Barriers to adult vaccination in Canada: A qualitative systematic review

Background: In recent years, Canadian health care professionals have observed an increase in vaccine refusal. The objective of this study is to review published literature and identify the main themes related to vaccine hesitancy and barriers to vaccination in Canadian adults and recent immigrants. Methods: A qualitative systematic review was performed. A comprehensive search of MEDLINE (1946 to January 2021) and EMBASE (1974 to January 2021) was conducted to identify existing literature that addressed the primary research question. Studies were eligible for inclusion if the study population involved 1) the general population, 2) Indigenous populations, 3) recent immigrants to Canada or 4) Canadian health care professionals. Results: Thirty-four studies were included with a focus on the general population (n = 22), health care professionals (n = 10) and recent immigrant populations (n = 2). The most frequently reported barriers were lack of vaccine information (41%), lack of access to vaccination (38%), fear of adverse reactions (38%), financial reasons (29%), lack of awareness of vaccine existence (29%), antivaccine sentiments (24%), notion that older adults do not need vaccination (18%), misconceptions on vaccine effectiveness (12%), potential sexual health promotion stigma (6%) and fear of needles (3%). Interpretation: Barriers to vaccination among Canadians and recent immigrants continue to be a challenge in the health care system. Conclusions: The greatest yield in improving vaccination rates is likely to come from supporting vaccine-hesitant individuals in shifting their thinking to greater vaccine acceptance. Pharmacists are well positioned to address vaccine hesitancy and involvement through education, facilitation and administration of vaccines. Can Pharm J (Ott) 2022;155:xx-xx.


Introduction
Vaccines and vaccination programs prevent millions of deaths annually around the world. 1 In Canada, vaccines have eliminated, contained and controlled diseases that were once very common. 2 Unfortunately, vaccine hesitancy is on the rise in many countries, including Canada. 3 The World Health Organization defines Original research vaccine hesitancy as suboptimal vaccination coverage due to delay in acceptance or refusal of vaccines despite availability of vaccination services. 4 A 2018 survey of Canadian health care professionals reported that 26% of family physicians have observed an increase in vaccine refusal over the past 5 years. 5 The measles, mumps and rubella (MMR) vaccine had the highest rate of refusal, and the most common reason for refusal is knowing someone who has experienced an adverse effect from a vaccine. 5 Infants and children are particularly susceptible to vaccine-preventable diseases, and guidance is available for medical professionals to address parental vaccine hesitancy in primary care. 6 Immunizations are important for adults to restore waning immunity and to build new immunity against diseases that are more common in adults. 7 During the coronavirus disease 2019 (COVID-19) pandemic, understanding and addressing vaccine hesitancy to increase individual and herd immunity are important as vaccines become increasingly available. This article reviews the published literature and identifies the main themes related to vaccine hesitancy and barriers to vaccination in Canadian adults and recent immigrants to Canada. These findings can inform future vaccination initiatives and messages for undervaccinated Canadian adults.

Methods
This qualitative systematic review was performed and reported in compliance with the recommendations from the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA). 8

Search strategy
A comprehensive search of MEDLINE (1946 to January 2021) and EMBASE (1974 to January 2021) was conducted to identify existing literature that addressed the primary research question. The search terms and Boolean used in MEDLINE and EMBASE are outlined in Appendix 1.

Selection of studies
Studies of vaccine hesitancy and barriers to vaccination in Canada were eligible for inclusion if the study population involved 1) the general population, 2) Indigenous populations, 3) recent immigrants to Canada and 4) Canadian health care professionals. Exclusion criteria applied during preliminary screening were studies involving 1) pediatric patients, 2) parents' vaccine hesitancy and barriers towards vaccinating their children, 3) specific conditions (e.g., pregnancy, breastfeeding, rheumatoid arthritis, asthma) and 4) specific populations (e.g., sex workers). Two authors (DS, BG) screened the search results for potentially relevant studies. Potentially relevant citations were then reviewed in full to determine whether the predefined inclusion criteria were met.

Data extraction and management
Data from each included study were extracted and tabulated. Extracted data included authors, language, study design, year of publication, type of vaccine, study population, barriers to vaccination and limitations. Data were first extracted by 1 author (DS), then checked by the second (BG); disagreements or inconsistencies regarding data extraction were resolved by discussion and consensus.

Data analysis
Descriptive analyses were performed on data extracted from the included studies.

Results
The search results and flow diagram are outlined in Appendix 2, available at www.cpjournal.ca. The initial search yielded 428 studies, of which a total of 34 studies met the criteria and were included in this review (Table 1).  Among included studies, 22 (65%) focused on the general population, 10 (29%) focused on health care professionals and 2 (6%) focused on recent immigrant populations.
Of the 34 studies included in this review, 14 focused on barriers to human papillomavirus (HPV) vaccination and 12 on barriers to influenza vaccination. The remaining studies focused on multiple vaccines (4); tetanus, diphtheria and pertussis (Tdap) vaccine (2); hepatitis B vaccine (1) and measles vaccine (1).

Discussion
Current estimates are that up to 5% of the Canadian adult population has strong antivaccination views, while an additional 20% to 30% can be described as vaccine hesitant. 43 Vaccine hesitancy results in the refusal or delay in receiving vaccination. 4 Factors that contribute to vaccine hesitancy are a person's lack of confidence or trust in the vaccine and/or health care provider; complacency, where the person does not see a need for the vaccine or does not see the value of the vaccine; fear of needles, blood or side effects from vaccines; and perceived inconvenient access to vaccines. 44 The greatest yield in improving vaccination rates is likely to come from supporting the significant number of vaccine-hesitant individuals in shifting their thinking to greater vaccine acceptance, rather than expending disproportionate effort on the relatively small number of people with strong antivaccination views. This review revealed that a lack of vaccine information, poor access to vaccination, fear of adverse reactions, financial barriers, poor awareness of vaccine existence and antivaccine sentiments as the most common reasons for vaccine hesitancy.       Strategies and interventions aimed to address the barriers and themes identified in this study have been well described by various groups in the past. As part of their COVID-19 Working Group, the Royal Society of Canada outlines the responsibility shared by health care providers to actively support vaccine acceptance in their communities. 45 As accessible and trusted health care providers, pharmacists are well positioned to address vaccine hesitancy by providing patient education based on the best available evidence and discussing risks and benefits associated with vaccination. 46 Pharmacist involvement through education, facilitation and administration of vaccines has been shown to increase patient uptake of vaccination. 47 Prioritizing these roles and implementing strategies targeting known barriers and determinants of vaccine hesitancy could help to improve vaccine acceptance (Box 1).

Lack of vaccine information
The most commonly cited barrier to vaccination in Canadian adults is lack of vaccine information. Participants were aware of the existence of a vaccine but had no further information on its efficacy and safety, where to receive it, the cost or if it was necessary at all. Canadians have unrestricted access to high-quality, evidence-based vaccine information written in patient-friendly language, available from organizations such as Immunize Canada and the Public Health Agency of Canada. 48,49 Stakeholders should be focused on engaging Canadian adults in taking an interest in and seeking information about vaccines. Using a combination of interventions, such as face-to-face communication, health care provider training, community-based actions and mass media messages, appears to be much more effective than single-component interventions in raising awareness about vaccines. 50 Access to vaccination Unlike structured childhood vaccination programs, administration of adult vaccines in Canada is less routine and highly dependent on the actions of primary health care providers. 51 An important barrier to vaccination is lack of access to vaccination (mentioned in 38% of studies). This barrier can be addressed by informing and referring people to health care professionals who have access to vaccines and are authorized to provide vaccination services. Most recommended vaccines are Original research available at medical clinics, community pharmacies, community health centres, public health departments and travel clinics. Efforts are under way to evaluate an embedded community pharmacy-based approach aiming to improve vaccination rates in Canada utilizing pharmacist-delivered communicating and funding strategies. 52 According to 2018 Canadian survey data, more Canadian adults received their influenza vaccination at a pharmacy than any other location. 53 Recent reports highlight that pharmacists are well placed to improve access to vaccinations by using the annual influenza vaccination time to review and provide other adult immunizations as well. 54

Fear of adverse reactions
The second most common barrier identified was fear of adverse reactions. Despite overwhelming evidence supporting the safety of vaccines, lack of confidence in vaccine safety remains a major barrier to vaccination. Concerns range from fear of mild expected reactions such as injection site pain and redness to more serious but rare reactions such as anaphylaxis. Fears have been compounded by the spread of misinformation that vaccines can cause serious health problems such as developmental disorders or the very disease the vaccine is meant to protect against.
Seventy percent of Canadians use online resources for medical or health-related information. 55 Thus, educating patients and providing reliable sources of information may limit the need for Canadians to seek out information from unreliable Internet sources, which can be misleading or inaccurate.
Health care provider transparency about potential adverse effects can build trust and has been shown to lower perceived risk. 56 Furthermore, it has been demonstrated that providing information about the adverse reaction reporting system may increase trust and vaccine acceptance among adults. 57 Some individuals believe that the risk of contracting a vaccine-preventable disease is lower than the risks of experiencing a severe adverse reaction from a vaccine. A randomized controlled trial showed that stories and images highlighting the beneficial impact of vaccination on such diseases improved attitudes towards vaccination, especially among vaccine-hesitant individuals. Although encouraging, evidence is needed to confirm the effectiveness of storytelling in changing people's intentions to vaccinate. 58 According to a survey of primary care physicians in the United States, "the most common communication practices deemed very effective for convincing skeptical parents were personal statements by physicians about what they would do for their own children and about their personal experiences with vaccine safety among their patients. " 52 Similar strategies can help counter antivaccine sentiments, which was another prominent barrier in this review (24%). Additionally, health care providers should leverage their position as trusted vaccine resources for adults by discussing expected adverse reactions, explaining adverse reaction management and correcting misconceptions. Canadians identify health care providers (HCPs) as their most trusted source for vaccine information, and research has shown that HCP recommendations are one of the strongest predictors of vaccine acceptance. 59,60 Box 1 strategies to target known barriers and determinants of vaccine hesitancy • Prioritize role as vaccine educators and be prepared to provide information, correct misinformation and dispel myths.
 become familiar with the factors that contribute to vaccine hesitancy and how to best support patients depending on the specific concern or perceived barrier.  Ask open-ended questions and actively listen in order to identify specific patient concerns to ensure information is tailored appropriately.  Ensure you are current on latest vaccine information and be prepared to discuss benefits and risks of vaccines.  Present strong recommendations and share personal stories and experiences when able.  Have up-to-date and credible information readily available to provide patients.
• be proactive in starting conversations about vaccines, making this a routine part of your practice.
 Ask about vaccination status during all encounters and care activities and implement an immunization assessment to identify unmet needs.  Involve all pharmacy staff members in vaccine promotion by asking initial screening questions or identifying patients who have vaccine questions.  Adopt the mind-set that individuals are underimmunized unless you can confirm otherwise and hold the expectation that vaccination is the most probable outcome. • Ensure vaccination services are convenient and easy to access.  Provide options for both prebooked appointments and walk-ins, or refer to a provider who can administer a vaccine in a timely manner.  Keep a small quantity of routinely requested vaccines on hand to provide vaccinations opportunistically.  Offer additional routine immunizations when providing annual influenza vaccines.

Financial barriers
Financial barriers are important concerns that affect immunization coverage in Canada. Vaccine recommendations in Canada are made by the National Advisory Committee on Immunization (NACI), while vaccine programs along with the decisions on vaccine coverage are implemented separately by each province or territory. 61 Most vaccines are provided free for Canadians, as these vaccines have proven to be costeffective for the health care system. However, evaluation of the economic impact takes time and results in some new vaccines not being covered for all individuals. A practical cost consideration is lack of access to local clinics with open extended hours in a geographic area. As a result, patients have to plan ahead and consider taking time off work to follow the recommended vaccination schedule. 62 Most cost-associated barriers were in correlation with the HPV vaccination, as 1 dose of HPV costs about $185 and patients need 3 doses to gain immunity from 9 strains of HPV. 63 Influenza vaccination, when it is not publicly covered, costs about $25 to $30/dose. 64 Awareness of vaccine existence A survey conducted by Halperin et al. 39 revealed that knowledge among adults about the Tdap vaccine was low, and only 36% of participants reported being aware that Tdap was recommended for all adults. Results of a cross-sectional study by Tatar et al. 35 showed a positive correlation between HPV vaccine acceptance and knowledge about HPV and having discussed the HPV vaccine with their health care provider. Events such as the National Immunization Awareness Week (NIAW) help highlight the importance of immunization and the impact of vaccines on preventing illness and death. Multiple organizations in Canada and around the world participate in this annual event to raise awareness about vaccines and improve vaccination rates. The Canadian government has committed millions of dollars to immunization initiatives for surveillance, education, outreach and guidance on the use of vaccines. 65 A study conducted by Shen and Dubey 6 suggests patients are not discussing vaccines early enough with their health care providers. When pharmacists discuss vaccination status and provide information to patients, vaccination rates improve. 66 Resilience of older adults Immunosenescence, weakened immune function due to natural aging, results in increased susceptibility to infectious diseases, especially in those with underlying chronic illnesses. 67 As older adults are at higher risk of complications due to impaired immune function and comorbidities, it is essential to develop messaging and strategies to improve vaccine uptake in this population. 68 The misconception of natural immunity to the vaccine-preventable disease due to age can be addressed by health care professionals providing education on nonvaccination risks, as recommended by the Canadian Public Health Agency. 66

Limitations
This review had several limitations. As most of the included studies were related to influenza and HPV vaccines, which are inactivated, it is possible the barriers may differ if a live vaccine were evaluated, or for other types of vaccines. Furthermore, the barriers we found are a compilation of general public and health care professionals (who would presumably be better informed). When quantifying the barriers to vaccination, we reported crude rates of studies (rather than individuals) reporting the various barriers. Finally, this review does not include literature describing barriers to relatively newly developed vaccines, such as the COVID-19 vaccine.

Conclusion
Barriers to vaccination among Canadians and recent immigrants continue to challenge our health care system and contribute to vaccine hesitancy. Although decision-making regarding vaccination is complex and can be impacted by a number of factors, awareness of common barriers to vaccination has informed the development of strategies to improve vaccination uptake. Interventions to support vaccine-hesitant Canadians require effort and collaboration across all levels of our health care system. As trusted and accessible professionals, pharmacists are encouraged to incorporate vaccine assessments, preventive health and educational initiatives in their practice that may improve accessibility to vaccine services. ■