5.1. Descriptive Statistics
In 2006/2007, 24% of the respondents reported they had been vaccinated against influenza (145 out of 616). Almost 68% of the employees that reported getting vaccinated in 2006/2007 said they had been vaccinated at a worksite program. Others (32%) got the vaccine from their family physician or at their HMO clinic.
summarizes the basic demographic information and characteristics for the sample according to vaccination status in 2006/2007. The table reveals that among the 568 participants (53% men and 47% women), percentage of vaccinated employees in 06/07 was 30% for men and 18% for women (p value < 0.01). In addition, the percentage of vaccinated employees was higher among married versus
unmarried individuals (27% and 15%, respectively, p value < 0.01), and among veteran Israelis versus
new immigrants (arrival after 1990) (p value = 0.02). The table also indicates an increase in vaccination rate with age (p value < 0.01) (49% among those aged 55 and over), an increase as the perceived cost of vaccination decreases (p value < 0.01), and an increase associated with increased perceived self-risk of contracting influenza without being vaccinated (p value < 0.01). Moreover, among the 252 employees offered flu vaccination at work, 39% were vaccinated in 2006/2007, while only 12% of the 310 who were not offered the vaccine at work were vaccinated (p value < 0.01). The percentage of those vaccinated did not differ significantly among those with higher and lower levels of education.
5.2. Main Reasons for Accepting or Rejecting Flu Shots
summarizes the main reasons indicated for accepting (Table 2a
) or rejecting (Table 2b
) the flu shot in 06/07. The results in Table 2
part (a) show that the top motivators for getting a flu-shot in 2006/2007 were: (a) To reduce my chances of contracting influenza (80%); (b) The vaccine was available at my work place (35%); (c) Vaccination was recommended to me (19%); (d) I am accustomed to getting a flu shot each year (19%); (e) I do not want to miss any work because of influenza (19%). Respondents could select more than one reason.
part (b) also shows that the main reasons for the decision not to take the vaccine in 2006/2007 were: (a) There are many strains of influenza (23%); (b) The vaccine is not effective (22%); (c) I do not believe in immunizations (21%); (d) I do not like injections (20%). In addition, it is interesting to note that 16% of the unvaccinated sample mentioned lack of time as one of the reasons for not getting vaccinated. Moreover, some of the reasons for rejecting the vaccine indicate a lack of knowledge about the vaccine among employees, including: “The vaccine is not effective” (22%); “The vaccine is not important” (18%); and “The vaccine can cause influenza” (8%).
5.4. Results for HBM Categories
shows the mean values of the HBM model categories and the category variables (defined in Appendix 1a
) as indices on a 5-point Likert scale (the scale for HBM categories ranged from “strongly agree”-1, to “strongly disagree”-5) measured by vaccination status in 2006/2007 and by intention to be vaccinated. The Cronbach’s alpha coefficients for the HBM categories were: perceived susceptibility (HBM1) −0.654, perceived seriousness (HBM2) −0.628, perceived benefits (HBM3) −0.686, perceived barriers (HBM4) −0.723, and health motivation −0.601.
As expected, the results in Table 4
indicate that for individuals who had been vaccinated in 2006/2007, the levels of the following five categories were significantly lower than these levels for the non-vaccinated group: susceptibility (2.98 vaccinated, 3.2 non-vaccinated); seriousness (1.92 vaccinated, 2.15 non-vaccinated) benefits (2.56 vaccinated, 3.22 non-vaccinated), health motivation (2.56 vaccinated, 2.64 non-vaccinated), and knowledge (3.01 vaccinated, 3.43 non-vaccinated). The barriers category was significantly higher for the vaccinated than for the non-vaccinated group (3.89 and 3.26, respectively). Similar differences in HBM categories were obtained between the group that intends to be vaccinated the next year and the group that does not intend to get a flu shot in the coming year. Therefore, on average vaccinated individuals perceived influenza as a more serious illness than did those who were not vaccinated. In addition, vaccinated individuals felt they were more susceptible to illness, perceived more benefits from vaccination, and had fewer barriers to getting the flu shot than did the non-vaccinated employees. Moreover, on average the vaccinated individuals were more knowledgeable regarding the vaccine and influenza and had higher levels of health motivation. The same conclusions hold for the differences between the group of employees that intended to get the vaccine in the next year and the group that did not intend to do so. In general, these results are compatible with previous studies that referred to health care employees [13
5.5. Results of the Analytical Model
The analytical model examines the effect of each one of the explanatory variables on the dependent variable, controlling for all other variables including the socio-demographic characteristics. Table 5
presents the results of the logistic model regressions. In Table 5
(a), the dependent variable is a dichotomous variable that is equal to one if the individual had a flu shot in 2006/2007 and to zero if not. In Table 5
(b), the dependent variable is a dichotomous variable that is equal to one if an individual said that he/she “definitely intends” or “probably intends” to get a flu shot in the next year, and to zero for “definitely do not intend”, and “probably do not intend”. The analysis of “intention to be vaccinated” was performed among those who did not take the flu shot in 2006/2007, since we found that the vaccination status in 2006/2007 was the strongest predictor of the intention to get the vaccine in 2008 (124 out of 141 subjects vaccinated in 2006/2007 said that they intend to get the flu shot in 2008, versus
only 77 out of 455 that were not vaccinated in 06/07 and said that they intend to take it in 2008 (OR = 35.8 95%, CI = (19.9, 66.6)).
The independent variables in parts (a) and (b) are: age group (less than 41, 41–55, 56 and above), gender, health status, whether or not the vaccine was recommended to the individual, perceived cost of vaccination, whether or not the vaccine was offered at work, perceived infection risk without vaccination (high, medium, low), knowledge about influenza and the vaccine, and HBM categories.
The results in Table 5a
(columns 3–5) show that the significant factors positively
affecting vaccination status in 2006/2007 are: (a) whether the vaccine was offered at workplace: with vaccine offered at workplace increasing the odds of employees getting the vaccine by 5.7; (b) employee age: the odds of an employee aged 56 and up getting vaccinated are three-times higher than for an employee aged less than 41, (c) higher perceived risk of infection without vaccination, (d) HBM3—higher levels of perceived benefits, and (e) HBM4—lower levels of perceived barriers.
The results in Table 5b
(columns 6–8) show that the same significant factors affect the intention to get the vaccine in the next year as those affecting vaccination status in 2006/2007 (except for the age group variable). In addition, we found that higher levels of perceived seriousness of influenza (HBM2) and greater knowledge about the illness and the vaccine increase the odds of intention to get the vaccine.
To test the robustness of the results, we analyzed equations (1)
simultaneously, (meaning a joint analysis for the two dependent variables: the intention to be vaccinated and the status of vaccination in 2006–2007). The results of this analysis, not shown in the paper, indicated that the set of coefficients and significant predictors are very similar to the predictors that we found in the separate equations analysis.
Using additional logistic regression, we also examined the effect of past vaccination (number of vaccinations during the years 2002–2005) on vaccination status (data not shown here). The results indicate that the odds of being vaccinated increase significantly with higher perceived benefits, lower perceived barriers, vaccine offered at workplace, and higher number of vaccination during the years 2002–2005. Yet, we did not find any significant effect of perceived infection risk or of age group on employees’ vaccination status. These results may suggest that past experience with the vaccine dominates other possible reasons for deciding to get vaccinated, including age. People who had a good experience with the vaccine in the past may continue to be vaccinated routinely each year. Our result that past experience with the vaccine affects vaccination status is also compatible with the findings of Sendi et al. (2004).