Abstract
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.
Keywords: Vaccine coverage, School children, COVID-19
1. Introduction
The success of childhood vaccination programs is dependent on the willingness of parents to obtain vaccines for their children, supported by acceptable and equitable vaccination delivery. Attitudes toward vaccination are commonly identified on a continuum, ranging from active demand for vaccines to complete refusal of all vaccines [1]. The large middle ground of this continuum consists of a varied group of individuals who are unsure about some or all vaccines, and may or may not refuse or delay vaccinations for their children [1,2]. Previous studies explored parental intentions toward COVID-19 vaccination for their children, in anticipation of vaccine offerings. A global pooled estimate compiled in December 2021 reported that approximately 60 % of parents intended to vaccinate their children, while approximately 22.9 % intended to refuse vaccination [3]. However, results varied widely, and studies that provided for uncertainty in decision making indicated approximately 26 % remained undecided about vaccinating their children [3]. Logistical or structural barriers caused by inaccessible or inconvenient vaccination delivery can exacerbate parental uncertainties, and also prevent parents with positive vaccination attitudes from acting on their intentions [4].
Health Canada approved the first COVID-19 vaccine product for use among 5–11 year old children in Canada on November 19, 2021 [5]. As of January 01, 2023, approximately 53 % of Canadian children aged 5–11 had received at least one dose [6]. Although COVID-19 vaccine coverage surveillance estimates are available from various government sources, there is little published research exploring uptake patterns among children aged 5–11 years, including variability in coverage across the age spectrum. Measuring age-specific COVID-19 vaccine coverage, and determining associated factors, are necessary to ensure vaccination programs are effectively tailored to population needs, and can provide insight for future vaccination campaigns. Thus, we sought to: 1) estimate coverage by age in years for COVID-19 vaccine among children aged 5–11 years in Alberta, 2) assess vaccine coverage over time since vaccine availability, and 3) investigate factors associated with vaccination.
2. Methods
We conducted a retrospective cohort study of COVID-19 vaccine coverage and correlated factors using linked administrative health data in Alberta, Canada. Vaccination status was assessed between the start of the COVID-19 vaccine program for 5–11 year olds (November 26, 2021) and the end of the study period (December 31, 2022).
2.1. Setting
Alberta has a population of approximately 4.4 million, and is divided into five geographic health zones. In Alberta, routine childhood vaccines are provided by nurses working in public health centres. For the COVID-19 vaccine, doses were offered mainly through public health centres, and augmented by a small number of pharmacies and community physician offices in areas where public health centres were not nearby [7], in order to facilitate timely COVID-19 access. Although some vaccination requirements were put in place for children 12–17 years in some Canadian jurisdictions (e.g. some youth extracurricular activities required vaccination) [8], no such restrictions were placed on younger children [9].
2.2. Cohort and data sources
More than 99 % of Albertans are registered with the province's universal healthcare insurance program. Once registered, each individual is provided a personal healthcare number, which acts as a unique lifetime identifier. Using this identifier, we deterministically linked administrative databases available through the Alberta Ministry of Health. Through the school registration database (Provincial Student Immunization Repository [PSIR]), we identified all children enrolled in Alberta schools during the 2021/2022 school year, as well as individual birth date, sex, and postal code of residence. Children were included in the cohort if they were eligible for vaccination when vaccines became available to this age group on November 26, 2021 (i.e. date of birth between January 01, 2010 and November 26, 2016, aged 5–11 years; children born in 2009 were already eligible for vaccination as a 12 year old [10]). We used a Postal Code Conversion File to link postal codes to Statistics Canada's 2016 census information, to determine place of residence (by population density) and neighborhood income quintile. Individual vaccination status was retrieved from the provincial Immunization and Adverse Reaction to Immunization (Imm/ARI) repository, which includes all COVID-19 vaccine doses administered, regardless of provider. Children who left the province (i.e. cancelled provincial healthcare) or died between September 01, 2021 (the start of the school year) and December 31, 2022 (end of study period) were excluded from the analysis. We excluded children with a residential postal code from outside Alberta, or in the city of Lloydminster (where vaccinations are provided by the neighboring province). Children with a two-dose interval less than the minimum recommendation of 21 days [10] were excluded, as either dose may have represented a data entry error. Finally, those who received a COVID-19 vaccine dose before the vaccine was available in Alberta (November 26, 2021) were excluded, as doses may represent a data entry error, and to ensure uniform follow-up time for all children to calculate cumulative coverage (Supplementary Fig. 1).
2.3. Measures and analysis
To identify vaccine uptake trends over time, we calculated cumulative one- and two-dose vaccine coverage overall, and by age, for the study period. To calculate cumulative coverage, we divided the daily number of children who received a first or second vaccine dose by the total population of children. We calculated the absolute difference in cumulative coverage between two time points to measure increase in coverage. Vaccine delivery location was categorized into public health centres, pharmacies, physician clinics, and others.
We calculated frequencies and percentages for no dose, one dose, and two doses of COVID-19 vaccine received by end of study period for six exposure variables of interest: age as of November 26, 2021; sex; place of residence by population density (metro, moderate metro, urban, moderate urban, rural centre, rural, and rural remote [11]); geographic health zone (South, Calgary, Central, Edmonton, and North); neighborhood income quintile; school authority type (Public, Publicly-funded Catholic, Private, Charter, Francophone, and early childhood services [ECS] private operator [education programs for children under the age of 6]). Children who are homeschooled are registered with the relevant school authority in Alberta; thus, are included in these groups [12]. A sub-group analysis was conducted among children aged 11 years at the start of the study period, comparing the vaccinated proportion of those who turned 12 during the study period to those who remained 11.
Using a modified Poisson regression analysis, we determined the adjusted risk ratio (ARR) and 95 % confidence interval (CI) for the relationship between each exposure variable of interest (age, sex, place of residence, health zone, neighborhood income quintile, and school authority type) and our outcome variable of vaccination status, comparing those who received one or more doses of vaccine during the study period with those who received none. Missing data were assumed to be missing completely at random, thus all the cases with data, including observations with missing values on some variables, were included in the analysis. Data analysis was completed using SAS version 9.4. Ethics approval for this work was obtained from the University of Alberta's Health Research Ethics Board.
3. Results
A total of 377,103 children were included in our cohort. Demographic characteristics of the cohort are provided in Table 1.
Table 1.
Cohort characteristics (N = 377,103).
| Characteristic | n | % |
|---|---|---|
| Age (years)a | ||
| 5 | 50,867 | 13.5 |
| 6 | 54,994 | 14.6 |
| 7 | 55,712 | 14.8 |
| 8 | 54,652 | 14.5 |
| 9 | 55,407 | 14.7 |
| 10 | 55,200 | 14.6 |
| 11 | 50,271 | 13.3 |
| Sex | ||
| Female | 183,675 | 48.7 |
| Male | 193,257 | 51.3 |
| Missing | 171 | 0.1 |
| Neighborhood income quintileb | ||
| Q1 (lowest income) | 60,582 | 16.1 |
| Q2 | 66,012 | 17.5 |
| Q3 | 68,310 | 18.1 |
| Q4 | 86,604 | 23.0 |
| Q5 (highest income) | 95,595 | 25.4 |
| Place of residenceb | ||
| Metro | 197,807 | 52.5 |
| Moderate metro influence | 59,890 | 15.9 |
| Urban | 35,556 | 9.4 |
| Moderate urban influence | 11,360 | 3.0 |
| Rural centre area | 12,846 | 3.4 |
| Rural | 51,545 | 13.7 |
| Rural remote | 8099 | 2.2 |
| Geographic health zone | ||
| Calgary | 144,179 | 38.2 |
| Edmonton | 123,963 | 32.9 |
| South | 27,563 | 7.3 |
| Central | 38,277 | 10.2 |
| North | 43,121 | 11.4 |
| School authority type | ||
| Public | 252,320 | 67.2 |
| Publicly-funded Catholic | 88,289 | 23.5 |
| Private School | 21,984 | 5.9 |
| Charter | 5756 | 1.5 |
| Francophone | 5537 | 1.5 |
| ECS Private Operator | 1576 | 0.4 |
| Missing | 1641 | 0.4 |
ECS, early childhood services.
Age at start of study period (Nov 26, 2021).
Based on Statistics Canada 2016 Census.
3.1. Vaccine coverage
A total of 44.8 % (n = 168,761) of the cohort had received at least one dose during the first 13 months of vaccine availability (9.7 % received only one dose, while 35.1 % received 2 doses) (Fig. 1, Supplementary Table 1). First dose vaccine coverage reached 30 % within the first month of vaccine availability (by December 26, 2021) and increased another 9.1 % in the second month (by January 26, 2022). During the third month of availability, first dose coverage increased by 3 %, reaching 42.1 % on February 26, 2022. For the remaining ten months of follow-up, first dose vaccine coverage increased by less than one percent per month. Among those who received two doses, the median interval between dose 1 and dose 2 was 62 days (range: 21–397 days; Supplementary Table 1, Table 1). The majority of vaccine doses were distributed by public health centres (94.4 %), with only 4.2 % distributed by pharmacies, and remaining doses (1.4 %) distributed from other sources (including First Nations clinics and physician clinics).
Fig. 1.
Cumulative percent of children who have received one and two doses of COVID-19 vaccine.
We observed a similar pattern of increasing coverage with time across the specific age groups, but with a stepwise increase in vaccine coverage with increasing age (Fig. 2). Within two months of vaccine availability, first dose coverage had reached more than 87 % of end-of-study coverage for all age groups except the oldest (11 years of age at the start of the study period) (Fig. 2, Supplementary Table 2). Coverage in the oldest age group increased at a faster rate throughout the remainder of the study period, though the increase was less than 4 % during the third month of vaccine availability (between January 26 and February 26), and less than 1 % in subsequent months for all age groups. Sub-group analysis among children aged 11 years at the start of the study revealed receipt of one or more doses of vaccine was significantly higher among those who turned 12 during our study period, compared to those who remained 11 (56.9 % vs 51.5 %, p < 0.0001; Supplementary Table 3). Receipt of two doses was also significantly higher among those who turned 12 during our study period, compared to those who remained 11 (45.5 % vs 41.2 %, p < 0.0001).
Fig. 2.
Cumulative coverage of COVID-19 vaccine by age category: a) one dose b) two doses. Recommended interval between first and second dose was 8 weeks.
3.2. Factors associated with vaccination
No dose, one dose, and two dose coverage by study characteristics are presented in Table 2. In the multivariable analysis, factors positively associated with receiving at least one dose of COVID-19 vaccination were older age (e.g. 11 years vs 5 years ARR 1.40 [1.38–1.42]; 10 years vs 5 years ARR 1.25 [1.23–1.26]); and living in a higher income neighborhood (e.g. highest quintile vs lowest quintile [ARR 1.77 [1.75–1.79]) (Table 3). By contrast, living in a moderate urban region (ARR 0.61 [0.59–0.64]), rural (ARR 0.62 [0.61–0.64]) or rural remote areas (ARR 0.68 [0.65–0.72]) were associated with lower vaccination compared to living in a metro areas. Similarly, living in the South (ARR 0.88 [0.85–0.91], Central (ARR 0.71 [0.69–0.73]), and North health zones (ARR 0.60 [0.58–0.62]) were associated with lower vaccination, compared to the Calgary zone. In comparison to those attending Public schools, children attending a Charter (ARR 1.18 [1.16–1.21]), or publicly-funded Catholic school (ARR 1.03 [1.03–1.04]) were more likely to be vaccinated, while those attending Francophone (ARR 0.95 [0.92–0.98]), Private (ARR 0.66 [0.64–0.67]), and ECS private Operators (ARR 0.87 [0.82–0.93]) were less likely to be vaccinated. No appreciable differences in coverage were observed by sex.
Table 2.
Proportion of children who received no doses, one dose, or two doses of COVID-19 vaccine during study period by selected background characteristics.
| Variables | No doses |
One dose |
Two doses |
|||
|---|---|---|---|---|---|---|
| n | % (95%CI) | n | % (95%CI) | n | % (95%CI) | |
| Age (years) | ||||||
| 5 | 30,869 | 60.7 (60.3–61.1) | 4645 | 9.1 (8.9–9.4) | 15,353 | 30.2 (29.8–30.6) |
| 6 | 33,097 | 60.2 (59.8–60.6) | 5064 | 9.2 (9.0–9.5) | 16,883 | 30.6 (30.2–31.0) |
| 7 | 32,465 | 58.3 (57.9–58.7) | 5156 | 9.3 (9.0–9.5) | 18,091 | 32.5 (32.1–32.9) |
| 8 | 30,670 | 56.1 (55.7–56.5) | 5142 | 9.4 (9.2–9.7) | 18,840 | 34.5 (34.1–34.9) |
| 9 | 29,773 | 53.7 (53.3–54.2) | 5386 | 9.7 (9.5–10.0) | 20,248 | 36.5 (36.1–37.0) |
| 10 | 28,530 | 51.7 (51.3–52.1) | 5604 | 10.2 (10.0-10.4) | 21,066 | 38.2 (37.8–38.6) |
| 11 | 22,938 | 45.6 (45.2–46.1) | 5479 | 10.9 (10.6–11.2) | 21,854 | 43.5 (43.0–43.9) |
| Sex | ||||||
| Female | 101,056 | 55.02 (54.8–55.3) | 17,586 | 9.6 (9.4–9.7) | 65,033 | 35.4 (35.2–35.6) |
| Male | 107,219 | 55.5 (55.3–55.7) | 18,870 | 9.8 (9.6–9.9) | 67,168 | 34.8 (34.5–35.0) |
| Neighborhood income quintile | ||||||
| Q1 (lowest income) | 41,010 | 67.7 (67.3–68.1) | 5854 | 9.7 (9.4–9.9) | 13,718 | 22.6 (22.3–23.0) |
| Q2 | 40,769 | 61.8 (61.4–62.1) | 6403 | 9.7 (9.5–9.9) | 18,840 | 28.5 (28.2–28.9) |
| Q3 | 37,431 | 54.8 (54.4–55.2) | 6889 | 10.1 (9.9–10.3) | 23,990 | 35.1 (34.8–35.5) |
| Q4 | 45,245 | 52.2 (51.9–52.6) | 8239 | 9.5 (9.3–9.7) | 33,120 | 38.2 (37.9–38.6) |
| Q5 (highest income) | 43,887 | 45.9 (45.6–46.2) | 9091 | 9.5 (9.3–9.7) | 42,617 | 44.6 (44.2–44.9) |
| Place of residence | ||||||
| Metro | 92,282 | 46.7 (46.4–46.9) | 20,598 | 10.4 (10.3–10.6) | 84,927 | 42.9 (42.7–43.2) |
| Metro Influence | 31,480 | 52.6 (52.2–53.0) | 6046 | 10.1 (9.9-10.3) | 22,364 | 37.3 (36.9–37.7) |
| Urban | 22,381 | 63.0 (62.4–63.5) | 3552 | 10.0 (9.7–10.3) | 9623 | 27.1 (26.7–27.5) |
| Moderate urban | 8616 | 75.9 (75.1–76.6) | 781 | 6.9 (6.4-7.3) | 1963 | 17.3 (16.6–18.0) |
| Rural centre area | 8572 | 66.7 (65.9–67.5) | 1122 | 8.7 (8.3–9.2) | 3152 | 24.5 (23.8–25.3) |
| Rural | 38,785 | 75.2 (74.9–75.6) | 3751 | 7.3 (7.1–7.5) | 9009 | 17.5 (17.2–17.8) |
| Rural remote | 6226 | 76.9 (76.0–77.8) | 626 | 7.7 (7.2–8.3) | 1247 | 15.4 (14.6–16.2) |
| Geographic health zone | ||||||
| Calgary | 68,353 | 47.4 (47.2–47.7) | 15,188 | 10.5 (10.4–10.7) | 60,683 | 42.1 (41.8–42.3) |
| Edmonton | 27,827 | 72.7 (72.3–73.1) | 3074 | 8.0 (7.8–8.3) | 7376 | 19.3 (18.9–19.7) |
| South | 61,953 | 50.0 (49.7–50.3) | 12,360 | 10.0 (9.8–10.1) | 49,650 | 40.0 (39.8–40.3) |
| Central | 18,549 | 67.3 (66.7–67.9) | 2401 | 8.7 (8.4–9.0) | 6613 | 24.0 (23.5–24.5) |
| North | 31,660 | 73.4 (73.0–73.8) | 3453 | 8.0 (7.8–8.3) | 8008 | 18.6 (18.2–18.9) |
| School authority type | ||||||
| Public | 140,158 | 55.6 (55.4–55.7) | 24,991 | 9.9 (9.8–10.0) | 87,171 | 34.6 (34.4–34.8) |
| Publicly-funded Catholic | 45,617 | 51.7 (51.3–52.0) | 8842 | 10.0 (9.8–10.2) | 33,830 | 38.3 (38.0–38.6) |
| Private School | 15,525 | 70.6 (70.0–71.2) | 1313 | 6.0 (5.7–6.3) | 5146 | 23.4 (22.9–24.0) |
| Charter | 2089 | 36.3 (35.1–37.5) | 642 | 11.2 (10.3–12.0) | 3025 | 52.6 (51.3–53.4) |
| Francophone | 3105 | 56.1 (54.8–57.4) | 412 | 7.4 (6.8-8.1) | 2020 | 36.5 (35.2–37.8) |
| ECS Private Operator | 981 | 62.3 (59.9–64.6) | 148 | 9.4 (7.8–10.1) | 447 | 28.4 (26.1–30.6) |
CI, confidence interval; ECS, early childhood services.
Table 3.
Proportion of children who received at least one dose of COVID-19 vaccine, with unadjusted and adjusted risk ratios for factors associated with vaccination status.
| Characteristic | Coverage ( ≥ 1 dose), % (n) | Unadjusted risk ratio (95 % CI) | Adjusted risk ratio (95 % CI) | p-value |
|---|---|---|---|---|
| Age (years) | ||||
| 5 | 39.3 (19,998) | Ref | Ref | |
| 6 | 39.8 (21,897) | 1.01 (1.00-1.03) | 1.03 (1.01-1.04) | 0.0004 |
| 7 | 41.7 (23,247) | 1.06 (1.05-1.08) | 1.08 (1.06-1.09) | <.0001 |
| 8 | 43.9 (23,982) | 1.12 (1.10-1.13) | 1.13 (1.12-1.15) | <.0001 |
| 9 | 46.3 (25,634) | 1.18 (1.16-1.19) | 1.19 (1.18-1.21) | <.0001 |
| 10 | 48.3 (26,670) | 1.23 (1.21-1.25) | 1.25 (1.23-1.26) | <.0001 |
| 11 | 54.4 (27,333) | 1.38 (1.36-1.40) | 1.40 (1.38-1.42) | <.0001 |
| Sex | ||||
| Male | 45.0 (82,619) | Ref | Ref | |
| Female | 44.5 (86,038) | 1.01 (1.00-1.02) | 1.01 (1.00-1.02) | 0.0078 |
| Neighborhood income quintile | ||||
| Q1 (lowest income) | 32.3 (19,572) | Ref | Ref | |
| Q2 | 38.2 (25,243) | 1.18 (1.17-1.20) | 1.23 (1.21-1.25) | <.0001 |
| Q3 | 45.2 (30,879) | 1.40 (1.38-1.42) | 1.43 (1.41-1.45) | <.0001 |
| Q4 | 47.8 (41,359) | 1.48 (1.46-1.50) | 1.55 (1.53-1.57) | <.0001 |
| Q5 (highest income) | 54.1 (51,708) | 1.67 (1.65-1.70) | 1.77 (1.75-1.79) | <.0001 |
| Place of residence | ||||
| Metro | 53.4 (105,525) | Ref | Ref | |
| Moderate metro influence | 47.4 (28,410) | 0.89 (0.88-0.90) | 0.80 (0.80-0.82) | <.0001 |
| Urban | 37.1 (13,175) | 0.69 (0.68-0.70) | 0.91 (0.88-0.94) | <.0001 |
| Moderate urban influence | 24.2 (2744) | 0.45 (0.44-0.47) | 0.61 (0.59-0.64) | <.0001 |
| Rural centre area | 33.3 (4274) | 0.62 (0.61-0.64) | 0.75 (0.72-0.77) | <.0001 |
| Rural | 24.8 (12,760) | 0.46 (0.46-0.47) | 0.62 (0.61-0.64) | <.0001 |
| Rural Remote | 23.1 (1873) | 0.43 (0.42-0.45) | 0.68 (0.65-0.72) | <.0001 |
| Geographic health zone | ||||
| Calgary | 52.6 (75,826) | Ref | Ref | |
| Edmonton | 50.0 (62,010) | 0.95 (0.94-0.96) | 0.95 (0.94-0.95) | <.0001 |
| South | 32.7 (9014) | 0.62 (0.61-0.63) | 0.88 (0.85-0.91) | <.0001 |
| Central | 27.3 (10,450) | 0.52 (0.51-0.53) | 0.71 (0.69-0.73) | <.0001 |
| North | 26.6 (11,461) | 0.50 (0.50-0.51) | 0.60 (0.58-0.62) | <.0001 |
| School authority type | ||||
| Public | 44.5 (112,162) | Ref | Ref | |
| Publicly-funded Catholic | 48.3 (42,672) | 1.09 (1.08-1.10) | 1.03 (1.03-1.04) | <.0001 |
| Private | 29.4 (6459) | 0.66 (0.65-0.67) | 0.66 (0.64-0.67) | <.0001 |
| Charter | 63.7 (3667) | 1.43 (1.40-1.46) | 1.18 (1.16-1.20) | <.0001 |
| Francophone | 43.4 (2432) | 0.99 (0.96-1.02) | 0.95 (0.92-0.98) | 0.0005 |
| ECS Private Operator | 37.8 (595) | 0.85 (0.80-0.91) | 0.87 (0.82-0.93) | <.0001 |
CI, confidence interval; ECS, early childhood services.
4. Discussion
We used school enrollment records and a population-based immunization repository to determine COVID-19 vaccine coverage among children aged 5–11 years during the first thirteen months of vaccine availability in Alberta, Canada, from November 26, 2021 through December 31, 2022. Our results indicate that less than half had received a dose of COVID-19 vaccine by the end of our study period (December 31, 2022), and most had received their initial dose within the first two months of vaccine availability (by January 26, 2022). Similar patterns in vaccine uptake have been noted in other Canadian provinces [6], and other countries [13], despite different levels of coverage. Our coverage level was lower than previously reported parental intentions for similar age groups in Canada (56 % intended, 33 % undecided for children 5–11 years [14]) and Alberta (60 % intended, 31 % undecided for children aged 9–12 years [15]). This suggests that a significant portion of parents with unvaccinated children may still be open to COVID-19 vaccination, but may have experienced logistical or structural barriers to acting on those intentions. Conversely, survey results may have overestimated vaccination intentions, or intentions may have changed over time.
Notably, coverage among 5–11 year olds in Alberta is lower than other Canadian provinces and territories, which are estimated to range from 50.1 to 88.8 % (as of January 01, 2023 [6]). This discrepancy is not apparent for other childhood vaccines [16], indicating that regional efforts that have been used to promote COVID-19 vaccine uptake should be explored. For example, school-based delivery of COVID-19 vaccines has been used in Quebec, Saskatchewan, and British Columbia [14]. School-based programs have been used effectively in Canada to achieve high and equitable coverage for other childhood vaccines [17,18]; in fact, simply encouraging vaccination in school may promote uptake among this age group [19]. Our results also indicate that prioritizing vaccination interventions by school type may be useful for targeting areas of low coverage. However, lower vaccine coverage among those attending private schools has been consistently reported for other routine vaccines [20,21], and, while Canadian parents who support COVID-19 vaccination for their children are largely in favor of school-based delivery, those who are undecided may be less supportive [14]. The province of Alberta did expand delivery options in March 2022, increasing availability through pharmacies and primary care physician offices, and offering walk-in appointments and extended hours at select public health centres [22,23]. These efforts did not appear to impact provincial-level vaccine coverage; however, as interventions were applied only in specific areas, there may have been significant localized impacts. In addition, these efforts may have been more effective if implemented earlier in the vaccine roll-out, when parent interest was high. More information about the challenges and successes of regional programs, school-based and otherwise, is required.
Nearly 10 % of children who received an initial dose of COVID-19 vaccine did not receive a second dose within the study timeframe. These children reflect a missed opportunity to increase vaccine series completion, which is crucial to ensure protection is maximized. Reminders for upcoming vaccination doses, and recalls for overdue vaccinations, have been identified as effective strategies for increasing routine vaccination rates among children [24]; implementation of this approach may be both particularly useful and difficult for COVID-19 vaccines and future pandemic vaccines, due to frequently changing guidelines. Tailoring these interventions to the local population may be particularly effective [25]. Additionally, techniques to alleviate first dose pain and anxiety may promote second dose vaccine compliance, particularly in this age group [26]. Given the variable rate in follow-up time after first dose receipt, we did not explore factors associated with delaying or not receiving a second dose. Future research should recognize this group as a unique population, and determine factors associated with incomplete and/or delayed vaccination.
In our study, younger ages within the 5–11 year old range were significantly associated with lower vaccine coverage. This pattern persisted throughout the age range, with higher coverage even noted among children who turned 12 years during the study time period compared to those who remained 11. However, coverage among those who turned 12 was still below coverage for the 12–17 year old age group in Alberta (82 % [6]), indicating that the relationship between age and uptake may extend to older children. Previous survey results indicate mixed results on the impact of child age on parental vaccination intention [3]; however, studied age ranges varied. Our findings are consistent with a Canadian survey that reported parents of 8–11 year olds were more likely to report positive vaccination intentions than those of 5–7 year olds (58.1 % vs 54.8 %) [14]. Murthy et al. [27] found a similar relationship between age and coverage during the first two months of vaccine availability in the US; our results indicate that this pattern persists. Therefore, treating 5-11-year-olds as one homogeneous group for messaging and vaccine delivery may not be appropriate for optimizing vaccine coverage for COVID-19 and other vaccines. Instead, age-specific information on vaccine safety and effectiveness should be provided, including greater efforts to publicize the growing number of children worldwide who have been safely vaccinated. This may be particularly important for the large portion of parents who have stated they wish to “wait and see” [3,28,29].
We found that vaccine coverage increased with both income and population density and varied by geographic health zone. These relationships are consistent with patterns noted for adult COVID-19 vaccine intention and uptake [30,31], which is not surprising given that parental vaccination status is highly predictive of vaccination intention for their children [32]. However, the vaccination rate for children in this age group is much lower than that reported for adults (greater than 85 % [6]). This disparity has also been noted for childhood vaccination intentions among parents [14,32], with lower intentions associated with perceptions of lower risk of severe COVID-19 disease in children [3] and greater concern over unknown or potential side effects related to vaccination [29]. This means that trusted healthcare providers must have the information and training required to have effective conversations in their communities [33]. Efforts to promote COVID-19 vaccination for children 5–11 as a social norm by leveraging informal social connections may also be effective [28,34].
4.1. Strengths and limitations
This study benefited from timely population-based data, using individual-level school enrollment and immunization records. By using school enrollment records to identify our cohort, we were able to accurately identify children who are current residents of Alberta. In addition, our overall coverage estimates were similar to those posted by the Alberta Ministry of Health, who apply population weights to measure coverage. For those children who were vaccinated, we used age at start of study period as an estimate for age at vaccination; thus, the positive association between increasing age and vaccine coverage may be underestimated. Although all vaccine-eligible 5 year olds were also eligible for school enrollment [35], this age group may have been underrepresented in this study as kindergarten enrollment is not mandatory in Alberta [36]. Some of the children recorded as having only received 1 vaccine dose may not have been yet eligible for a second vaccine dose during our study period; however, this represents less than 0.1 % of vaccinated children in the study.
5. Conclusions
Our results indicate that parents either sought vaccination for their 5-11-year-old children soon after it was available or not at all. Thus, having a well-developed vaccine roll-out plan promptly after vaccine availability may result in higher coverage, and innovative messaging and delivery options will be required to increase uptake in this age group over the longer term. Although this uptake pattern is consistently noted across Canadian provinces, lower coverage levels in Alberta indicate that understanding regional differences in COVID-19 vaccination efforts is required. We found that specific child age was significantly related to vaccine coverage, even after correcting for sociodemographic and regional variability, suggesting that the 5–11-year-old age group should not be treated as one homogeneous group. Rather, tailored messaging to parents of younger children within this age group should be used. We also found some indication that efforts to promote timeliness of two-dose series completion are required. These important lessons should be used to guide ongoing COVID-19 vaccine programming for children, as well as introduction of new vaccines in the future.
Ethical approval
Ethics approval for this work was obtained from the University of Alberta's Health Research Ethics Board.
Funding
All phases of this study were supported by an Alberta Health grant, #007720. The funding source had no role in study design analysis and interpretation of data, the writing of the report, and the decision to submit the paper for publication.
Data sharing statement
No data are available. The steward of the data used in this study is the Alberta Ministry of Health, who maintains the data for the purpose of health system administration. Thus, the authors are not at liberty to make the data publicly available.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We acknowledge the support of Crystal Du in preparation of the manuscript.
Footnotes
Supplementary data to this article can be found online at https://doi.org/10.1016/j.puhip.2024.100467.
Appendix A. Supplementary data
The following is the supplementary data to this article.
References
- 1.Dubé E., Laberge C., Guay M., Bramadat P., Roy R., Bettinger J.A. Vaccine hesitancy: an overview. Hum. Vaccines Immunother. 2013;9(8):1763–1773. doi: 10.4161/hv.24657. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Enkel S.L., Attwell K., Snelling T.L., Christian H.E. ‘Hesitant compliers’: qualitative analysis of concerned fully-vaccinating parents. Vaccine. 2018;36(44):6459–6463. doi: 10.1016/j.vaccine.2017.09.088. [DOI] [PubMed] [Google Scholar]
- 3.Galanis P., Vraka I., Siskou O., Konstantakopoulou O., Katsiroumpa A., Kaitelidou D. Willingness, refusal and influential factors of parents to vaccinate their children against the COVID-19: a systematic review and meta-analysis. Prev. Med. 2022;157 doi: 10.1016/j.ypmed.2022.106994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Brewer N.T., Chapman G.B., Rothman A.J., Leask J., Kempe A. Increasing vaccination: putting psychological science into action. Psychol. Sci. Publ. Interest. 2017;18(3):149–207. doi: 10.1177/1529100618760521. [DOI] [PubMed] [Google Scholar]
- 5.Health Canada Health Canada authorizes use of Comirnaty (the Pfizer-BioNTech COVID-19 vaccine) in children 5 to 11 years of age. 2021. https://www.canada.ca/en/health-canada/news/2021/11/health-canada-authorizes-use-of-comirnaty-the-pfizer-biontech-covid-19-vaccine-in-children-5-to-11-years-of-age.html Published November 19.
- 6.Public Health Agency of Canada COVID-19 vaccination coverage in Canada. 2022. https://health-infobase.canada.ca/covid-19/vaccination-coverage/ Published July 17.
- 7.Government of Alberta Pfizer pediatric vaccine rollout to begin | Lancement du déploiement du vaccin pédiatrique de Pfizer. 2021. https://www.alberta.ca/news.aspx Published November 23.
- 8.CTV News Edmonton “Erring on the side of caution”: Edmonton adopts proof-of-vaccine program for youth sports at its facilities. Edmonton. 2021. https://edmonton.ctvnews.ca/erring-on-the-side-of-caution-edmonton-adopts-proof-of-vaccine-program-for-youth-sports-at-its-facilities-1.5596392 Published September 22.
- 9.Government of Alberta Children aged 5-11 now eligible for COVID-19 vaccine. 2021. https://www.alberta.ca/news.aspx Published November 19.
- 10.Alberta Health Services G. 2022. COVID-19 Vaccine - MRNA Pfizer BioNTech (Comirnaty) - Ultra Frozen Vaccine Adult Formulation 12 Years of Age and Older Biological Page.https://www.albertahealthservices.ca/assets/info/hp/cdc/if-hp-cdc-ipsm-covid-19-pfizer-bio-pg-07-203.pdf [Google Scholar]
- 11.Alberta Health Services and Alberta Health . Canada.; Alberta: 2018. Official Standard Geographic Areas. [Google Scholar]
- 12.Government of Alberta. Student population statistics. Accessed August 4, 2022. https://www.alberta.ca/student-population-statistics.aspx.
- 13.American Academy of Pediatrics Children and COVID-19 vaccinations trends. 2022. https://www.aap.org/en/pages/2019-novel-coronavirus-covid-19-infections/children-and-covid-19-vaccination-trends/
- 14.Humble R.M., Sell H., Wilson S., et al. Parents' perceptions on COVID-19 vaccination as the new routine for their children ≤ 11 years old. Prev. Med. 2022;161 doi: 10.1016/j.ypmed.2022.107125. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Hetherington E., Edwards S.A., MacDonald S.E., et al. SARS-CoV-2 vaccination intentions among mothers of children aged 9 to 12 years: a survey of the All Our Families cohort. CMAJ Open. 2021;9(2):E548–E555. doi: 10.9778/cmajo.20200302. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Public Health Agency of Canada Vaccine coverage in Canadian children: results from the 2017 childhood national immunization coverage survey (cNICS) 2020. https://www.canada.ca/en/public-health/services/publications/healthy-living/2017-vaccine-uptake-canadian-children-survey.html Published January 29.
- 17.Dubé E., Gagnon D., Clément P., et al. Challenges and opportunities of school-based HPV vaccination in Canada. Hum. Vaccines Immunother. 2019;15(7–8):1650–1655. doi: 10.1080/21645515.2018.1564440. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Musto R., Siever J.E., Johnston J.C., Seidel J., Rose S., Mcneil D.A. 2013. Social equity in human papillomavirus eaccination: a natural experiment in Calgary Canada.http://www.biomedcentral.com/1471-2458/13/640 Published online. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.KFF COVID-19 vaccine monitor dashboard. KFF. 2022. https://www.kff.org/coronavirus-covid-19/dashboard/kff-covid-19-vaccine-monitor-dashboard/ Published July 26.
- 20.Carpiano R.M., Bettinger J.A. Vaccine coverage for kindergarteners: factors associated with school and area variation in Vancouver, British Columbia. Vaccine Rep. 2016;6:50–55. doi: 10.1016/j.vacrep.2016.10.001. [DOI] [Google Scholar]
- 21.Sell H., Paudel Y.R., Voaklander D., MacDonald S.E. School immunization coverage during the COVID-19 pandemic. A retrospective cohort study. 2022 doi: 10.1101/2022.05.04.22274665. Published online May 7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Alberta Blue Cross COVID-19 immunization program | Alberta blue cross. 2022. https://www.ab.bluecross.ca/news/covid-19-immunization-program-information.php Published.
- 23.Government of Alberta Making pediatric COVID-19 vaccines more accessible. https://www.alberta.ca/news.aspx Published February 23 2022.
- 24.Jacobson Vann J.C., Jacobson R.M., Coyne-Beasley T., Asafu-Adjei J.K., Szilagyi P.G. Patient reminder and recall interventions to improve immunization rates. Cochrane Effective Practice and Organisation of Care Group. Cochrane Database Syst. Rev. 2018;2018(1) doi: 10.1002/14651858.CD003941.pub3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Jong K.M., Sikora C.A., MacDonald S.E. Childhood immunization appointment reminders and recalls: strengths, weaknesses and opportunities to increase vaccine coverage. Publ. Health. 2021;194:170–175. doi: 10.1016/j.puhe.2021.02.034. [DOI] [PubMed] [Google Scholar]
- 26.Taddio A., Ilersich A., McMurtry C.M., Bucci L.M., MacDonald N.E. Managing pain and fear: playing your CARDs to improve the vaccination experience. Can. Comm. Dis. Rep. 2021;47(1):87–91. doi: 10.14745/ccdr.v47i01a12. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Murthy N.C., Zell E., Fast H.E., et al. Disparities in first dose COVID-19 vaccination coverage among children 5–11 years of age, United States. Emerg. Infect. Dis. 2022;28(5):986–989. doi: 10.3201/eid2805.220166. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Head K.J., Zimet G.D., Yiannoutsos C.T., Silverman R.D., Sanner L., Menachemi N. Factors that differentiate COVID-19 vaccine intentions among Indiana parents: implications for targeted vaccine promotion. Prev. Med. 2022;158 doi: 10.1016/j.ypmed.2022.107023. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Williams S.N. ‘I don't want my son to be part of a giant experiment’: public attitudes towards COVID-19 vaccines in children. Publ. Health. 2022;205:116–121. doi: 10.1016/j.puhe.2022.01.016. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.MacDonald S.E., Paudel Y.R., Du C. COVID-19 vaccine coverage among immigrants and refugees in Alberta: a population-based cross-sectional study. Glob Health. 2022;12:05053. doi: 10.7189/jogh.12.05053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Public Health Agency of Canada . 2020. COVID-19 Summary of Vaccine Knowledge, Attitudes, and Behaviors; p. 81. [Google Scholar]
- 32.Szilagyi P.G., Shah M.D., Delgado J.R., et al. Parents' intentions and perceptions about COVID-19 vaccination for their children: results from a national survey. Pediatrics. 2021;148(4) doi: 10.1542/peds.2021-052335. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Frew P.M., Lutz C.S. Interventions to increase pediatric vaccine uptake: an overview of recent findings. Hum. Vaccines Immunother. 2017;13(11):2503–2511. doi: 10.1080/21645515.2017.1367069. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Konstantinou P., Georgiou K., Kumar N., et al. Transmission of vaccination attitudes and uptake based on social contagion theory: a scoping review. Vaccines. 2021;9(6):607. doi: 10.3390/vaccines9060607. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Government of Alberta Early childhood education. https://www.alberta.ca/early-childhood-education.aspx
- 36.Government of Alberta. Education Act. Published September 17, 2012. Accessed May 2, 2023. https://kings-printer.alberta.ca/1266.cfm?page=E00P3.cfm&leg_type=Acts&isbncln=9780779829408&display=html.
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.