Attitudes, barriers, and facilitators to adherent completion of the recombinant zoster vaccine regimen in Canada: Qualitative interviews with healthcare providers and patients

ABSTRACT

This qualitative, cross-sectional study aimed to understand the barriers and facilitators related to the adherence and completion of the recombinant zoster vaccine (RZV) two-dose series in Canada, as perceived by healthcare providers (HCPs) and patients. Data collection occurred via 60-minute concept elicitation interviews with 12 HCPs (4 physicians, 2 nurse practitioners, 6 pharmacists) who had prescribed and/or administered RZV in Canada, and 21 patients aged ≥50 years who had received ≥1 dose of RZV. Patients were categorized as adherent (received both doses within the recommended 2-to-6-month timeframe; n = 11) or non-adherent (received only one dose or second dose outside the recommended timeframe; n = 10). Interview transcripts were coded and analyzed using a two-part thematic analysis approach. HCP-identified barriers to RZV adherence included high out-of-pocket cost, inconsistent/lack of health plan coverage, inconvenient processes for accessing RZV, and patient forgetfulness. HCP-identified facilitators included desire for shingles protection, HCP encouragement, and reminders. Barriers to RZV adherence identified by patients included lack of HCP knowledge/experience with RZV, receiving unreliable/confusing information, having unpleasant/severe side effects following the first dose, high out-of-pocket cost, lack of insurance coverage, and forgetfulness. Patient-identified facilitators included self-motivation, financial support, convenient processes for obtaining RZV, and reminders. In conclusion, many factors can influence RZV series completion and adherence among adults in Canada, including cost, insurance coverage, HCP knowledge and encouragement, and reminders. Awareness of these factors may inform HCPs in helping patients overcome barriers and identify opportunities for future consideration, facilitating protection against herpes zoster.

GRAPHICAL ABSTRACT

KEYWORDS:

• Canada
• herpes zoster
• vaccines
• varicella zoster virus

Introduction

Reactivation of the varicella-zoster virus (VZV; chickenpox) in previously infected individuals can cause herpes zoster (HZ; shingles), which is characterized by a painful vesicular rash.¹ Given the natural decline in immune function with age, individuals aged ≥50 years are at increased risk of developing HZ, as are those who are immunocompromised due to disease or therapy.²

Over the last few decades, HZ incidence has increased globally, largely due to an aging population.³ In Canada, overall HZ incidence in individuals increased from 3.2 to 4.5 per 1000 population from 1997 to 2012. The highest increases in incidence were in those aged 40–49 (2.4 to 3.9 per 1000 population) and 60–69 years (5.4 to 8.7 per 1000 population); HZ incidence was highest in adults aged ≥80 years in 2012 (11.1 per 1000 population).⁴ Annual HZ-related costs in Canada for hospitalizations and primary care visits over this time period were $4.9 million and >$500,000, respectively, indicating a significant burden on the Canadian healthcare system.⁴

Vaccination is considered the best intervention to reduce the health and economic burden of HZ.^5,6 The Canadian National Advisory Committee on Immunization (NACI) strongly recommends that adults aged ≥50 years receive the two-dose recombinant zoster vaccine (RZV; Shingrix) to obtain protection against HZ.⁷ In Canada, RZV can be administered in health clinics or pharmacies. At the time of publication, public funding for RZV is only available in four provinces (Ontario, Quebec, Prince Edward Island, Yukon) for specific older adult age cohorts, and in Alberta for solid organ transplant candidates. Quebec also provides funding for immunocompromised individuals aged ≥18 years. Some federal government programs provide RZV free to adults of certain demographic backgrounds (e.g., veterans, incarcerated populations, First Nations and Inuit populations) or with immunocompromising conditions at a high risk of developing HZ. Otherwise, RZV is available out-of-pocket for approximately $150 CAD per dose, with the cost fully or partially covered by some private insurers.

NACI recommendations specify that the second RZV dose be administered 2–6 months after the first, though the second dose may be given up to 12 months after the first for improved adherence.⁷ However, a recent study has shown that only 65.0–74.9% of Canadian adults who received one RZV dose completed the two-dose regimen within 2–12 months.⁸ Although NACI states that the RZV series does not need to be restarted if the second dose is not administered within the recommended timeframe, maximum protection against HZ is not attained until series completion.⁹ Therefore, this gap in adherence suggests that almost a third of adults who have received RZV only received one dose, and are thus not fully protected against HZ.

Researchers have identified multiple factors that affect HZ vaccine uptake and acceptance, including cost, accessibility, recommendation from healthcare providers (HCPs), previous experience with HZ, knowledge and perceived risk of contracting HZ, concerns about side effects, and awareness of vaccine safety and effectiveness.^10–14 Key social determinants of health can also influence HZ vaccine uptake and adherence, including gender, ethnicity, income level, and education level.^15–18 Nevertheless, there is a paucity of literature on the factors influencing completion and adherence of RZV specifically. An increased understanding of these factors may help identify improved strategies to overcome barriers. This study aimed to elucidate HCP and patient attitudes toward RZV, and to explore the barriers and facilitators related to the completion of and adherence to the RZV two-dose regimen in Canada.

Methods

Study design

This study used a cross-sectional design with qualitative data collection and analysis methods. A targeted literature review was conducted to identify common barriers and facilitators to vaccine completion and adherence in adults. The search, conducted using PubMed, focused on articles written in English and published internationally between August 2015–August 2020. Data were extracted from articles specific to HZ, HZ vaccines, and barriers and facilitators to HZ and other multi-dose series adult vaccinations.

Patient-provided barriers identified in the literature included: concerns about vaccine cost, fears related to vaccine safety, side effects, or needles, low perceived likelihood of contracting the infection or getting severe disease, lack of HCP knowledge or recommendations, and distrust of HCP recommendations. Facilitators included: HCP recommendations, socioeconomic factors, race/ethnicity, access to regular care or existing relationship with an HCP, past positive experiences with vaccines, high perceived likelihood of contracting the infection or getting severe disease, and presence of comorbidities. The literature on HCP-provided barriers and facilitators identified many of these factors, but added the role of the organization and the availability of resources and support as another factor. These findings informed development of the study protocol and other study materials, such as shaping the interview questions and the content of the recruitment messaging and consent form.

The study team conducted two rounds of concept elicitation interviews in both English and Canadian French. The first round of interviews included HCPs (primary care providers and pharmacists) who had prescribed and/or administered RZV in Canada. These interviews aimed to confirm the attitudes, barriers, and facilitators identified in the literature and to identify new facilitators and barriers among Canadian HCPs. The second round of interviews included patients aged ≥50 years who had received one or both doses of RZV. Patient interviews allowed patients to share their experiences with RZV, further confirming and/or elaborating on the barriers and facilitators identified in the literature and HCP interviews. HCPs and patients were compensated for their participation according to fair market value.

Ethics approval for this study was granted by the WIRB-Copernicus Group Institutional Review Board (IRB; tracking number: 20210320) on 1 March 2021. Before being interviewed, all participants received and reviewed an IRB-approved informed consent form with a description of the study, study procedures, risks and benefits, and details on whom to contact with questions.

Interviews

Healthcare provider recruitment

Using purposive sampling, potential study participants were identified and recruited from pre-existing Canadian HCP panels. Potential participants were screened against pre-defined inclusion/exclusion criteria and, if eligible, scheduled for a virtual interview.

Eligible HCPs must have provided care for patients aged ≥50 years in Canada, have previously prescribed and/or administered RZV, and be able to speak, read, and understand English or Canadian French. Efforts were made to include an HCP from every Canadian province or territory to account for potential geographical differences.

Patient recruitment

Patients were also recruited using purposive sampling through multiple recruitment sources, including pre-existing patient panels, physician referrals, targeted social media ads on Facebook, and direct advertising from CanAge, a national senior advocacy organization in Canada. Potential participants were screened by telephone and required to provide proof of their RZV vaccination status to establish eligibility. Eligible patients were scheduled for an interview.

Eligible patients must have been aged ≥50 years, have received one or both doses of RZV between January 2018–February 2020, reside in Canada, and be able to speak, read, and fully understand English or French. The selected timeframe for vaccination captured patients who received both doses of RZV before the start of the COVID-19 pandemic and those who were eligible to or received the second dose during the pandemic.

Eligible patients were categorized as “adherent” if they received both doses within 2–6 months, in alignment with NACI recommendations, and “non-adherent” if they had either received only one dose or the second dose outside the recommended timeframe.

To ensure adequate representation of both adherent and non-adherent patients, efforts were made to diversify the sample across number and timing of RZV doses, income, insurance coverage, sex, race/ethnicity, and education.

Data collection

Each 60-minute, individual interview was conducted by a trained, qualitative researcher from the study team. Interviews were conducted by telephone or webcam and followed a semi-structured interview guide, which was developed for this study and tailored to HCPs or patients. All interviews began with broad, open-ended, non-leading questions (available upon request from the corresponding author) that enabled participants to list their personal barriers and facilitators, followed by probing questions to learn more about those that were identified in the literature and/or confirmed by HCPs in the first round of interviews. This combination of pre-set questions and ad hoc follow up enabled the collection of full and rounded descriptions of barriers and facilitators to RZV adherence. All interviews were audio recorded and transcribed verbatim.

Data analysis

Interview transcripts were coded and analyzed in NVivo software (v.12; QSR International Pty Ltd., 2018) using a thematic analysis approach that included inductive and deductive coding.^19,20 This ensured both known and new concepts related to attitudes, barriers, and facilitators of RZV completion and adherence were captured. The first three HCP and first eight patient interview transcripts were coded independently by two members of the study team. The coding structure was then reviewed by the study team to establish inter-rater reliability, where discrepancies or issues in coding were resolved through discussion. Once the study team was confident that the coding approach was consistent, the same two study team members coded the remaining transcripts. A third study team member contributed to coding patient interview transcripts after being fully oriented to the process. Saturation analyses confirmed the sufficiency of HCP and patient sample sizes, and adverse events reported during patient interviews were reported to the appropriate authorities (further details in Supplementary Materials).

Results

Participant characteristics

Healthcare providers

In total, 12 HCPs (4 physicians, 2 nurse practitioners, 6 pharmacists) were interviewed (Table 1). At least one HCP per geographic region was included. All HCPs had cared for patients aged ≥50 years and had experience administering RZV; seven had previously prescribed RZV.

Table 1. Healthcare provider participant characteristics.

	n (N = 12)
Type of Provider
Pharmacist	6
Physician	4
Nurse practitioner	2
Experience with RZV
Have administered the vaccine	12
Have prescribed the vaccine	7
Workplace
Pharmacy	5
Physician’s office	5
Hospital	1
Other	1
Geographic Region
Atlantic Region	2
Central – Quebec	3
Central – Ontario	1
Northern Territories	1
Prairie Provinces (Saskatchewan/Alberta/Manitoba)	3
West Coast	2
Language
English	9
Canadian French	3

RZV: recombinant zoster vaccine.

Patients

Patient participants included 21 adults aged ≥50 years who received at least one dose of RZV; approximately half were non-adherent (10/21), and most were female (14/21; Table 2). At least one patient for each geographic region was included, except for the Northern Territories.

Table 2. Patient participant characteristics.

	n (N = 21)
Age (years)
50–64	15
≥65	6
Sex
Female	14
Male	7
RZV Doses Received and Timing
2 doses, during recommended timeframe	11
2 doses, outside of recommended timeframe	3
1 dose only	7
Setting where RZV was Administered
Pharmacy	6
Physician’s office	10
Hospital	0
Other (clinic/travel clinic)	5
Geographic Region
Atlantic	3
Central – Quebec	7
Central – Ontario	5
Northern Territories	0
Prairie Provinces (Saskatchewan/Alberta/Manitoba)	3
West Coast	3
Highest Level of Education
No certificate, diploma, or degree	1
Secondary (high) school diploma or equivalency certificate	2
Apprenticeship or trades certificate or diploma	2
College, CEGEP or other non-university certificate or diploma	4
University certificate or diploma below bachelor level	7
University certificate, diploma, or degree at bachelor level or above	5
Health Coverage Status
Private health insurance through employer	20
Provincial or Territorial Public Health program	0
NIHB program	0
No coverage	1
Other	0

CEGEP: collège d’enseignement général et professionnel; NIHB: non-insured health benefits; RZV: recombinant zoster vaccine.

Patients reported having had RZV administered in a variety of settings, including at a physician’s office (10/21), pharmacy (6/21), or clinic (5/21; Figure 1). While most patients had supplemental private insurance through an employer (20/21; Table 2), many paid for both RZV doses out-of-pocket either fully (adherent: 5/11; nonadherent: 2/10) or partially (adherent: 4/11; non-adherent: 5/10) for costs not covered by insurance. Two adherent and three non-adherent patients had no out-of-pocket costs.

Figure 1. Self-described patient (N = 21) pathways to obtaining RZV.

Patient pathways for obtaining RZV can vary based on private or public access to the vaccine and multiple pathways may exist in a single province. HCP: healthcare provider; RZV: recombinant zoster vaccine. Created using Microsoft PowerPoint.

Results of adverse event reporting can be found in the Supplementary Materials.

Healthcare provider interviews

Knowledge and attitudes towards RZV

All HCPs demonstrated thorough knowledge of RZV, mentioning awareness of published efficacy rates, the recommendation to vaccinate adults aged ≥50 years, the two-dose requirement, and risk of some side effects. Two HCPs wanted more specific information on RZV, including whether the series must be restarted if the second dose is not administered within a certain timeframe, how long protection against HZ lasts, and whether a booster will be required in the future.

HCPs’ overall attitudes toward RZV were positive; most described the efficacy of the vaccine (9/12) and minimal/mild side effects (6/12) as favorable. Five HCPs also mentioned ease of administration and access. Six pointed out that HZ prevention, provided by RZV, is preferable to HZ treatment.

HCPs mentioned that some patients lacked information on potential side effects (5/12) and that negative experiences following the first dose could deter patients from getting the second dose. Four HCPs expressed concern about possible side effects, particularly the more severe swelling at the injection site that some patients experience. Additionally, few HCPs considered the inability to prescribe RZV to adults aged <50 years as a drawback since younger populations are also at risk of developing HZ (3/12).

Contraindications to RZV, described by HCPs as being immunocompromised, on an immunosuppressant, or allergic to a component in RZV, were consistently stated as the only cases in which HCPs would not recommend RZV. However, providers noted that they encourage contraindicated patients to speak with their specialists about getting RZV. HCPs also noted that they would communicate with specialists directly to determine if RZV can be administered safely to a patient.

Perceived barriers to RZV regimen completion

Selected quotes from HCP interviews illustrating various barriers and facilitators are presented in Table 3. Barriers to RZV completion and adherence expressed by HCPs included perceived high out-of-pocket costs (9/12) and inconsistent coverage by insurance companies or public health authorities (4/12; Figure 2a). According to HCPs, these factors particularly affect patients with a low income or on a fixed income, which is the case for many adults aged ≥65 years.

Figure 2. Barriers and facilitators to RZV adherence identified from HCP and patient interviews.

Non-adherent participants described the actual barriers that prevented them from completing or adhering with the recommended RZV regimen, while adherent patients described potential barriers that could have, but ultimately did not, prevent them from adhering to the RZV regimen (underlined). A: adherent; HCP: healthcare provider; HZ: herpes zoster; N: number; NA: non-adherent; RZV: recombinant zoster vaccine. Created using Microsoft PowerPoint.

Table 3. Selected quotes from HCP interviews illustrating various identified barriers and facilitators to RZV completion and adherence.

Theme	Illustrative quote(s)
Barriers
High out-of-pocket costs and/or lack of insurance coverage	“Because my demographic population [seniors] is very, very used to getting things for free … so, like, their, I guess, medical therapy, yes. [So] whenever there is a cost associated with something – and this is, I’ve spent a lot of time saying this to third party payers that don’t pay for vaccines – you’re actually doing a huge disservice. Because not only, uh, is the patient hesitant about paying, they think because the third party – or the government – isn’t paying, that it [the vaccine] doesn’t work, or … it’s not good, right? Otherwise, it would be paid for, right? So, overcoming that stigma as well is not, not always easy.” – Pharmacist
Inconvenient processes in accessing and stocking RZV	“If [my patients] live too far from my clinic, we can have it done [administered] through the pharmacy. So, that’s a bit easier for some too … [but] if we had it in our clinic and we were able to sell it and stock it, and there’s an incentive to family doctors to give it, then I could see more patients , out of convenience, would be [like], ‘Ooh, how much? Yeah, sure, I’ll get it while I’m here.’ – Physician
Patient forgetfulness and/or lack of second dose reminders	“My last location was ridiculously busy, and we didn’t do things like follow ups. We didn’t put it on our computer system. We kind of just left that to the patients to call us and say, ‘Hey I need this, I need my second dose.’ And people forgot about them. It wasn’t, you know, and it would be, you know, a year later and you’re looking like ‘Oh my God, you never got your second dose, right?’ – Pharmacist
Scheduling factors, e.g., travel, snowbirds^a	“The only thing, sometimes if we do the vaccines in October, people that get the vaccine the same time as the flu season. Last year there was not this problem, but years before, there [are] the snowbirds. The seniors always go South [for the winter]. And they need to be back in time for their second shot. Definitely, I cannot schedule for the two months because they are still away. And then it’s close to the six months. So, they really need to come when we call.” – Pharmacist
Missed or delayed second doses due to COVID-19	“So, what happened there was, now pharmacists that were really doing a lot more clinical stuff almost reverted back ten years to just really focusing on just getting patients their medication. So, when that happens, there’s lost opportunities as well. Because you’re not having the medication reviews, all these other things, where, you know, uh, the vaccine may have come up.” – Pharmacist “We are doing a lot of deliveries of medications. So, we don’t talk to the patient as much to recommend and counsel on immunizations.” – Pharmacist
Facilitators
Flexibility provided by the recommended 2-to-6-month timeframe for the second dose	“So, two months is a great place to start because it gives us four months to really, um, get it within the, the dosing schedule. And if, even if they, like if they went away — which they’re not going away these, you know, the last year or so [during the COVID-19 pandemic] — but if they were going away … it still gives us time to get in touch with them. And if it’s past that time, we still do the second dose.” – Pharmacist
COVID-19 vaccines normalizing the idea of multi-dose series vaccines	“I think it’s probably actually going to increase the compliance because I, everybody, is, is all on board now recently. ‘Okay. I want to get everything I can to make sure that I’m going to be safe and that I can travel and that I can do things and I’m not going to have any problems.’ I mean, I, I work at noon today and we actually have two Shingrix bookings for this afternoon, um … Friday I think we have another, a booster [second] dose for Shingrix. So, again, I think people are just wanting to get everything they can to make sure that they’re safe and healthy.” – Pharmacist

^aSnowbirds refer to people who travel to warmer locales for the winter. HCP: healthcare provider; RZV: recombinant zoster vaccine.

HCPs described factors unique to their geographies that may impact RZV coverage. For example, some provincial governments make age-based recommendations while others waive or subsidize the cost for small, high-risk population groups (e.g., adults aged 70–75 years of First Nations, Métis, or Inuit populations, chronically ill and low-income individuals). Additionally, pharmacists noted that the ability to prescribe RZV varies per region.

Issues surrounding access to RZV were viewed by HCPs as barriers to vaccine completion. For example, some HCPs noted that not all clinics or healthcare practices stock RZV (4/12), in which case patients had to visit pharmacies to obtain it and then take it back to their primary care provider to be administered.

Some HCPs noted that patient forgetfulness was a barrier to completion and adherence (5/12); one pharmacist from the Atlantic region described the lack of a follow-up appointment system as a hindrance (Table 3).

Two HCPs noted that scheduling factors can influence RZV completion since patients who travel, leave the area for months at a time (e.g., “snowbirds,” or people who travel to warmer locales for the winter), or move away may be less likely to adhere to the recommended dosing schedule.

Lastly, many HCPs theorized that the COVID-19 pandemic may have resulted in delayed or missed second doses for some patients (10/12), as lockdown measures imposed from March 2020 reduced in-person and non-essential visits to providers. Two HCPs further stated that the timing requirements for co-administration of multi-dose COVID-19 vaccines with RZV may have affected adherence to the recommended RZV schedule.

Perceived facilitators to RZV regimen completion

According to HCPs, the most important facilitator for completing the RZV series as recommended was the desire to gain protection against HZ (5/12; Figure 2a). Encouragement and education from HCPs were also notable factors; nearly all providers reported emphasizing the importance of completing the RZV regimen when speaking with patients (11/12).

Many HCPs mentioned the importance of reminders (8/12); most agreed that reminders from pharmacies, practices, or clinics were essential in ensuring patients complete the RZV regimen within the recommended timeframe. Additionally, providers expressed that the 2-to-6-month window may facilitate adherence as it allows flexibility for patients to finance and schedule the second RZV dose.

HCPs suggested that RZV completion may be improved with increased HCP-provided education on RZV (11/12), easier access/more convenient ways to obtain RZV (1/12), and reduced/subsidized vaccination costs (1/12). HCPs theorized that COVID-19 vaccines helped normalize the idea of two-dose vaccine regimens among patients; most providers reported observing increased interest among older patients in preventive healthcare (11/12), as the COVID-19 pandemic has emphasized the vulnerability of older individuals.

Patient interviews

Knowledge and attitudes towards HZ

Patients identified multiple sources from which they learned about HZ, including friends, family, or significant others (17/21), their HCP (4/21), and online searches (2/21). Three patients reported learning about HZ after experiencing it themselves; two of these patients received both RZV doses, while the third contracted HZ after the first dose and did not complete the RZV series.

More than half of the patients reported feeling at high risk of developing HZ (13/21), stating reasons such as being an older adult, having a history of VZV infection and/or a weakened immune system, family history of HZ, or having unhealthy behavioral habits (e.g., high-stress lifestyle, poor sleep). Of the 13 patients who considered themselves at high risk of developing HZ, 6 were non-adherent.

Knowledge and attitudes towards RZV

Patients reported learning about RZV from several sources, including their HCP (20/21) and online sources (15/21), such as various websites (e.g., shingrix.ca, Google, Government of Canada) and online publications (e.g., medical journals). Other sources included marketing materials or the media (13/21) and friends, family, or significant others (9/21). According to patients, their physician was the most trustworthy source of information about RZV (14/21), followed by online medical journal articles (5/21), and friends and family (4/21).

While most patients expressed indifference toward the RZV recommendations, more than half of the non-adherent patients considered the two-dose requirement inconvenient (6/10) and some thought that the time between doses was too long, which may increase the likelihood of forgetting to take the second dose (4/10). Three non-adherent patients also expressed their belief that one dose provides adequate protection. One non-adherent patient from Ontario noted:

”[I thought] one dose is as good as two doses … that is what caused a little bit of negligence on my side and I was like … ‘maybe one dose is good enough for me to, to cover me to some extent.’”

For most patients, HZ prevention (18/21) and encouragement from family, friends, HCPs, and coworkers (18/21) were important factors influencing their decision to obtain RZV. Many patients also explained that knowing whether their insurance fully/partially covered the costs of RZV contributed to this decision (11/21).

Barriers to RZV regimen completion

Selected quotes from patient interviews illustrating various barriers and facilitators are presented in Table 4. For some non-adherent patients, their perception that their HCP lacked knowledge and/or experience with RZV contributed to them not receiving the second dose at all or within the recommended timeframe (4/10; Figure 2b). These patients mentioned that their HCP did not stress the importance of receiving the second dose to gain full HZ protection. Lack of HCP knowledge and/or experience was also stated as a potential barrier among adherent participants (2/11). Several non-adherent patients (6/10) described receiving unreliable or confusing information about RZV from their physician, family, and acquaintances, which kept them from completing the regimen.

Table 4. Selected quotes from patient interviews illustrating various identified barriers and facilitators to RZV completion and adherence.

Theme	Illustrative quote(s)
Barriers^a
Lack of HCP-provided education or encouragement	“So, I figured I was okay with one [dose]. I never really questioned it. I know that the other, like my husband I think he had two, but I had one, and, uh, I guess [my physician] thought that was enough because of me having chickenpox when I was younger. I don’t know. But she didn’t push it.” – Non-adherent patient, one dose only
Receiving unreliable or confusing information about RZV	“I think that sometimes ‘they’ [drug manufacturers] overdo it. Meaning one dose is as good as two doses. Um, so, yeah. That is what caused a little bit of negligence on my side and I was like, I said, you know, among all those, um, reasons, also I was, I’m thinking down like ‘maybe one dose is good enough for me to, to cover me to some extent’ … meaning one dose is enough. In all honestly, one dose could be enough.” – Non-adherent patient, one dose only
High out-of-pocket costs and/or lack of insurance coverage	“Well, that kind of leads into why I didn’t get the second dose. And that was because my insurance company stopped covering vaccines. And so, I couldn’t afford to get the second dose … it [the cost] was high. And, for instance, my mom wanted to get it. She’s a senior and on fixed income. And she wanted to get it, but because it wasn’t covered, she didn’t get it.” – Non-adherent patient, one dose only “Well, like I said earlier, like, I would have done it anyways. But, but, you know, I’m coming from a point – a place of privilege. I can afford to pay for it. So, for me personally, it [the cost] didn’t make a difference, but I absolutely believe it makes a difference for others. Um, and, you know, having access to an extended health plan that will cover vaccines.” – Adherent patient
Unpleasant or severe side effects	“The side effects were really bad. I was supposed to go to a funeral service, and I couldn’t go. I felt horrible. I had a fever, I was aching all over, I was dizzy. I felt horrible. I couldn’t get off the sofa I felt so awful … I think I was also kind of wary after my reaction to it. That didn’t sort of, it was kind of like, ‘Oh, I’m going to spend over $200 to get really sick?’ Like, I was not looking forward to another reaction like that.” – Non-adherent patient, one dose only
Patient forgetfulness	“Given the time frame [between the first and second shots], it is something you are able to forget. Thankfully, they called me back, as it is true that it is something that I might have missed. Even if I did not want to miss my second dose, I could have missed it if they did not call. The fact that they called me made a difference. I’m not sure I would have remembered…” – Non-adherent patient, two doses outside recommended timeframe
Inconvenient processes in obtaining and accessing RZV	“I think the only thing that would’ve made the whole process easier would be, as I said previously, [if] the family doctor had it on site and I didn’t have to go take that trip to the pharmacy first. But as I said, I’m not sure if that can be changed. So that would be about the only thing that I would’ve changed, and it certainly would’ve been easier.” – Adherent patient
Facilitators
Self-motivation and/or viewing the investment for RZV as an investment in themselves/their health	“The pharmacist gave me the dose, gave me the injection. But the physician … never even asked afterward if I followed through. So, it was me making sure I showed up for the second dose injection.” – Adherent patient “Because if you think about it, you’ve had the first shot. You’ve already invested the, you know, 130 bucks or whatever it was … Then it’s a waste of your investment if you don’t follow through.” – Adherent patient
Desire to gain full protection against HZ	“So, you know, like I said, when it comes to preventative measures, I’m all over it. Like, I’m not going to – I don’t want to be that person who can’t live a normal life, per se. I want to be able to – you know, I’m at that age where you start to think about your mortality. And I still have a lot of stuff I want to do. So, I’m not going to spend it being miserable and sick if I can help it.” – Adherent patient
Knowledge of the high effectiveness rate of RZV	“I was more concerned … truly my concern was, you know, ‘how well does this work?’ Because I had discounted the previous one [Zostavax] saying ‘this isn’t worth it,’ you know? It, it doesn’t work well enough that I’m going to jump on the wagon. So, the fact that this had a higher percentage of success is ultimately – yeah, I would say that’s what pushed me toward it.” – Adherent patient
Convenient processes in obtaining RZV	“I made an appointment. And she [the nurse] went through the consent form, and I got the immunization. I waited in the office, I think, for 15 minutes, and made the second appointment at that time. And it was fine. It was easy … There was no difficulty whatsoever.” – Adherent patient
Second dose reminders	“It’s just like for anything … When you go and get the first dose, it [the reminder system] initiates a countdown, and I presume that the best way to ensure that the second dose is given is for the clinic to inform us of the time period during which we have to receive it. Then, we choose a date that fits during that period, we write it down on the piece of paper. ‘Do you want us to call you back?’… However, maybe they [the pharmacy] will feel obliged to confirm, maybe they will confirm, as maybe they will have to close down for some reason or other, or they have stock problems … there is a question of synchronization that can be done, as there are always potential unplanned events.” – Adherent patient

^aNon-adherent participants described the actual barriers that prevented them from completing or adhering with the recommended RZV regimen, while adherent patients described potential barriers that could have, but ultimately did not, prevent them from adhering to the RZV regimen. HCP: healthcare provider; HZ: herpes zoster; RZV: recombinant zoster vaccine.

Prioritizing other vaccinations (e.g., COVID-19) that felt more urgent was a barrier to completion for two non-adherent patients. Two adherent and one non-adherent patient further hypothesized that, before the COVID-19 pandemic, busy schedules or frequent travel could have been barriers to scheduling the second dose. Two other non-adherent patients stated that a fear of needles kept them from getting the second RZV dose, while another attributed not obtaining the second dose to mistrust of recommendations from pharmaceutical companies.

Many patients mentioned the out-of-pocket cost of RZV (adherent: 9/11; non-adherent: 6/10) and lack of medical or insurance coverage (adherent: 6/11; non-adherent: 3/10) as real or potential barriers to adherence (Figure 2b). These barriers kept two non-adherent patients from getting the second dose (Table 4).

Although four non-adherent patients experienced side effects from RZV, only one of these patients cited unpleasant or severe side effects as the reason why they opted to forgo the second dose. Seven adherent patients reported experiencing notable side effects from the first dose, which they hypothesized could have been a barrier, but ultimately did not stop them from completing the two-dose regimen. Additionally, three non-adherent patients mentioned that forgetfulness and lack of reminders from providers resulted in delayed or missed second doses.

Adherent patients described additional barriers that could have, but ultimately did not, prevent them from completing the RZV series, including inconvenient or unfamiliar processes of receiving RZV (5/11; Figure 1) and limited RZV availability in physicians’ offices, clinics, or pharmacies (5/11).

Facilitators to RZV regimen completion

All adherent patients reported being self-motivated and/or viewing the “investment” in RZV as an investment in themselves/their health (11/11), while only 3/10 non-adherent patients expressed the same sentiment (Figure 2b). Many adherent patients were eager to get full protection from HZ by receiving both doses (8/11), whereas few non-adherent patients expressed the same motivation (3/10). Some patients mentioned that their self-motivation was driven by fear of contracting HZ after hearing “horror stories” from others (adherent: 4/11; non-adherent: 1/10). Only adherent patients described the high effectiveness of RZV (7/11) and feeling at risk of getting HZ (2/11) as motivation to adhere to the two-dose regimen.

Three adherent patients suggested that the cost of RZV was less than that of treating HZ, which may necessitate lost workdays, hospital visits, and/or prescription, travel, and healthcare system costs. Some adherent patients mentioned that support with the cost of RZV, including private insurance that fully/partially covered RZV (8/11), was an important facilitator to completing the vaccination series as recommended.

A facilitator for most adherent patients was convenient and efficient processes for obtaining and receiving RZV (10/11). One patient from the Prairie Provinces described that their easy and quick vaccination experience facilitated adherence (Table 4).

Receiving reminders in the form of phone calls, face-to-face interactions with HCPs, e-mails, or texts was a common facilitator to RZV completion and adherence (adherent: 10/11; non-adherent: 4/10). Both adherent (7/11) and non-adherent (4/10) patients expressed that reminders from the pharmacy, physician’s office, or pharmaceutical company would have been helpful.

Discussion

This cross-sectional study used a qualitative concept elicitation approach to gather information on HCP and patient knowledge and attitudes toward RZV, as well as the barriers and facilitators to completion of and adherence with the RZV two-dose regimen among adults aged ≥50 years in Canada. HCPs and patients identified similar factors underlying RZV adherence, including out-of-pocket cost, lack of insurance coverage, HCP-provided education and encouragement, forgetfulness/lack of reminders, and inconvenient processes to obtaining RZV. Patients tended to describe individual-level barriers and facilitators, such as self-motivation, side effects, and ease of access. Conversely, HCP responses were more reflective of system-level barriers and facilitators that ultimately affect patients on an individual level, such as provincial vaccination programs, inconsistent RZV stock across clinics, and COVID-19 lockdown measures. Overall, the barriers and facilitators identified from these interviews mirrored those identified from the targeted literature review, but patients in this study provided further details on these factors. For example, patients explained the importance of self-efficacy, in terms of self-motivation and concern for one’s own health, and ease of vaccine access in facilitating vaccine adherence.

Quantitative studies in the United States (US) have similarly suggested that RZV completion and adherence rates may be affected by COVID-19 measures, and by the accessibility and convenience of the different settings (e.g., pharmacies, physicians’ clinics) where RZV can be obtained.^15,21,22 Social factors, such as household income and ethnicity, were consistently reported as predictors of RZV completion in the US, but not explored extensively in this study examining a Canadian population.^15,21–23 To our knowledge, this is the first qualitative study investigating HCP- and patient-perceived barriers and facilitators to RZV completion and adherence, allowing for the identification of factors that were not captured in earlier quantitative studies, such as an increased need for educating patients on RZV and self-motivation. Although this is among the few studies exploring RZV adherence within North America, further studies in other populations and low-/middle-income countries may reveal factors that are unique to other geographies or patient characteristics.

Some barriers to RZV adherence identified in this study were consistent with reasons for HZ vaccine refusal identified by patients in an earlier study, including high costs, lack of HCP recommendations, and fear of vaccines.²⁴ The study further found that patients continued to refuse HZ vaccination, even after receiving education and strong recommendations from HCPs due to other factors (e.g., cost, insurance coverage, perceived lack of need for vaccine),²⁴ suggesting that strategies to overcome barriers to vaccine adherence and refusal should be multifaceted to target the diverse barriers experienced by individual patients.

In this study, a common barrier to RZV adherence was out-of-pocket cost, aligning with existing research where cost was perceived by Canadian physicians as the primary barrier to adherence to human papillomavirus vaccination.²⁵ Cost was also raised by > 50% of non-adherent patients in this study as a barrier, two of whom attributed not obtaining the second dose to cost. Out-of-pocket cost can be a particularly pertinent barrier for older patients on a fixed income and those lacking supplemental private insurance. Reducing the financial burden of RZV, for instance with subsidies, waiving the cost for high-risk populations, expanding private insurance coverage, or implementing public vaccination programs, may thus facilitate adherence. Research from the US has shown that adults are more likely to receive annual influenza vaccinations if they have no out-of-pocket costs or if vaccine costs are fully covered by health insurance.²⁶

Motivation for full protection against HZ and encouragement and education from HCPs were frequently described as affecting RZV adherence in this study. Furthermore, some non-adherent patients were discouraged from series completion after receiving misinformation about RZV or experiencing unpleasant side effects from the first dose. Given that most patients learned about RZV from their HCP and considered HCPs to be the most trustworthy source of information, HCP encouragement and education on the importance of RZV and receiving both doses within the recommended timeframe, potential side effects, and the benefit of preventing HZ via RZV compared with treating HZ, may be important in facilitating RZV adherence. This is consistent with existing research that demonstrated receiving a recommendation, advice, and education from HCPs improves HZ vaccine uptake and adherence.^11,27–29

At the same time, HCP-provided education may represent a barrier if HCPs do not possess accurate and up-to-date knowledge of vaccine recommendations. Two HCPs in this study expressed wanting more information on RZV, and others incorrectly mentioned being immunocompromised or immunosuppression as contraindications, which may have prevented otherwise eligible, at-risk adults from receiving RZV. Providing continued education to HCPs on changing vaccine guidelines is thus important to ensure HCPs do not inadvertently become a barrier to RZV uptake and adherence.

Interviews also identified patient forgetfulness and lack of reminders as barriers to RZV completion. Establishing reminder systems in pharmacies and clinics may therefore improve RZV adherence by prompting more patients to receive the second dose within the recommended timeframe. Indeed, studies conducted among US pharmacies have shown that reminders from pharmacists improve completion rates of HZ vaccinations.^30,31

In the current study, regional factors were listed as potential barriers and facilitators to RZV series completion. Some HCPs pointed out that government programs that provide RZV free to certain high-risk populations may encourage RZV series completion. HCPs also mentioned regional differences in the process to obtain RZV. For example, RZV is available without a prescription or can be prescribed by pharmacists in certain regions,³² which may affect how convenient it is for patients to obtain RZV. Indeed, when describing the pathways by which they obtained RZV, patients noted that multi-step processes and additional fees may hinder adherence, whereas a more streamlined process may facilitate adherence. Simplifying the process for obtaining RZV and improving vaccine access may thus improve adherence. The emphasis on regional factors is consistent with a quantitative study of second dose RZV completion among Canadian adults, which found differences in vaccine completion rates at a regional level and within selected age groups.⁸

Scheduling factors, travel, and prioritization of other vaccines were also identified as potential barriers to RZV adherence. Thus, co-administration of vaccines, including or excluding RZV, should be considered by front-line immunizers to increase adherence to multi-dose schedules. Public Health Agency of Canada guidelines on concurrent vaccine administration states that generally, co-administration of all vaccines for which an individual is eligible at the same visit is safe and effective to increase the likelihood of the individual being fully immunized, especially for those planning to travel or who are unlikely to return for additional doses.³³

Given the timing of this study, interviews captured experiences of patients who received both RZV doses before the COVID-19 pandemic and those for whom the recommended 2-to-6 month timeframe for the second dose fell after implementation of Canada’s pandemic-related lockdown measures. Many HCPs posited that these measures may have hindered RZV adherence by reducing in-person and non-essential healthcare visits. At the same time, HCPs theorized that the pandemic and recent introduction of multi-dose series COVID-19 vaccines may have increased understanding of vaccination among patients, particularly the importance of getting second doses within the recommended timeframe. While it has been suggested that strict COVID-19 vaccination policies have undermined trust in public health and scientific institutions worldwide,³⁴ there is little research on how the pandemic affected perception of non-COVID vaccines. Further investigation exploring the impacts of COVID-19 on adherence to RZV and other multi-dose series vaccines would be insightful.

Limitations

A notable limitation was the challenge of recruiting non-adherent patients, leading to difficulties in reaching the initial sample size target of 40 patients. The study requirement to provide confirmation of vaccination resulted in additional steps and delays before patients could participate in interviews, occasionally leading to drop-offs before interviews could be scheduled. Nevertheless, this ensured that the patient sample comprised individuals who met the inclusion criteria for number and timing of RZV doses. Sufficient non-adherent patients were ultimately recruited by extending the data collection period by five months, adapting the recruitment messaging to focus on non-adherent patients, and partnering with CanAge. Although the patient sample was smaller than originally intended, saturation analysis indicated that the sample sizes were sufficient, and that further data collection would be unlikely to obtain new information from participants.

While purposive sampling is widely used for qualitative research, it may have introduced selection bias into this study. This was minimized by obtaining equal representation across geographic areas; however, the small number of patients included per sociodemographic group may have limited the generalizability of interview results to various subpopulations of Canada. For example, individuals within the same geographic region may experience different challenges to vaccine access and have different vaccine uptake and series completion rates depending on whether they reside in rural or urban settings, or whether they are part of marginalized communities. As social factors (e.g., age, gender, ethnicity, geographic region) have been highlighted as important determinants of HZ vaccine uptake and adherence in several US-based studies,^15–18 further research on how these factors influence perceived barriers and facilitators to HZ vaccine adherence in non-US settings, such as Canada, is warranted.

Although NACI guidance allows HCPs to consider an interval of up to 12 months between doses,⁷ this study considered patients adherent only if they had received their second dose within 2–6 months, as recommended as the optimal interval for individuals aged ≥50 years. According to an existing study, adherence would be expected to be higher if defined as receiving the second dose within 2–12 months.⁸ Nevertheless, facilitators and barriers are not anticipated to be different with the 2-to-6-month interval chosen to define adherence in the current study.

Conclusion

This cross-sectional, qualitative study identified various factors that help or hinder RZV completion and adherence among adults in Canada. Out-of-pocket cost, lack of insurance coverage, and unreliable or confusing information about RZV were commonly identified as barriers to completion of and adherence to the RZV regimen. Meanwhile, encouragement and education from HCPs, more convenient vaccination processes, and reminders comprise the most common facilitators to patients obtaining full HZ protection via RZV series completion.

These results can inform HCPs on how to overcome barriers faced by their patients in completing the RZV regimen, thus helping inform public health decision-making related to RZV and other adult vaccines with multi-dose series. Opportunities for improvement in the completion of and adherence to the RZV regimen include automated reminder systems, HCP-provided education on the benefits, side effects, dosing schedule, and importance of the second dose of RZV, simplified processes to obtain RZV, and reducing its cost burden from provincial health systems, for instance with increased insurance coverage and other subsidies.

Ethics approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (WIRB-Copernicus Group Institutional Review Board [tracking number: 20210320; approval granted 1 March 2021]) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Authors’ contributions

Substantial contributions to study conception and design, analysis, or interpretation of the data: Amnah Awan, Meaghan O’Connor, April Foster, Kimberly Raymond, Iris Gorfinkel, Shelly A McNeil; drafting the article or revising it critically for important intellectual content: Sydney George, Jessica Regan, Amnah Awan, Meaghan O’Connor, April Foster, Kimberly Raymond, Iris Gorfinkel, Shelly A McNeil; final approval of the version of the article to be published: Sydney George, Jessica Regan, Amnah Awan, Meaghan O’Connor, April Foster, Kimberly Raymond, Iris Gorfinkel, Shelly A McNeil.

Acknowledgments

The authors acknowledge Cindy Umanzor-Figueroa and Bonita Basnyat, former employees of Quality Metric Inc., Johnston, RI, United States, for data management and analysis, and Roeland Van Kerckhoven, GSK, Belgium for publication management. The authors also thank Costello Medical for editorial assistance and publication coordination, on behalf of GSK, and acknowledge Ellie Fung, Costello Medical, UK for medical writing and editorial assistance based on authors’ input and direction.

Disclosure statement

Sydney George, Jessica Regan: Employees of GSK; Amnah Awan: Former employee of GSK and current employee of AbbVie; Meaghan O’Connor, April Foster, Kimberly Raymond: Employees of Quality Metric hired by GSK to conduct the study; Iris Gorfinkel: Received funding from over 60 clinical trials from numerous pharmaceutical companies and clinical research organizations, received funding from the National Institute of Health, received educational grants from GSK and Merck, and sat on the GSK Shingrix Advisory Board; Shelly A McNeil: Received grants and personal fees not related to this work from GSK, Merck, Pfizer, and Sanofi.

Data availability statement

The datasets generated and/or analyzed during the current study are not publicly available due to maintaining participant confidentiality in qualitative interview recordings. Interview guides used are available upon request from the corresponding author.

Supplementary data

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2317595.

Additional information

Funding

This study was sponsored by GlaxoSmithKline Biologicals SA [Study identifier: 214093]. Support for third-party writing assistance for this article, provided by Costello Medical, was funded by GSK in accordance with Good Publication Practice (GPP) 2022 guidelines (https://www.ismpp.org/gpp-2022).