Motivators and barriers to vaccination of health professionals against seasonal influenza in primary healthcare

In the cross-sectional study below, the data for analysis was gathered with an anonymous questionnaire for the 2014/15 vaccination season, from April to June 2015.

We invited all major healthcare providers in primary care in the region, among them primary healthcare centres with associated emergency services, nursing homes and private contractors. The list of health professionals was obtained via the National Institute for Public Health’s (NIJZ) freely accessible database of primary health professionals and covered the following positions: physicians, dentists, practice and registered nurses, community nurses, paramedics, nurse-carers, physiotherapists and occupational therapists.

The vaccination rate in 2014/15 was compared to the rate in 2013/14. We calculated the number of the vaccinated health workers in 2013/2014 from the database of the NIJZ (the number of all health workers [16] in the region and the number of vaccinated health workers in the region in 2013/14 [17].

The anonymous questionnaire made up of 27 questions and divided into 5 sections was designed based on both the review of specialised literature and the overall aim of the study. We have designed the questions on the basis of domestic and international literature [9‐12] and national “grey” literature – specialist thesis that also involved qualitative research (semistructured interviews) with chronic patients and their attitudes towards vaccination against flu. The sections covered the demographic data of the participants, questions about health characteristics, knowledge and beliefs of influenza vaccination, and the reasons pro or against being vaccinated (multiple choice questions).

The outcome variable was vaccination against influenza in the season 2014/15. Several explanatory variables about potential reasons for and against vaccination were tested for associations with the vaccination. The multivariable logistic regression model included demographic characteristics (gender, age over 50 years, occupation of health professional), health characteristic (self reported presence of chronic disease), free vaccination availability, being well informed about the influenza (self assessed knowledge), beliefs about exposure at the work place, safety and effectiveness of the vaccine..

The data was processed with the IBM SPSS 22 (IBM Corp., Armonk, NY) software. The statistical analysis included descriptive statistics, which was presented by frequencies and percentages or by mean values ± standard deviations. Binary logistic regression using the standard entry method was apllied to determine the associations between the explanatory variables discussed and influenza vaccination. Crude and adjusted odds ratios with 95% confidence intervals were calculated. The explanatory variables included in the multivariable regression model were adjusted among each other. The explanatory variables included in the multivariable regression model were also tested for multicollinearity using variance inflation factor (VIF) [VIF = 1/(1-R²)]. R² (Nagelkerke R² for logistic regression) was obtained by regressing each explanatory variable on the remaining explanatory variables in the model. Statistical significance was set at p < 0.05.

Four hundred and eighty nine primary health professionals from the national list of healthcare professionals in the Koroška region were invited to participate in the study. Three hundred and thirty four healthcare professionals agreed to participate. The questionnaire, delivered in paper form, was completed by 263 health professionals (53.7%), while 13 were excluded from the analysis due to incomplete data. The final sample size therefore amounted to 250 health professionals (51.1% of the eligible sample and 74.8% of the distributed questionnaires). The basic characteristics of participants are listed in Table 1.

The mean age of health professionals was 41.5 ± 12.2 in the range of 19 to 74 years. Among physicians, family and general practitioners were dominant (37 out of 44 or 84.1%); 10 out of 37 general practitioners (27.0%) were vaccinated.

In the 2014/15 vaccination season, 30 people or 12.0% of health professionals in our sample were vaccinated which is 5% less than the year before. As the data on vaccination of primary care workers was not available, we could compare the vaccination rate in 2013/14 of all health workers in the region from the national database of vaccination. Out of 1113 health workers, 192 people or 17.3% of health professionals were vaccinated in the 2013/14 vaccination season [17]. The difference was statistically significant (chi² = 4.121; p = 0.042).

The reasons for vaccination are shown in Table 2. The two most important reasons for vaccination, expressed by health professionals, were belonging to a risk occupational group (83.3%) and self-protection against influenza (70.0%).

In the 2014/15 season, 220 (88.0%) health professionals did not vaccinate against seasonal influenza. The reasons for the decision against vaccination are presented in Table 3. The two most important reasons against vaccination were not being directly occupationally exposed (37.3%) and doubting the effectiveness of the vaccine (37.3%).

Table 4 presents the results of logistic regression of the factors associated with influenza vaccination. Age above 50 years (OR = 3.73, 95%CI = 1.27–10.97, p = 0.017) and belief that the vaccine is effective in prevention of influenza (OR = 12.38, 95%CI = 4.06 –38.30, p < 0.001) were positively associated with influenza vaccination. Nurse occupation (OR = 0.24, 95%CI = 0.08–0.75, p = 0.014) was negatively associated with influenza vaccination in comparison to physicians. Included variables in the multiple logistic regression model explained 51.6% of the variance of the dependent variable (Nagelkerke R² = 0.516). Regarding multicollinearity the maximum VIF among explanatory variables was 1.57, which was substantially below the rule-of-thumb cutoff of 4 [18], so there were no issues with multicollinearity.

In comparison to studies in other countries [9‐11, 23, 24] where the most frequent reasons for vaccination were self-protection and free and easy access to vaccines, this study showed similar findings. The greatest motivator for vaccination of health professionals was the awareness that they are in the risk group for infection (83% of vaccinated respondents reported it). It was followed by the tendency for self-protection (70%), which was statistically not significantly behind, as it is essentially very similar and the protection of family members and co-workers (60%). Despite the fact that vaccination of health professionals is highly recommended, also for the indirect protection of patients, this was clearly a lesser factor (46.7%) in their choice to vaccinate.

In the bivariate analysis of factors associated with vaccination, the presence of a chronic illness, older age, being informed about influenza, belief in vaccine effectiveness and free vaccinations for employees were all significant, partly similar to Sočan et al., who showed that the factors associated with the decision to vaccinate are older age, being a hospital employee, being a vaccinator and having a chronic illness [12].

The multiple logistic regression model showed that the decision to vaccinate is influenced by age above 50 years, similar to other studies [25] and the respondents’ belief that the vaccination is effective. Interestingly, in our model, trust in professional recommendations and public health or lack of professional information to vaccinate was not important to our participants, although they were important factors for vaccination in the systematic review of Prematunge [26].

So-called hesitancy to vaccination [27] has been in the centre of research interest in the last years. This study shows that in the 2014/15 season, 220 health professionals (88.0%) were not vaccinated. The most common reasons against vaccination were listed in two groups: health professionals do not feel the need for vaccination (37.7%) and have a negative attitude toward vaccination, either from a first-hand bad experience (30.5%) or doubt in the vaccination’s effectiveness (37.3). Similar results were reported by foreign studies [9‐11, 20]. This specific influenza hesitancy needs special investigation for further explanation. In the Schmid systematic review, lack of confidence in vaccine and vaccination was found to be the most important barrier for healthcare professionals [27].

Lack of information or insufficient awareness was mentioned by other studies as one of the most important reasons for refusing vaccination [9‐11]. According to the respondents of this study, this did not impact the decision to vaccinate, as only 3.6% of health professionals mentioned it and statistically, it was significantly lagging behind the two primary reasons. In expert debates on mandatory vaccination for health professionals, however, it was emphasized that the decision depends on scientific evidence proving the effectiveness of the vaccine, its benefits, and its burdens and risks [28].

In this study, another important factor associated with the refusal to vaccinate turned out to be the respondents’ occupation. The multiple logistic regression model showed a negative association with the profession of nurse. Our study does not present an answer explaining the causes. In the literature, however, we found studies that specifically investigate answers to this issue. In Switzerland, a qualitative study was conducted among nurses from two different hospitals. The interviews showed that they value and maintain a healthy life-style. They do not believe that influenza vaccinations are beneficial; on the contrary, they consider them to be harmful (falling ill post-vaccination). They are afraid of the side effects and they have doubts in the vaccine’s effectiveness. Amongst their reasons not to vaccinate was also the wish for autonomous decision-making about one’s body and health, and distrust in the environment and scientific study findings [29].

All primary health professionals of the Koroška region were invited to participate in the study, but we could only include the institutions and private contractors that agreed to participate. Hence, the sample was not representative. This affects the generalizability of the results although the response rate among the participants was good (74.8%). The limitation of the study was also the fact that it focused on a single region in Slovenia, which is why the subgroups of health professionals were small and the generalization of the results for the entire population of health professionals in Slovenia is not possible. It was also not possible to analyse motivators and barriers according to the specific professional groups or to find any differences among them. Further on, the cross sectional design of the study did not allow any causal relationship to be established between the variables. Finally, as to our knowledge there are no validated questionnaires on this topic, the questionnaire we used was designed according to the literature review, aims of the study and previous qualitative data which limits the comparison of factors associated with influenza vaccination to other studies.