We examined the influenza vaccination rate among 1191 Tunisian elderly persons with chronic disease(s) during the 2018–2019 influenza season and factors influencing their intention to receive the vaccine. About one-fifth of participants were vaccinated during the 2018–2019 influenza season, while nearly two-thirds expressed willingness to receive influenza vaccination.
Vaccine uptake among the study population was 19.4%, far below the 75% recommended by the WHO. It is possible that the overall coverage of influenza vaccine uptake among the Tunisian older population (including healthy persons and those with underlying conditions) was lower than the rate found in our study population. In fact, the presence of comorbidities has been identified in several studies as a predictor of influenza vaccination in the elderly [15,16,17,18]. Older persons with chronic medical conditions may be more motivated to receive vaccination because they perceived themselves to be at higher risk for influenza complications [15, 19]. Moreover, health professionals tend to stress the importance of vaccination among this high-risk group [15, 17, 19].
The vaccine coverage estimated in our study was lower than that found among elderly in some member states in the Mediterranean region of the Organization for Economic Co-operation and Development (OECD), including Portugal (60.8%), Spain (50.7%), Italy (52.7%), France (49.7%), and Greece (48.9%) [20]. In contrast, the uptake in Tunisia was higher than that observed in Slovenia (11.8%) and Turkey (7.0%) [20]. Only Korea (82.7%) and Mexico (82.3%), two member states of the OECD, have reached the coverage recommended by the WHO [20]. In Africa, very little data is available regarding influenza vaccine uptake among the elderly, despite the sharp increase in the impact of influenza due to the burden of other diseases such as HIV/AIDS and tuberculosis [21]. A recent study among South African private health insurance scheme members showed that the vaccination uptake in persons older than 65 years was 18.5% [21]. Similarly, vaccine uptake rates reported in previous studies among patients with chronic conditions have varied. In a study conducted among patients with chronic diseases visiting an Italian out-patient clinic, Napolitano et al. found that nearly half of participants were vaccinated against influenza in 2018–2019 [22]. However, Ye et al. and Mohr et al., [23, 24] reported that only 7.8% of diabetic patients in china and less than 30% of patients with chronic pulmonary diseases in Germany received influenza vaccine respectively.
While the vaccination uptake rate was low among our study population, nearly two-thirds of participants expressed willingness to receive the influenza vaccine. Most previous studies examined factors associated with previous influenza vaccine uptake, but this study’s main interest was in the factors associated with willingness in regard to future vaccination. In fact, even if influenza vaccine uptake could be predictive of future uptake, receipt of vaccine may vary from season to season [7, 25,26,27]. According to Zimmerman et al. [28], intention was “the strongest predictor of behavior”, however the environment and the cues for action such as the medical advice are also strong motivators as shown in our study.
We found that willingness to receive influenza vaccine among the elderly was not influenced by socio-demographic factors. Compared to persons with other diseases, people suffering from chronic pulmonary disease and those with diabetes were more willing to be vaccinated, which is consistent with two previous studies that found older persons with pulmonary diseases are more likely to be vaccinated [29, 30]. These groups may have higher perceived severity when they contract the influenza virus, since it is a respiratory infection that could decompensate chronic pulmonary diseases or lead to severe acute respiratory distress when the infected is immunocompromised. There remains a need to improve knowledge about influenza vaccination in the older population and to inform elderly about chronic conditions that can increase the morbidity and mortality tolls of influenza. In agreement with previous studies, persons willing to receive influenza vaccine were more convinced of the danger of influenza for elderly persons and for persons with chronic diseases. They were also significantly more persuaded by the effectiveness of the vaccine, and perceived less its side effects for elderly persons compared to those who refused vaccination [16, 31]. In our study, reasons reported as discouraging the influenza vaccine uptake were, mainly concerns that the vaccine could cause side effects (71.5%) and beliefs of its ineffectiveness (33.9%). These findings, corroborates the conclusions of previous studies [2, 18]. It is important to correct misconceptions about adverse events and efficiency of the vaccine [1]. In fact, influenza vaccines are generally well tolerated and safe among elderly [6] and can even confer cross-protection when the circulating strains are not well matching the vaccine strains [32].
Our study is consistent with previous findings that demonstrated that willingness to be vaccinated was strongly associated with former vaccination status [23, 26, 28, 31, 33,34,35,36]. Indeed, positive experience with the vaccine may lead to perception of higher benefits and fewer barriers to vaccination [36], making those who received the vaccine more likely to be regularly compliant [33, 34]. In fact, once individuals have adopted a behavior, they are likely to change their beliefs to be in agreement with this behavior [37]. Thus, campaigns promoting influenza vaccination among the elderly may have a snowball effect, inducing a cumulative increase in vaccination rates every year [35].
The multivariate analysis showed that trusting the advice of heath care providers was significantly associated with willingness to receive vaccination among elderly persons. We found the main reason for accepting influenza vaccine was receiving a doctor’s recommendation (41.1%) as well. The most trusted sources for information about influenza vaccine were doctors (91.5%), followed by pharmacists (17.6%), and then other healthcare professionals (14.1%). These findings highlighted the important role that physicians could play in improving influenza vaccination uptake among elderly people with chronic disease(s). They are consistent with previous studies showing that recommendations from health care professionals are one of the strongest facilitators for influenza vaccination [1, 16, 23, 34]. Physicians in particular have a crucial role in educating their patients to adopt relevant attitudes and practices toward influenza vaccination [1]. Paradoxically, according to a systematic literature review, several studies reported that many physicians do not recommend the vaccine to their patients [34]. Potential explanations were that doctors cover a wide range of topics during consultations, underestimating the key influence vaccines can play, etc. [34, 35, 38]. A study conducted in Taiwan suggested that physicians give more importance to treatment than to prevention of diseases, and that some doctors may fear further burdening an already weakened immune system in older patients with chronic diseases [35]. This confirms the need to promote the comprehensive approach in the medical practice including, promotion, prevention and restauration of health. Our study advocates for targeting the health care professionals, who should be aware of their crucial role in promoting influenza vaccination among their patients as demonstrated elsewhere [39, 40].
Our study is one of the first on influenza vaccination among elderly with chronic diseases, in Tunisia. Our findings could be of great importance in the current context of COVID-19 pandemic since some factors influencing the attitudes of elderly people towards influenza vaccine could also determine their decisions regarding COVID-19 vaccination which is also recommended for this population group. This study had several limitations. First we did not include those who are seeking care at the university hospitals or in the private sector. These patients might have more severe stages of chronic diseases which might affect the generalizability of our findings, as their knowledge, attitudes, and practices may differ from those in our survey. Second, data about vaccine uptake were self-reported and not validated with medical records; therefore findings might be subject to recall biases [1, 7, 16,17,18, 31]. We believe that the exclusion of persons with even mild cognitive disorders reduces this potential bias. Unfortunately, medical validation of influenza vaccine uptake was not always possible. Third, as many elderly participants were illiterate we did not use a self-administered questionnaire, which may lead to a social desirability bias [33]. Finally, the cross-sectional design of our study did not allow for inferring causal relationships between dependent and independents variables [19, 26].