EXamining the knowledge, Attitudes and experiences of Canadian seniors Towards influenza (the EXACT survey)

Influenza is ranked among the 10 infectious diseases with the highest burden in Ontario [1]. Approximately half of influenza infections are asymptomatic or mild [2] and most who experience “influenza-like illness” (ILI; upper respiratory illness of sufficient severity to affect activities of daily living) will recover within 10 days [3]. However, others, particularly those 65 years of age and older, are at greater risk for a more detrimental impact through secondary medical complications, including pneumonia, cerebrovascular events, as well as exacerbation of underlying medical conditions [4]. Vulnerable older adults can also have persistent functional impairment following an episode of influenza; this “catastrophic disability” has lasting implications for the health and well-being of older adults and their families, and carries substantial resource implications for health systems [5]. As such, it is important to move beyond traditional consideration of influenza as a cause of short-term morbidity and mortality, to appreciate influenza’s health impact over longer time horizons.

In Canada, each province is responsible for developing its own immunization programs. Although the exact date of program initiation varies by year and by jurisdiction across the country, each province publicly funds the influenza vaccine for those 65 years and over, and most have done so for nearly two decades [6, 7]. The influenza vaccine is typically available in all provinces beginning in early-middle October, and residents can be vaccinated at any time before the end of the season but are encouraged to receive the vaccine as early as possible; the majority of individuals who opt to be vaccinated receive the vaccine by the end of December [8]. To protect the health of older adults, Canada’s National Advisory Committee on Immunization (NACI) has set a national target immunization rate of 80% [9] and yet vaccine uptake in seniors remains sub-optimal at 64–67% [10]. This is likely partially due to vaccine hesitancy created by reports that vaccine effectiveness (VE) is lower in older adults compared to younger populations [11‐15]. However, this variability in VE is a source of debate [12] with recent research demonstrating that VE might also be significantly confounded by frailty, a measure of vulnerability to adverse health outcomes based on accumulation of health, mobility and functional deficits [16].

It is currently unknown whether Canada’s senior population is aware of the potential short- and long-term impacts of influenza, and if/how this affects their decision to receive the seasonal influenza vaccine. We therefore aimed to explore older Canadians’ experience of and views on influenza vaccination and illness through a survey of Canadian seniors. Understanding the impact of influenza on the health of older adults, as well as how the knowledge of this impact is linked to vaccination decision-making, could inform the development of more targeted tools and interventions to optimize vaccine uptake. Specifically, our objectives were to i) understand older adults’ self-reported experience with influenza, including increases in frailty and exacerbations of chronic conditions; and ii) evaluate knowledge, attitudes and behaviours towards influenza and influenza vaccines.

Between March 20th and April 5th, 2017, completed surveys were collected from 5014 people 65 years and older, with representation from all ten Canadian provinces (Table 1). The mean age of the respondents was 71.3 ± 5.17 years (range = 65–96), 50% were male, 42.6% had one or more chronic conditions, and 9.6% considered themselves vulnerable or frail. The median time to complete the survey was 14 min. Overall response rate was 30.4%.

In our survey of 5014 Canadian seniors, two-thirds reported having been vaccinated with last season’s influenza vaccine although many were unaware that they are at risk for influenza-related complications, and held misperceptions about influenza vaccines. One in five respondents reported that they had influenza or ILI in the 2016/17 season; among those individuals, more than 40% took over 2 weeks to recover and 13.9% were hospitalized. While our sample was relatively fit and healthy at baseline, individuals who had influenza/ILI reported declines in function and worsening frailty during their acute illness phase, and for 3.1%, this persisted after “recovery”. Older age, significant trouble with memory, and having influenza/ILI were among the independent predictors of declines in health and function.

We recruited a large sample, with respondents from across Canada. The immunization rate observed in this study (67.9%) is similar to a recently reported rate of 64% [26], lending support to our sample’s representativeness. We observed that having had influenza/ILI this past season was significantly associated with lasting frailty and functional impairment, and that respondents reported high healthcare utilization, seeking influenza care and treatment at pharmacies, family physicians’ offices, ER departments, and even as in-patients. Most reported that worsening function and frailty were confined to the period of influenza illness/ILI. However, this temporary loss of independence is not inconsequential; the inability to do routine daily tasks translates to an increased need for assistance, which is burdensome for older adults who live alone or are themselves caregivers. Future work is required to further investigate the associations that we have identified, in order to establish whether it is truly a causal relationship between the influenza illness and the impaired frailty and function, or whether these could be attributable to confounding factors that lead those afflicted to more often experience these declines. Additionally, examining the long-term impact of influenza in a frailer group of seniors would help determine whether our observations are simply “the tip of the iceberg”. The literature suggests that a substantial subset of frail older adults emerge from an acute illness such as influenza with persistently worse function than prior to illness [5, 27]. We also found that significant memory troubles and several chronic conditions were important independent predictors of persistently worse frailty and function following the influenza season, highlighting the vulnerability of older people with these conditions to health declines and the need for interventions targeting those most at risk for influenza-related complications.

Most respondents indicated that they opted for the influenza vaccine because their HCP recommended it, which supports previous findings [28]. Similar to past studies, we observed that the most common reasons for not receiving the influenza vaccine were not believing that influenza was severe or that the vaccine was effective [28‐30]. Our study demonstrates that seniors hold misconceptions regarding influenza and influenza vaccine, particularly those who do not typically opt for annual influenza vaccination. This corroborates previous studies finding that adults who recognized influenza’s severity and perceived themselves as “high-risk” were more likely to accept the vaccine [31]. This may also be linked to psychological factors – a German study showed that feeling high levels of stress is positively associated with opting for influenza vaccination [32]; it is possible that believing oneself to be at greater risk for influenza-related complications leads to significant stress. There are evident knowledge gaps preventing individuals from making optimal vaccine-related decisions. These gaps will gain in importance over time –our survey sample is an aging cohort who may become tomorrow’s frail older adults. Future work is needed to increase education, promote awareness and combat myths of the clinical consequences of influenza in the senior population and the risk/benefit profile of influenza vaccines.

Our study had limitations. Our response rate of 30.4% is fairly standard for online surveys, but it is possible that those who responded may have different health experiences from those who did not. To understand the impact of this potential bias, we have compared our findings to the literature, where possible, and have noted strong similarities, lending credibility to our results. Our sampling frame is unlikely to have included very frail Canadians, or those who suffered long-term consequences of influenza resulting in hospitalization or residing in long-term care facilities (LTCF) at the time of survey completion. However, given that only 4% of Canadians reside in LTCF [33], we expect that this exclusion had minimal effect on our estimation of the overall impact of influenza in seniors. Further studies are needed to focus on these populations. Our online panel sample may have over-represented cognitively-well older adults. Our survey may also have appealed to people with strong views on vaccination or desire to share illness experiences. However, we did have responses from all Canadian provinces, with a wide age range (24.2% aged 75+) and gender parity. No data on the survey non-responders were collected, and therefore it is not possible to state whether we were able to completely eliminate potential non-response bias. However, we implemented several measures including pilot-testing the survey with 10 older adults and having the survey open for 3 weeks, to ensure that the survey was easy to understand and to facilitate participation. Since the survey took place just after the season, there is potential for recall bias. Additionally, respondents may have had ILI caused by other respiratory viruses, overestimating the incidence of influenza and also affect the data around clinical impact. To limit this effect, we asked whether the respondent had a clinical diagnosis, and provided a restrictive set of criteria for ILI. Our reported influenza rate of 4.9% is similar to laboratory-confirmed influenza rates previously observed in senior populations [34, 35], while our ILI rate of 16.6% corroborates previous findings [36]. Finally, our survey is subject to the same type of biases as others using a self-report design. We aimed to minimize the probability of a recall bias with the relatively short period between the events and their assessment, and the wording of the questions which was designed to cue recall of reportable events. We were unable to confirm patient responses through chart audits, so recall bias and issues with cognitive impairment remain a possibility. However, previous studies which have compared the reports of seniors to their medical charts have found seniors to have reliable memories, particularly for events which required a visit to a healthcare provider [37].

Our results show that while a majority of older adults receive the yearly seasonal influenza vaccine, coverage rates and knowledge about influenza illness and vaccine remain suboptimal. Those with influenza/ILI reported functional declines and worsening frailty during their illness, and some have not fully recovered. Further research is required to assess this association. It is important to ensure that Canadian seniors (along with clinicians and policy-makers) have accurate information to make vaccine-related recommendations which would facilitate increased vaccine uptake and consequently optimize the health protection of this high-risk population. This includes the understanding that recovery from influenza can be prolonged, incomplete, and increase the burden on patients and caregivers. Given that frailty and function are closely linked to older adults’ wellbeing and independence, it is critical to consider influenza’s impact on these health outcomes when designing future research studies and public health programs for influenza prevention.