Patterns in COVID-19 vaccination among children aged 5-11 years in Alberta, Canada: Lessons for future vaccination campaigns.

Objectives: In Alberta, Canada, the COVID-19 vaccination program for children aged 5-11 years was launched on November 26, 2021. Our objectives were to determine the cumulative vaccine coverage, stratified by age, during the first thirteen months of vaccine availability, and investigate factors associated with vaccine uptake. Study design: This retrospective cohort study used population-based administrative health data. Methods: We determined cumulative vaccine coverage among 5-11 year olds, stratified by year of age, during the first thirteen months of vaccine availability and used a modified Poisson regression to evaluate factors associated with vaccine uptake. Results: Of 377,103 eligible children, 44.8 % (n = 168,761) received one or more doses of COVID-19 vaccine during the study period (9.7 % received only one dose, while 35.1 % received 2 doses). Almost 90 % of initial doses were received within the first two months of vaccine availability. We found a step-wise relationship between increasing child age and higher vaccine coverage. Conclusions: Plateaued vaccine uptake indicates a need to adapt programmatic efforts to encourage parents to act on positive vaccination intentions, and reach the large contingent of parents who have reported that they remain undecided. In order to promote vaccine uptake, messaging around vaccine safety and need should be tailored to child age, rather than uniformly applied across the 5-11 year age range.

Effectiveness of hospital-based strategies for improving childhood immunization coverage: A systematic review.

BACKGROUND: Hospital settings represent an opportunity to offer and/or promote childhood vaccination. The purpose of the systematic review was to assess the effectiveness of different hospital-based strategies for improving childhood vaccination coverage. METHODS: A systematic search of multiple bibliographic databases, thesis databases, and relevant websites was conducted to identify peer-reviewed articles published up to September 20, 2021. Articles were included if they evaluated the impact of a hospital (inpatient or emergency department)-based intervention on childhood vaccination coverage, were published in English or French, and were conducted in high-income countries. High quality studies were included in a narrative synthesis. RESULTS: We included 25 high quality studies out of 7,845 unique citations. Studies focused on routine, outbreak, and influenza vaccines, and interventions included opportunistic vaccination (i.e. vaccination during hospital visit) (n = 7), patient education (n = 2), community connection (n = 2), patient reminders (n = 2), and opportunistic vaccination combined with patient education and/or reminders (n = 12). Opportunistic vaccination interventions were generally successful at improving vaccine coverage, though results ranged from no impact to vaccinating 71 % of eligible children with routine vaccines and 9-61 % of eligible children with influenza vaccines. Interventions that aimed to increase vaccination after hospital discharge (community connection, patient education, reminders) were less successful. CONCLUSIONS: Some interventions that provide vaccination to children accessing hospitals improved vaccine coverage; however, the baseline coverage level of the population, as well as implementation strategies used impact success. There is limited evidence that interventions promoting vaccination after hospital discharge are more successful if they are tailored to the individual.

Inclusion of intersectionality in studies of immunization uptake in Canada: A scoping review.

INTRODUCTION: Intersectionality refers to the interconnectedness of various social locations creating unique experiences for individuals and groups, in the context of systems of privilege and oppression. As part of immunization coverage research, intersectionality allows healthcare professionals and policymakers to become aware of the constellation of characteristics contributing to low vaccine uptake. The objective of this study was to examine the application of intersectionality theory or concepts, and the appropriate use of sex and gender terminology, in Canadian immunization coverage research. MATERIALS AND METHODS: The eligibility criteria for this scoping review included English or French language studies on immunization coverage among Canadians of all ages. Six research databases were searched without date restrictions. We searched provincial and federal websites, as well as the Proquest Dissertations and Theses Global database for grey literature. RESULTS: Of 4725 studies identified in the search, 78 were included in the review. Of these, 20 studies included intersectionality concepts, specifically intersections of individual-level characteristics influencing vaccine uptake. However, no studies explicitly used an intersectionality framework to guide their research. Of the 19 studies that mentioned "gender", 18 had misused this term, conflating it with "sex". CONCLUSIONS: Based on our findings, there is an evident lack of intersectionality framework utilization in immunization coverage research in Canada, as well as misuse of the terms "gender" and "sex". Rather than only focusing on discrete characteristics, research should explore the interaction between numerous characteristics to better understand the barriers to immunization uptake in Canada.

Transition to endemic: acceptance of additional COVID-19 vaccine doses among Canadian adults in a national cross-sectional survey.

BACKGROUND: Additional doses of COVID-19 vaccine have been proposed as solutions to waning immunity and decreased effectiveness of primary doses against infection with new SARS-CoV-2 variants. However, the effectiveness of additional vaccine doses relies on widespread population acceptance. We aimed to assess the acceptance of additional COVID-19 vaccine doses (third and annual doses) among Canadian adults and determine associated factors. METHODS: We conducted a national, cross-sectional online survey among Canadian adults from October 14 to November 12, 2021. Weighted multinomial logistic regression analyses were used to identify sociodemographic and health-related factors associated with third and annual dose acceptance and indecision, compared to refusal. We also assessed influences on vaccine decision-making, and preferences for future vaccine delivery. RESULTS: Of 6010 respondents, 70% reported they would accept a third dose, while 15.2% were undecided. For annual doses, 64% reported acceptance, while 17.5% were undecided. Factors associated with third dose acceptance and indecision were similar to those associated with annual dose acceptance and indecision. Previous COVID-19 vaccine receipt, no history of COVID-19 disease, intention to receive an influenza vaccine, and increasing age were strongly associated with both acceptance and indecision. Chronic illness was associated with higher odds of acceptance, while self-reported disability was associated with higher odds of being undecided. Higher education attainment and higher income were associated with higher odds of accepting additional doses. Minority first language was associated with being undecided about additional doses, while visible minority identity was associated with being undecided about a third dose and refusing an annual dose. All respondents reported government recommendations were an important influence on their decision-making and identified pharmacy-based delivery and drop-in appointments as desirable. Co-administration of COVID-19 and influenza vaccines was viewed positively by 75.5% of the dose 3 acceptance group, 12.3% of the undecided group, and 8.4% of the refusal group. CONCLUSIONS: To increase acceptance, targeted interventions among visible minority and minority language populations, and those with a disability, are required. Offering vaccination at pharmacies and through drop-in appointments are important to facilitate uptake, while offering COVID-19/influenza vaccine co-administration may have little benefit among those undecided about additional doses.

Using Health Economics to Inform Immunization Policy Across All Levels of Government.

Publicly funded immunization programs have grown in both complexity and scope, resulting in increased costs and more complex programmatic decision making. Economic evaluations can provide crucial information to support informed decision making. While very few countries have National Immunization Technical Advisory Groups that analyze economic information, many have started to develop processes for this purpose. Since these guidelines are being developed at the national level, we propose that regional jurisdictions, especially those responsible for healthcare (e.g., provinces, territories, states), need clear processes for incorporating this information into their immunization decision making and program implementation. We interviewed Canadian vaccine experts involved in provincial vaccine policy decision making to identify current practices, perceptions, and recommendations around incorporating economic analysis into that process. Based on these interviews, we make five recommendations: (1) economic evidence should be routinely incorporated into the decision making process; (2) economic experts should sit on, or be available to, regional advisory committees; (3) efforts should be made to build on regional expertise by increasing educational opportunities on economic evaluation; (4) processes should include guidelines for when economic analysis is not required; and (5) clarification on the role of regional advisory groups in economic analysis is needed in relation to national expertise. The information presented here provides a starting point for regional health policy experts and decision makers to work collaboratively with national partners to create transparent and effective approaches to incorporating economic analysis into vaccine decision making.

COVID-19 vaccine uptake and intention during pregnancy in Canada.

OBJECTIVE: To investigate COVID-19 vaccine uptake and intent among pregnant people in Canada, and determine associated factors. METHODS: We conducted a national cross-sectional survey among pregnant people from May 28 through June 7, 2021 (n = 193). Respondents completed a questionnaire to determine COVID-19 vaccine acceptance (defined as either received or intend to receive a COVID-19 vaccine during pregnancy), factors associated with vaccine acceptance, and rationale for accepting/not accepting the vaccine. RESULTS: Of 193 respondents, 57.5% (n = 111) reported COVID-19 vaccine acceptance. Among those who did not accept the vaccine, concern over vaccine safety was the most commonly cited reason (90.1%, n = 73), and 81.7% (n = 67) disagreed with receiving a vaccine that had not been tested in pregnant people. Confidence in COVID-19 vaccine safety (aOR 16.72, 95% CI: 7.22, 42.39), Indigenous self-identification (aOR 11.59, 95% CI: 1.77, 117.18), and employment in an occupation at high risk for COVID-19 exposure excluding healthcare (aOR 4.76, 95% CI: 1.32, 18.60) were associated with vaccine acceptance. Perceived personal risk of COVID-19 disease was not associated with vaccine acceptance in the multivariate model. CONCLUSION: Vaccine safety is a primary concern for this population. Safety information should be communicated to this population as it emerges, along with clear messaging on the benefits of vaccination, as disease risk is either poorly understood or poorly valued in this population.

RéSUMé: OBJECTIF: Examiner l'intention de se faire vacciner contre la COVID-19 et l'adoption du vaccin anti-COVID-19 chez les personnes enceintes au Canada, et déterminer les facteurs associés. MéTHODE: Du 28 mai au 7 juin 2021, nous avons mené un sondage transversal national auprès de personnes enceintes (n = 193). Les répondantes ont rempli un questionnaire pour nous permettre de déterminer l'acceptation du vaccin contre la COVID-19 (définie comme le fait d'avoir reçu ou l'intention de recevoir un vaccin anti-COVID-19 durant la grossesse), les facteurs associés à l'acceptation du vaccin et les motifs d'acceptation ou de refus du vaccin. RéSULTATS: Sur les 193 répondantes, 57,5 % (n = 111) ont dit accepter le vaccin contre la COVID-19. Chez celles qui n'acceptaient pas le vaccin, l'inquiétude face à son innocuité était la raison la plus souvent citée (90,1 %, n = 73), et 81,7 % (n = 67) n'acceptaient pas de recevoir un vaccin qui n'avait pas été testé sur des personnes enceintes. La confiance en l'innocuité du vaccin anti-COVID-19 (RCa 16,72, IC de 95 % : 7,22, 42,39), l'auto-identification en tant que personne autochtone (RCa 11,59, IC de 95 % : 1,77, 117,18) et l'emploi dans une profession à risque élevé d'exposition à la COVID-19, sauf les soins de santé (RCa 4,76, IC de 95 % : 1,32, 18,60) étaient associés à l'acceptation du vaccin. Le risque personnel perçu de tomber malade de la COVID-19 n'était pas associé à l'acceptation du vaccin dans notre modèle multivarié. CONCLUSION: L'innocuité du vaccin est une préoccupation majeure dans cette population. Des informations sur l'innocuité devraient être communiquées aux personnes enceintes au fur et à mesure qu'elles sont connues, ainsi que des messages clairs sur les avantages de la vaccination, car le risque de maladie est soit mal compris, soit déconsidéré dans cette population.

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.

The impact of varicella vaccination on paediatric herpes zoster epidemiology: a Canadian population-based retrospective cohort study.

The impact of universal varicella vaccination on herpes zoster (HZ) risk in unvaccinated and vaccinated children, and its long-term influence on HZ epidemiology, remains unknown. We conducted a retrospective cohort study using population-based administrative health data for children born between 1993 and 2018 (n = 924,124). We calculated age-specific cumulative HZ incidence rates by vaccination status for cohorts born before (1993-1999) and after (2000-2018) programme implementation; results were used to calculate relative risk of HZ by age group, vaccination status and vaccine availability period. Annual HZ incidence rates were calculated for 1993-2018. HZ risk was higher among unvaccinated children compared to vaccinated children across age groups; 64% higher before universal vaccination (RR: 0.36, 95% CI: 0.33, 0.39), and 32% higher after universal vaccination (RR: 0.68, 95% CI: 0.64, 0.73). Among unvaccinated children, HZ risk was 60% lower after vaccine programme implementation (RR: 0.40, 95% CI: 0.38, 0.43). Two-dose receipt corresponded with a 41% lower risk of HZ compared to one-dose receipt (RR: 0.59, 95% CI: 0.53, 0.65). Crude annual HZ incidence rates declined 64% after programme implementation, with decreases observed across age groups. Universal varicella vaccination programme implementation corresponds to decreased paediatric HZ incidence across age groups, in both vaccinated and unvaccinated individuals. Results from this study can be used to help inform varicella vaccination programme decision-making in other countries.

A comparision of laboratory and field based determinations of molecular diffusion coefficients in a low permeability geologic medium.

Molecular diffusion is the dominant transport mechanism for contaminants in many saturated clay-rich aquitards. The effective coefficient of diffusion (Da) is traditionally determined by conducting laboratory tests on cm-scale core samples that may not be representative of the bulk geologic formation. Here we conducted the first long-term field based in situ diffusion experimentto compare the effect of experimental scale (5 x 10(-5) m3 in the diffusion cells and (5-20) x 10(-2) m3 in the in situ experiments) on De values for clay-rich aquitards. Using a conservative tracer (deuterium), our testing shows De values estimated from in situ testing ((2.5-3.5) x 10(-10) m2 s(-1)) are similar but lower than the average De values measured in the laboratory (4 x 10(-10) m2 s(-1)). The difference was attributed to greater porosity values in the laboratory samples resulting from core barrel extrusion and sample swelling. With representative core sampling and care, laboratory-based diffusion testing remains a viable method to assess solute transport mechanisms in clay aquitards.