key: cord-0770267-y37b9f4l
authors: Lavoie, K. L.; Gosselin Boucher, V.; Stojanovic, J.; Gupta, S.; Gagne, M.; Joyal-Desmarais, K.; Seguin, K.; Sheinfield-Gorin, S.; Ribeiro, P. A. B.; Voisard, B.; Vallis, M.; Corace, K.; Presseau, J.; Bacon, S. L.
title: Understanding national trends in COVID-19 vaccine hesitancy in Canada - April 2020 to March 2021
date: 2021-11-11
journal: nan
DOI: 10.1101/2021.11.10.21266174
sha: d7ce816139d2fc8c541954efa1b1dac0f49bb039
doc_id: 770267
cord_uid: y37b9f4l

Objective: Key to reducing COVID-19 morbidity and mortality and reducing the need for further lockdown measures in Canada and worldwide is widespread acceptance of COVID-19 vaccines. Vaccine hesitancy has emerged as a key barrier to achieving optimal vaccination rates, for which there is little data among Canadians. This study examined rates of vaccine hesitancy and their correlates among Canadian adults. Methods: This study analyzed data from five age, sex and province-weighted population-based samples to describe rates of hesitancy between April 2020 and March 2021 among Canadians who completed online surveys as part of the iCARE Study, and various sociodemographic, clinical and psychological correlates. Vaccine hesitancy was assessed by asking: If a vaccine for COVID-19 were available today, what is the likelihood that you would get vaccinated? Responses were dichotomized into very likely, unlikely, somewhat unlikely (reflecting some degree of vaccine hesitancy) vs extremely likely to get the vaccine, which was the comparator. Results: Overall, 15,019 respondents participated in the study. A total of 42.2% of respondents reported vaccine hesitancy over the course of the study, which was lowest during surveys 1 (April 2020) and 5 (March 2021) and highest during survey 3 (November 2020). Fully adjusted multivariate logistic regression analyses revealed that women, those aged 50 and younger, non-Whites, those with high school education or less, and those with annual household incomes below the poverty line in Canada (i.e., $60,000) were significantly more likely to report being vaccine hesitant over the study period, as were essential and healthcare workers, parents of children under the age of 18, and those who do not get regular flu vaccines. Believing engaging in infection prevention behaviours (like vaccination) is important for reducing virus transmission and high COVID-19 health concerns (being infected and infecting others) were associated with 77% and 54% reduction in vaccine hesitancy, respectively, and having high personal financial concerns (worried about job or income loss) was associated with 1.33 times increased odds of vaccine hesitancy. Conclusion: Results point to the importance of targeting vaccine efforts to women, younger people and socioeconomically disadvantaged groups, and that vaccine messaging should emphasize the benefits of getting vaccinated, and how the benefits (particularly to health) far outweigh the risks. Future research is needed to monitor ongoing changes in vaccine intentions and behaviour, as well as to better understand motivators and facilitators of vaccine acceptance, particularly among vulnerable groups.

The SARS-CoV-2 virus causing coronavirus disease has caused a global pandemic, resulting in significant morbidity, mortality and economic and social disruption in Canada and around the world. Key to reducing disease morbidity and mortality and reducing the need for future lockdowns is widespread acceptance of COVID-19 vaccines, several of which have been approved for those aged 12 and older by Health Canada, 1 with approvals pending for children aged [5] [6] [7] [8] [9] [10] [11] . High rates of vaccine acceptance was thought to be necessary for achieving target levels of herd immunity, 2 but it has proven difficult to estimate the minimum threshold of immunization needed to achieve this due to the emergence of highly virulent strains like [Delta] whose R0 has been estimated to be 5 to 6 times greater than the original Wuhan SARS-CoV-2 strain. 3, 4 This has led experts to recommend vaccinating as much of the population as possible and exploring the need for additional, 'booster', or yearly doses. 5 Regardless of how COVID-19 vaccination schedules unfold over the short and longer-term, the ultimate success of vaccination programs depends on people's willingness to get vaccinated. However, several reports from nations where vaccines have been widely available indicate that intentions to get a COVID-19 vaccine have been steadily declining (and rates of vaccine hesitancy steadily increasing) since the first pandemic wave. For example, a longitudinal study in the US reported significant declines in the likelihood of getting vaccinated (somewhat or very likely to get vaccinated), from a high of 74% in early April 2020 to a low of 56% by early December 2020. 6 These declines were observed for both men and women and in all age, racial/ethnic and education subgroups. Similar trends were also observed in Australia, where 31.9% of Australians reported being less willing to get vaccinated between August 2020 and January 2021, and was particularly prevalent among Indigenous populations and those who did not complete high school. 7 Since then, there have been 175 studies worldwide have been published on vaccine hesitancy through to the end of August 2021, including 21 reporting data from Canada. According to a living systematic review by Crawshaw et al., 8 the interquartile range of vaccine hesitancy was 12-24%, with a mean of 17%. Overall, these results raise important questions about vaccine attitudes and intentions among Canadians, whose willingness to get vaccinated now and in the future will be critical for optimizing the success of Canada's vaccine strategy and our successful transition out of the pandemic.

Key to optimizing vaccination rates is understanding patterns and correlates of hesitancy over time.

This will allow us to improve vaccine policy planning, develop targeted interventions, and enhance tailoring of vaccine messaging to vulnerable groups. To this end, we examined rates of vaccine hesitancy and their correlates among Canadians by analyzing data from five age, sex and province-weighted population-based samples who completed online surveys between April 2020 and March 2021. In order to explore the factors associated with vaccine hesitancy over time, data across all surveys were examined as a function of key sociodemographics, clinical characteristics, and psychological factors known to be important for vaccine behaviour. 9 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

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The International COVID-19 Awareness and Responses Evaluation (iCARE) Study (www.icarestudy.com) 10 is an ongoing, international, multi-wave, cross-sectional observational survey study of public awareness, attitudes, and responses to COVID-19 public health policies. The study is led by researchers from the Montreal Behavioural Medicine Centre (MBMC: www.mbmc-cmcm.ca) in collaboration with a team of over 200 international collaborators from more than 40 countries. The survey was designed with international experts to assess constructs from the Capability, Opportunity, Motivation -Behaviour (COM-B) Model of the Behaviour Change Wheel 11 and from the Health Belief Model. 12, 13 The survey also includes questions on sociodemographics, physical and mental health conditions, general health behaviours, previous COVID-19 infection, awareness of local government prevention policies, perceptions and attitudes about these policies, adherence to prevention behaviours, COVID-19-related concerns and impacts, and vaccine attitudes and intentions (the survey can be found at: www.osf.io/nswcm). The primary REB approval was obtained from the 

For this study, we report data from five nationally representative online surveys of Canadians aged 18 years and over using a recognized polling firm who recruits participants through their proprietary online panel (Leger Opinion). This panel includes over 400,000 Canadians, the majority of which (61%) were recruited within the past 10 years. Two thirds of the panel were recruited randomly by telephone, with the remainder recruited via publicity and social media. Using data from Statistics Canada, results were weighted within each province according to the sex and age of the respondents. Then, the weight of each province was further adjusted to represent their actual weight within the Canadian federation. Data were collected between April 9 th and 20 th , 2020 (Survey 1), June 4 th and 17 th , 2020 (Survey 2), October 29 th and November 11 th , 2020 (Survey 3), January 27 and February 7th (Survey 4), and March 11 th to 29 th (Survey 5), respectively, using a self-administered Computer-Assisted Web Interface .

To assess vaccine hesitancy, we asked: "If a vaccine for COVID-19 were available today, what is the likelihood that you would get vaccinated?" Response options (very unlikely, unlikely, somewhat likely, extremely likely, I don't know/prefer not to answer) were dichotomized into 'very unlikely, unlikely, somewhat . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint likely' to describe those indicating at least some degree of hesitancy, vs. 'very likely' to describe those with very high intentions to get vaccinated. A dichotomous outcome was chosen to identify all those who could benefit from intervention, with those responding 'very likely' to get vaccinated treated as the comparator/reference.

We assessed two psychological factors that are often important motivators of engaging in protective health behaviours: perceived importance of engaging in infection prevention behaviours, and the nature and extent of people's COVID-19-related concerns. [12] [13] [14] To assess the concerns people have about the COVID-19 virus and its impacts, individuals were presented with the following prompt: "Because of COVID-19, I am concerned about…". Respondents then had to indicate the extent which they had 10 specific concerns, choosing among 'not at all', 'very little', 'somewhat', 'to a great extent,' and 'I don't know/prefer not to answer'. To cluster COVID-19-related concerns, we performed a principal component analysis on a polychoric correlation matrix of the 10 variables in the concerns module (ordinal scale, as detailed above), details of which can be found elsewhere. 15 We observed a threecomponent structure that included: 'Health concerns', 'personal financial concerns' and 'social and economy concerns'. Mean values (M) and standard deviations (SD) for each of the three components are reported as a score out of four, from 1= 'not at all' to 4 = 'to a great extent'. Internal consistency for the components ranged from satisfactory (social/economy concerns α=0.69) to excellent (personal financial concerns α=0.82; health concerns α=0.91) for the individual components. 15

Several survey questions included an answer 'I don't know/I prefer not to answer' which was recoded as a missing value and analyses were based on complete case records. Descriptive statistics (weighted means, SDs, and proportions) were calculated to describe the sample in terms of demographic characteristics, across all surveys. Univariate analyses were conducted to examine differences in sociodemographic characteristics (weighted proportions) as a function of vaccine hesitancy across the five time points. Three separate multivariable logistic regression models were performed to assess associations between vaccine hesitancy (dependent variable) and participant sociodemographic (i.e., age, sex, ethnicity, education, employment status, . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 11, 2021. ;  annual household income, parental status, worker status, provincial region) and clinical characteristics (i.e., health risk conditions, history of flu vaccine, previous COVID-19 infection) (independent variables: Model 1), vaccine hesitancy (dependant variable) and perceived importance of prevention behaviours (independent variable: Model 2), and vaccine hesitancy (dependent variable) and the nature and extent of the three types of COVID-19-related concerns (independent variables: Model 3). Analyses were conducted across all surveys combined and models were partially (covariates included age, sex, ethnicity, and survey wave) and fully adjusted (covariates included age, sex, ethnicity, survey wave, education, employment status, annual household income, health risk condition, essential worker, healthcare worker, parental status, history of flu vaccine, COVID-19 test result). All variables were selected a-priori based on pre-exiting data. 9 Analyses were also conducted as a function of time point/survey to examine trends over time, assessed using the Welch test.

All statistical tests were two-sided and a p-value < 0.05 was considered as statistically significant. Statistical analysis was performed in SAS, version 9.4.

Our sample included a total of 15,019 respondents (survey 1, n=3003; survey 2, n=3005; survey 3, n=3005, survey 4 = 3000, and survey 5 = 3006) who completed a survey between April 9 th 2020 and March 29 th 2021, with a response rate of 16% (survey 4) to 25% (survey 5) for each survey (which is considered acceptable for online panels 16 ). Participant characteristics collapsed across all surveys and then as a function of survey round can be found in Table 1 and Supplementary Table S1, respectively. Respondents across all five surveys were 51.6% female (range 18-95 years) with a mean age 48.1 [SD 17.2] years. The majority of the sample were White (80.8%), had a high school or less education (72.3%), and reported total family annual incomes over $60,000 (51.7%). Nearly half (49.7%) reported being currently employed. Just over 44% reported having at least one physician-diagnosed health risk condition (e.g., cardiovascular or lung disease, cancer, diabetes, obesity), and just over a quarter (26%) reported having a physician-diagnosed psychiatric disorder (e.g., depressive or anxiety disorder). About 16% identified as being an essential service worker, just over 4% identified as being a healthcare worker, and 21.5% identified as being parents of children under 18. Approximately 17% of respondents had gotten tested for COVID-19, with nearly 1% reporting testing positive. Only 43% of respondents reported getting a flu vaccine at least 3 times or more over the past five years. In general, compared to census data available through Statistics Canada, participants across all five surveys were well distributed across provincial regions, age groups, employment status and income, and there were equal proportions of men and women. However, those with a graduate or post-graduate degree and people of color were less represented.

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Rates of vaccine hesitancy across time/survey round are presented in Figure 1 . Overall, 42.2% of respondents reported vaccine hesitancy over the course of the study period, though we observed significant variations in vaccine hesitancy rates over time (survey 1: 36.8%, survey 2: 44.6%; survey 3: 52.9%, survey 4: 39.6%, survey 5: 36.9%). As can be seen in Figure 1 , vaccine hesitancy was lowest during surveys 1 (April 2020) and 5 (March 2021), and highest during survey 3 (November 2020).

Participant characteristics presented as a function of vaccine hesitancy status across all surveys/time points are presented in Figure 2 (individual survey data can be found in Supplement Table S2 ). Across all surveys, rates of vaccines hesitancy were significantly higher among younger age groups (< 25 years and 26-50 years compared to those aged 50+), non-Whites, those currently employed, those reporting less than $60,000 in annual family income, and those living in Western provinces (British Columbia, Alberta, Saskatchewan and Manitoba) and Ontario compared to Quebec and the Atlantic provinces. In addition, rates of vaccine hesitancy were significantly higher among those without a health risk condition, those identifying as essential workers, those identifying as healthcare workers, and parents of children under 18. Finally, rates of vaccine hesitancy were significantly higher among those reporting getting the flu vaccine less than three times in the past five years (all p's <0.05).

Multivariable logistic regression analyses examining associations between vaccine hesitancy and sociodemographic and clinical variables across all surveys/time points are presented in Table 2 . Partially adjusted analyses revealed that women were 19% more likely to be vaccine hesitant (OR padj 1.19, 95% CI 1.08 -1.32), those aged less than 25 years (OR padj 2.07, 95% CI 1.74 -2.46) and 26-50 years (OR padj 2.,41 95% CI 2.16 -2.69) were 2.07 times and 2.41 times more likely to be hesitant compared to those aged 51 and over, and those who identified as non-White were 1.3 times more likely to be vaccine hesitant compared to Whites (OR adj 1.30, 95% CI 1.14 -1.49). Fully adjusted analyses revealed that in addition to women, younger age groups, and non-Whites, those with high school or less education were 1.15 times more likely to be vaccine hesitant compared to those with graduate or post-graduate degrees (OR adj 1.15, 95% CI 1.041-1.28), those earning less than $60,000 per year in household income were 1.42 times more likely to be vaccine hesitant that those earning $60,000 or more (OR adj 1.42, 95% CI 1.26-1.61), essential and healthcare workers were 1.44 (OR adj 1.44, 95% CI 1.21 -1.71) and 1.35 (OR adj 1.35, 95% CI 1.04 -1.75) times more likely to be vaccine hesitant respectively, compared to those not in those fields. Finally, parents of children under 18 were 1.51 times more likely to be vaccine hesitant compared to non-parents (OR adj 1.51, 95% CI 1.30 -1.75), and those reporting . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 11, 2021. ;  getting the flu vaccine three times or more in the past five years were 73% less likely to be vaccine hesitant compared to those reporting getting the flu vaccine less than three times in the past five years (OR adj 0.27, 95% CI 0.23 -0.30).

Perceptions of the importance of engaging in infection prevention behaviours preventive across the five surveys/time points is presented in Figure 3 . Overall, 76% of respondents reported believing that engaging in infection prevention behaviours was extremely important, though we observed significant variations in perceived importance over time. Perceived importance was highest at survey 1 (87%), which then dropped to 71.3% by survey 2 and remained generally stable across survey 3 (74.5%), 4 (75.7%) and survey 5 (71.3%).

Concern trends generally followed a similar pattern: mean values for each concern type were highest at survey 1, and dropped significantly by survey 2 and remained generally stable across survey 3 to 5 (p<.0001 for trend, see Partially and fully adjusted multivariate logistic regression analyses examining associations between vaccine hesitancy and perceived importance of engaging in infection prevention behaviours and COVID-19related concern types across all surveys/time points are presented in Tables 3 and 4 . Respondents who perceived engaging in infection prevention behaviours to be extremely important were 78% (partially adjusted) and 77% (fully adjusted) less likely to be vaccine hesitant than those who believed engaging in these behaviours was only somewhat, not very, or not at all important (OR padj 0.22, 95% CI 0.19 -0.25 and OR adj 0.23, 95% CI 0.20 -0.27, respectively). Although social and economy concerns were the most endorsed by respondents, they were not predictive of vaccine hesitancy in partially or fully adjusted analyses. However, health concerns were associated with a 58% (partially adjusted) and 54% (fully adjusted) reduced odds of vaccine hesitancy (OR padj 0.42, 95% CI 0.39 -0.46 and OR adj 0.46, 95% CI 0.42 -0.50, respectively), while having high personal financial concerns was associated with a 1.41 and 1.33 times greater odds of vaccine hesitancy in partially (OR padj 1.41, 95% CI 1.32 -1.49) and fully adjusted (OR adj 1.33, 95% CI 1.25-1.43) models.

The present study analyzed Canadian survey data from five age, sex and province-weighted populationbased samples to describe vaccine intentions between April 2020 and March 2021 and their correlates. Over 40% of Canadians reported some degree of vaccine hesitancy over the course of the study period. Vaccine . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 11, 2021. ;  hesitancy was lowest during pandemic waves one and three, and highest during pandemic wave 2, just prior to vaccine approval in Canada (December 2020). These results are consistent with data from the US covering the same time period, which also demonstrated significant increases in vaccine hesitancy between April and December 2020 among 8,167 online respondents in the Understanding America Study. 6 These results are also aligned with those of a study conducted by the World Economic Forum, which reported a decline in positive vaccine intentions between August (77%) and October 2020 (73%) among 18,526 respondents from 15 countries (including 1,000 from Canada) 17 .

We examined the profile of Canadians who were more likely to report being vaccine hesitant, and found that in fully adjusted analyses (including survey/time point), women, younger individuals (aged 50 and younger), non-Whites, those with lower levels of education (high school or less), and those reporting lower annual household incomes (less than $60,000/year) were significantly more likely to report being vaccine hesitant over the study period. Overall, this profile is consistent with the results of similar studies in Canada and other Western nations (e.g., USA, UK, France, Italy, Germany, and Australia) 18-28 suggesting a robust phenomenon of higher vaccine hesitancy among women, younger individuals, non-Whites, and those of lower socioeconomic status.

The reasons for the lower vaccine intentions among women remains poorly understood, and seems paradoxical given evidence that women are more adherent to COVID-19 prevention measures in general. 15, 29 Some speculate it might be related to their tendency to have greater health risk perceptions in general, 30 which may lead to heightened fears of experiencing vaccine side effects compared to men, resulting in less willingness to get vaccinated. These fears may not be completely unfounded, in light of evidence showing that women tend to have stronger immune reactions to vaccines than men, which may lead to more adverse events following vaccination. 31, 32 More recent data suggests that women may be more reluctant to get vaccinated due to reproductive factors, as women who are pregnant or planning to get pregnant appear to be delaying vaccination due to safety concerns affecting the fetus. 33, 34 Given evidence to suggest that pregnancy in the presence of COVID-19 may confer increased risk for severe illness, hospitalization and intensive care unit admission, and preliminary findings of no obvious safety concerns among pregnant women who received mRNA vaccines 35 , addressing vaccine hesitancy in this group will be important for protecting this vulnerable population.

Contrary to women, younger adults may be less willing to get vaccinated due to lower COVID-19 risk perception compared to older adults. 36 These perceptions may have been fueled by early reports of lower risks of COVID-19 hospitalization and complications among younger age groups. 37 While overall COVID-19-related mortality among those under age 20 remains low (proportion of all-cause deaths attributed to COVID-19 has . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 11, 2021. ; https://doi.org/10.1101/2021.11.10.21266174 doi: medRxiv preprint been estimated to be 0.48% 38 ), those aged 20 to 59 have accounted for 63% of all infections and 30% of all hospitalizations in Canada since the start of the pandemic. 39 This suggests that this age group remains an important vector community virus transmission, and a need to optimize vaccination uptake in this age cohort.

Our results also revealed lower vaccine intentions among non-Whites, those with high school or less education, and those with annual household incomes less than $60,000CAD/year (below the poverty line in Canada). 40 These results are consistent with those from previous studies in the US 18, 20, 21, 41 , Australia 25 , and across Europe 26, 27, 42, 43 . Results of greater vaccine hesitancy among people of color is a cause for concern, given that these individuals are more likely to work in industries worst affected by the COVID-19 pandemic, such as food and beverage, hospitality, and long-term care services. 44 Reasons for higher rates of hesitancy among these groups may include lower health literacy 45 and lack of trust in vaccines and the healthcare system, 46 the latter of which may be exacerbated by low representation of people of color in vaccine trials and experience with discrimination and systemic racism. 47 Clearly, greater efforts need to be made to motivate and enable those from racial and ethnic minority groups to get vaccinated.

We also identified two important groups of individuals at greater risk of being vaccine hesitant: essential and healthcare workers. Evidence of greater hesitancy among essential and healthcare workers was both surprising and a cause of concern, given that they are the individuals most likely to be exposed, and expose others to COVID-19. However, our results do seem to be in line with US data from a survey of 16,970 employed adults in the US showing that those working in essential service sectors (i.e., leisure and hospitality, manufacturing, construction, retail, transportation, and food and beverage) had the highest rates of vaccine hesitancy (45% to 54%) compared to non-essential sectors like technology (25%), financial services (26%), public administration (36%) and entertainment (37%). 48 Our findings of high vaccine hesitancy among healthcare workers is also consistent with other studies both within 49 and outside [50] [51] [52] of Canada. Though we were not able to determine what types of healthcare workers are more likely to be vaccine hesitant, data from previous reports suggests this is more common among female healthcare workers, 49,50,53 as well as nurses and paramedical professionals rather than physicians or health administrators. [51] [52] [53] While the reasons for vaccine hesitancy among healthcare workers remain poorly understood, available evidence suggests their hesitancy is linked to vaccine novelty and concerns about safety. 49, 52 Further research is needed to identify barriers to vaccination among essential and healthcare workers due to their high risk of virus exposure and transmission.

There were two additional findings from our analyses that warrant discussion. The first is that vaccine hesitancy was higher among those with an inconsistent history of getting the flu vaccine. This is consistent with previous reports 19, 41, 43, 54, 55 , and suggests that having favorable vaccine attitudes and behaviours in general is associated with greater likelihood of getting vaccinated against COVID-19. The other finding is that parents of children under age 18 were 1.5 times more likely to be vaccine hesitant compared to non-parents. Given the impending approval of vaccines among 5-11 year-olds in Canada, this finding is a cause for concern, and . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this this version posted November 11, 2021. ; https://doi.org/10.1101/2021.11.10.21266174 doi: medRxiv preprint consistent with at least one study out of the UK that also found that parents of young children were more likely to report vaccine hesitancy or refusal. 56 The reasons for this are remain poorly understood, but may reflect more general trends of parental hesitancy to vaccinate their children against common infectious diseases (e.g., mumps, measles, pertussis). 57 Given that COVID-19 infection rates are currently highest among school-aged children in Canada, 58 parents represent an important target for vaccination. Further research is needed to understand the reasons for vaccine hesitancy in this group and the impact of personal vaccine hesitancy on their willingness to get their children vaccinated against COVID-19, in order to optimise vaccination rates in this vulnerable group.

In addition to sociodemographic predictors, we also assessed psychological predictors of vaccine hesitancy. One of the strongest predictors of positive vaccine intentions was the extent to which Canadians believed engaging in preventive health behaviours (e.g., vaccination) was important for reducing virus transmission. Those who believed that engaging in preventive health behaviours (like getting vaccinated) was 'extremely important' were 77% less likely to be vaccine hesitant after adjustment for covariates including sociodemographics and survey period/time point. This finding is consistent with previous reports linking high perceived benefits (of getting vaccinated) to positive vaccine intentions, 59 highlighting the need for vaccination campaigns to clearly and consistently emphasize how the benefits of getting vaccinated far outweigh any risks.

We also found that different types of COVID-19-related concerns were important determinants of vaccine hesitancy. Interestingly, even though social and economy concerns were the most highly endorsed at each survey/time point, only high health-related concerns and personal financial concerns were significant predictors of vaccine hesitancy -but not in the same direction. In fact, we found that those with high health concerns (i.e., concerned about becoming infected and/or infecting others) were 54% less likely to be vaccine hesitant, while those with high concerns about their personal financial situation (e.g., were worried about job and income loss or not having enough money to feed their family) were 1.33 times more likely to report being vaccine hesitant. Results linking high health concerns to lower vaccine hesitancy are consistent with those of other studies in Canada, the US, Australia, and Europe 18, 20, 21, 23, 26, 55, [60] [61] [62] [63] , and provide further support of the need for vaccination campaigns to highlight how getting vaccinated is going to be health protective. However, to our knowledge, this is the first study to date to observe a link between high personal financial concerns and increased vaccine hesitancy, and suggests that those whose livelihoods were negatively impacted by the virus may be less willing or able to get vaccinated. Further research is needed to determine the extent to which this reflects a lack of motivation or desire to get vaccinated, or a perceived inability to get vaccinated due to practical barriers or limitations (e.g., lack of access to paid leave to get vaccinated).

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This study should be interpreted in light of some methodological limitations. First, although we included large, national samples of Canadians with representation across age, sex, and province, the absolute number of participants in certain provinces (e.g., Atlantic) was lower, making inter-provincial comparisons difficult. Second, the survey was only available in English and French, which may have led to an underrepresentation of certain non-native English or French speaking groups. Further, our surveys included fewer people of color, which may reflect participation on online panels, so results might not generalize as well to non-Whites. Third, since the surveys were voluntary and participants were drawn from a polling firm's subject pool, participation may have been subject to some degree of selection bias. Fourth, though this study presents data depicting vaccine intentions over time, it was drawn from three separate cohorts of online panels, so data reflect trends in vaccine intentions over time but not in the same individuals. Finally, data were self-reported, which may have been subject to social desirability bias. 64 However, the fact that the surveys were anonymous likely mitigated this limitation.

Despite some limitations, this study also had a number of important strengths. The study included a large sample size, respondents were well distributed across provincial regions, age groups, employment status and income compared to census data available through Statistics Canada, and there were equal proportions of men and women. This study also collected data during peak lockdown of the first wave (April 2020) through to end the third wave (end of March 2021) when vaccines started becoming available in Canada. This allowed for the assessment of changes in vaccine intentions over time across three critical waves of the pandemic in Canada. We used conducted principal component analysis to determine the structure of our concerns module, which was found to have excellent internal consistency, which is important for ensuring the validity of our results linking concern types to vaccine hesitancy. Finally, results reflect a sub-analysis of Canadian representative data from the iCARE study, which has collected data from more than 100,000 people from 190 countries to date alongside ongoing efforts to collect similarly representative samples in eight other countries (see: www.icarestudy.com). This will facilitate comparisons with international datasets to contribute important evidence to support the development and implementation of COVID-19 vaccine policy strategies worldwide.

Over 40% of Canadians reported some degree of vaccine hesitancy between April 2020 and March 2021. Vaccine hesitancy was lowest during pandemic waves one and three, and highest during pandemic wave 2, just prior to vaccine approval in Canada. Women, individuals aged 50 and younger, non-Whites, those with high school education or less, and those with annual household incomes below the poverty line in Canada (i.e., $60,000) were significantly more likely to report being vaccine hesitant over the study period. Three important . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 11, 2021. ; https://doi.org/10.1101/2021.11.10.21266174 doi: medRxiv preprint groups of Canadians were identified as being vaccine hesitant: essential and healthcare workers, parents of children under the age of 18, and those without a previous history of flu vaccination. Finally, perceived importance of engaging in infection prevention behaviours (like vaccination) and having high COVID-19-related health concerns were predictive of lower levels of vaccine hesitancy, whereas having high COVID-19-related personal financial concerns was predictive of higher levels of vaccine hesitancy. Overall, results point to the importance of targeting vaccine efforts to subgroups who may be socioeconomically disadvantaged, who also happen to be disproportionately represented in essential service occupations including healthcare. Finally, vaccine messaging should emphasize how the benefits of getting vaccinated (particularly to health) far outweigh the risks, particularly those associated with personal financial losses.

Future research is needed to monitor ongoing changes in vaccine intentions and behaviour, as well as to better understand motivators and facilitators of vaccine acceptance, particularly among vulnerable groups. Figure 3 . Perceptions of the importance of engaging in infection prevention behaviours (percentage of respondents reporting "extremely important", dashed line) and mean COVID-19 concern levels (solid lines) across the five surveys/time points 

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Social learning theory and the health belief model

The health belief model and predictions of health actions

Do COVID-19-related policy attitudes and concerns influence adherence to behavioural prevention strategies among Canadians? Findings from the International assessment of COVID-19-related Attitudes, concerns REsponses and impacts in relation to public health policies (iCARE) Study. Health Psychol. submitted

Heard immunity: effective persuasion for a future COVID-19 vaccine

Hesitancy towards a COVID-19 vaccine and prospects for herd immunity. Available at SSRN 3593098

Measuring the impact of COVID-19 vaccine misinformation on vaccination intent in the UK and USA

Correlates and disparities of COVID-19 vaccine hesitancy. Available at SSRN 3667971

Acceptability of a COVID-19 vaccine among adults in the United States: How many people would get vaccinated? Vaccine

Determinants of COVID-19 vaccine acceptance in the US

COVID-19 vaccine hesitancy and resistance: Correlates in a nationally representative longitudinal survey of the Australian population

Intention to vaccinate against COVID-19 in Australia. The Lancet Infectious Diseases

The French public's attitudes to a future COVID-19 vaccine: The politicization of a public health issue

Attitudes on Voluntary and Mandatory Vaccination against COVID-19: Evidence from Germany

A future vaccination campaign against COVID-19 at risk of vaccine hesitancy and politicisation. The Lancet Infectious Diseases

Gender differences in COVID-19 related attitudes and behavior: Evidence from a panel survey in eight OECD countries

Gender differences in risk assessment: Why do women take fewer risks than men? Judgement and Decision Making

Sex and Gender Differences in the Outcomes of Vaccination over the Life Course

Sex differences in vaccine-induced humoral immunity

COVID-19 vaccine hesitancy among reproductive-aged female tier 1A healthcare workers in a United States Medical Center

COVID-19 vaccine acceptance in pregnant women

Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons

Risk Perception of COVID-19 Infection and Adherence to Preventive Measures among Adolescents and Young Adults

COVID-19 in children and young people

Children and young people remain at low risk of COVID-19 mortality. The Lancet Child and Adolescent Health

A Critical Assessment of Canada's Official Poverty Line. Frasure Institute

Attitudes toward a potential SARS-CoV-2 vaccine: a survey of US adults

Social patterning and stability of COVID-19 vaccination acceptance in Scotland: Will those most at risk accept a vaccine? medRxiv

Public Willingness to Get Vaccinated Against COVID-19: How AI-Developed Vaccines Can Affect Acceptance

Vaccine hesitancy and health literacy

Covid-19 vaccine hesitancy among ethnic minority groups

UK Government Scientific Advisory Group for Emergencies. Factors influencing covid-19 vaccine uptake among minority ethnic groups

Essential Workers More Wary of Getting Vaccinated Despite Higher COVID-19 Risk

Covid-19 vaccine acceptance, hesitancy, and refusal among Canadianhealthcare workers: A multicenter survey

Assessment of COVID-19 vaccine acceptance among healthcare workers in los angeles

Assessment of knowledge, attitudes, and practices towards new coronavirus (SARS-CoV-2) of health care professionals in greece before the outbreak period

Quatar healthcare workers' COVID-19 vaccine hesitancy and attitudes: A national cross-sectional survey

Increases in a marker of immune system reconstitution are predated by decreases in 24-h urinary cortisol output and depressed mood during a 10-week stress management intervention in symptomatic HIV-infected men

Acceptance of COVID-19 Vaccination during the COVID-19 Pandemic in China

Public perceptions of COVID-19 in Australia: Perceived risk, knowledge, health-protective behaviors, and vaccine intentions

Anti-vaccine attitudes and risk factors for not agreeing to vaccination against COVID-19 amongst 32,361 UK adults: Implications for public health communications. Available at SSRN 3716874

Understanding vaccine hesitancy in Canada: results of a consultation study by the Canadian Immunization Research Network

COVID-19 daily epidemiology update

Understanding COVID-19 vaccine demand and hesitancy: A nationwide online survey in China

A National Survey Assessing SARS-CoV-2 Vaccination Intentions: Implications for Future Public Health Communication Efforts

Demographic and psychological correlates of SARS-CoV-2 vaccination intentions in a sample of Canadian families. medRxiv

What drives resistance to public health measures in Canada's COVID-19 pandemic? An online survey of Canadians' knowledge, attitudes, and practices

Individual preferences for COVID-19 vaccination in China

Measuring bias in self-reported data

The primary source of funding for the iCARE study has been primarily through re-directed funding associated