current and next-generation higher-valent pneumococcal conjugate vaccines

BACKGROUND

In 2010-2011, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced the 7- or 10-valent vaccine (PCV7 and PCV10, respectively) in pediatric immunization programs across Canada. For adults aged ≥65 years, the 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been publicly funded for several decades; PCV13 funding was not recommended in this population, partly due to expected ongoing vaccine-serotype disease decline stemming from herd effects of the pediatric program. Higher-valent PCVs (ie, 15- and 20-valent PCVs [PCV15 and PCV20, respectively]) currently in development may become available in Canada in the coming years.

METHODS

Using the National Microbiology Laboratory surveillance reports, annual case counts and serotype distribution of invasive pneumococcal disease (IPD) from 2010 to 2017 in Canada were examined to assess the impact of existing programs on PCV13-serotype IPD and determine the proportion of IPD that can potentially be prevented by current and forthcoming higher-valent PCVs.

RESULTS

The percentages of PCV13-serotype IPD decreased from 55% [1492/2708] in 2010 to 30% [902/3006] in 2017 in all age groups combined, including a decline from 67% [221/331] to 18% [40/219] in children aged <5 years and from 50% [487/967] to 23% [287/1238] in adults aged ≥65 years. Overall, IPD cases declined mainly before 2014 and have plateaued since then. In 2017, PCV15- and PCV20-serotypes (inclusive of PCV13 serotypes) accounted for 42% and 58% of IPD cases, respectively, in all ages.

CONCLUSIONS

In Canada, publicly funded pediatric PCV13 use was associated with large declines in IPD due to vaccine serotypes. Substantial residual PCV13-serotype IPD proportions observed among all ages imply limits to indirect protection afforded by the pediatric PCV13 program at the current uptake level and suggest the adult PPSV23 program alone is insufficient. Higher-valent PCVs have the potential to address a substantial proportion of remaining IPD cases among all age groups.

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.

Infant, maternal and demographic predictors of delayed vaccination: A population-based cohort study

BACKGROUND

Receiving vaccines at or close to their due date (vaccination timeliness) is a now key measure of program performance. However, studies comprehensively examining predictors of delayed infant vaccination are lacking. We aimed to identify predictors of short and longer-term delays in diphtheria-tetanus-pertussis (DTP) vaccination by dose number and ethnicity.

METHODS

Perinatal, notification, death and immunisation databases were linked for 1.3 million births in 2000-11 from two Australian states (Western Australia and New South Wales), with follow-up data until 2013. Ordinal logistic regression was used to estimate adjusted relative risks (RR) by degree of delay. Separate models were constructed for each vaccine dose and for Aboriginal and non-Aboriginal children.

RESULTS

Each dose-specific cohort included at least 49,000 Aboriginal and 1.1 million non-Aboriginal children. Delayed receipt was more common among Aboriginal than non-Aboriginal children (eg for the first dose of DTP [DTP1] 19.4 v 8.1%). Risk factors for delayed vaccination were strongest for DTP1, and delayed receipt of DTP1 was a key driver of subsequent delays; every week DTP1 was delayed was associated with a 1.6 to 2-fold increased risk of delayed DTP2 receipt. For DTP1, ≥3 previous pregnancies (the only factor more strongly associated with longer than shorter delays; RR ≥5 compared to no previous pregnancies), and children born to mothers <20 years of age (RR ≥2 compared to ≥35 years) were at highest risk of delay. Other independent predictors were prematurity, maternal smoking during pregnancy, and being born in Western Australia (if Aboriginal) or another country in the Oceania region.

CONCLUSION

The sub-populations at risk for delayed vaccination we have identified are likely generalisable to other high-income settings. Measures to improve their dose 1 timeliness, particularly for children with older siblings, are likely to have significant flow-on benefits for timeliness of later doses.