In Spain, influenza vaccination is available in companies free of charge for their workers. Despite this, vaccination coverage against influenza is very low in these groups.
ObjectivesThe aim of this work is to know the reasons for acceptance of influenza vaccination in a working population.
MethodsDuring the 2021–2022 influenza vaccination campaign, we conducted a survey of two groups of workers at the automobile factories of RENAULT ESPAÑA S.A. in the cities of Valladolid and Palencia (Spain). The first group (NV) was formed by 304 (33.5%) workers who did not receive the influenza vaccine in the previous season. The second (V) was formed by 604 workers (66.5%) who had been vaccinated against influenza at least the previous season. In the NV group, they were asked the reasons why they did not get vaccinated the previous season and if they did so in 2021–2022. In group V, only the reasons for continuing to be vaccinated were asked.
ResultsIn NV, the main reason for avoiding vaccination in the previous season was the lack of perception of the severity of the influenza infection (74.7%), and 31.6% and 29.0% of them decided to get vaccinated during the 2021–2022 season due to the fear of co-infection of SARS-CoV-2 and influenza and medical recommendations respectively. The 83.5% of group V responded that the reason for getting vaccinated in 2021–2022 was their adherence to vaccination.
ConclusionsThe results show that medical recommendation is the best tool to vaccinate workers against influenza and make them adhere to it. Also, the fear to co-infection of COVID-19 and flu was a frequent reason for getting vaccinated, above all in NV.
En España la vacunación antigripal está disponible en las empresas de manera gratuita para sus trabajadores. A pesar de esto, las coberturas vacunales frente a la gripe son muy bajas en estos grupos.
ObjetivosEl objetivo es conocer los motivos de aceptación de la vacunación antigripal en la población trabajadora.
MétodosDurante la campaña de vacunación de gripe 2021–2022 realizamos una encuesta a dos grupos de trabajadores de las factorías automovilísticas de RENAULT ESPAÑA S.A. en las ciudades de Valladolid y Palencia. El primer grupo (NV) estuvo formado por 304 (33,5%) trabajadores que no recibieron la vacuna antigripal la temporada anterior. El segundo (V) estaba formado por 604 trabajadores (66,5%) que habían sido vacunados contra la gripe al menos la temporada anterior. En el grupo NV se les preguntó las razones de porque no se vacunaron la temporada anterior y si lo hicieron en 2021–2022. En el grupo V se preguntó únicamente las razones para seguirse vacunando.
ResultadosEn NV, la principal razón para evitar la vacunación en la temporada anterior fue la falta de percepción de la gravedad de la gripe (74,7%), y el 31,6% y 29,0% de ellos decidió vacunarse durante la temporada 2021–2022 por el miedo a la co-infección del SARS-Cov-2 y gripe y a las recomendaciones médicas respectivamente. El 83,5% del grupo V respondió que el motivo de vacunarse en el 2021–2022 fue su adherencia a la vacunación.
ConclusionesLos resultados muestran que la recomendación médica es la mejor herramienta para vacunar frente a la gripe a los trabajadores y hacerles adherentes a la misma. También, el miedo a la co-infección de COVID-19 y gripe fue una de las razones más frecuentes para vacunarse, sobre todo en NV.
Influenza causes worldwide one billion cases, 3–5 million hospitalizations and over 290,000–650,000 deaths each year.1 Vaccination is the best way to prevent this disease2 but, in recent years, a decrease in coverage was observed in different risk groups such as elderly or people with underlying diseases.3 In addition, influenza vaccination has especially low acceptance among groups without specific recommendation, such as healthy adults.4 For example, in the US the influenza vaccine coverage in adults is nearly 50%, that is far from the Healthy People 2030 target of 70%.5 However, there are great differences among countries regarding this coverage. For example, in Spain, one work pointed that the estimated coverage rate of influenza vaccination in adults in 2018–2019 campaign was nearly 11%.6 Other works performed in working-age population show that, in Japan, the influenza vaccine coverage was 24.2–27.6% in 2011,7 was this work was not specifically performed in workers. We did not find any work evaluating vaccine coverage rates specifically in non-health workers.
In Spain, the Ministry of Health recommends influenza vaccination for classic risk groups, such as ≥65 years, people with previous pathologies (children and adults) and health workers.8 However, industrial companies offer free influenza vaccination every year to their workers, so these adults can also access easily to this immunization. Although vaccination is free and voluntary, the rates in these companies are usually low. In Spain, the workforce account for approximately 20% of the population, so they can be a clear target beneficiary for influenza vaccination, which in parallel help protect their cohabitants. In fact, there are some works that describe how influenza vaccination in the working-age population could decrease the influenza epidemic,9 and also how could save absenteeism costs.10
The aim of this study is to know what are the main reasons to accept or to refuse the influenza vaccination in workers that are adherent to flu vaccination is and in others that had never been vaccinated.
Materials and methodsA cross-sectional study was conducted in two automobile production plants of the RENAULT ESPAÑA S.A. group in Spain (Valladolid and Palencia) in the months of October–December of 2021. A survey was performed by the medical staff of the factory to the workers who received the influenza vaccination during 2021–2022 campaign. This survey was conducted in the context of a serological analysis for influenza and COVID-19 only in those people that will get vaccinated against flu. After the worker accepted to participate in the study and signed the informed consent, the medical staff administered the influenza vaccine and also ask for the questions designed for the survey. The survey consisted in different questions about their reasons for accepting the 2021–2022 influenza vaccination, and also the reasons for refusing previous influenza vaccinations. Additionally, the medical staff ask the workers for their age, sex and presence of comorbidities (without specifying the type).
For this work, the recruitment was conducted including the maximum number of workers of the factory that want to be vaccinated against influenza in the 2021–2022 season. First of all, we did a screening to know the interest of all workers to be vaccinated in the present season. Then, the group that accepted being vaccinated was classified in two different subgroups related to their previous vaccine status. One group was formed by workers that had not been vaccinated against influenza the previous season (2020–2021) (NV), and the other was formed by workers that were vaccinated against influenza at least in the previous season (V)(Fig. 1). This work was approved by the Ethics Committee of the Eastern Health Area of Valladolid (Cod: PI 21–2442). All participants signed a written informed consent prior to obtain the survey information. Also, this research was carried out according to the Declaration of Helsinki.
Prior to conduct the survey, the answers were limited for the feasibility of the study. The survey consisted in two different questions. First, we ask both NV and V about the reasons why they had chosen to be vaccinated during the 2021–2022 season, being able to choose between one of the following five options: 1, Because I do it every year (Adherent to vaccination; only for those who were vaccinated in the previous year); 2, Because of the fear of the co-infection of influenza and COVID-19 at the same time (Perception of fear for the emergence of a new disease); 3, Because a physician had recommended to me (active medical recommendation); 4, Because I belong to a risk group or I live with someone at risk (Perception of own or other's need); 5, because you are going to measure my antibodies (Opportunism due to antibodies test).
Additionally, those NV were then asked about the reasons for not being vaccinated the previous season, being able to choose one of the following four options: 1, I was not properly informed about influenza (Lack of information about influenza); 2, I don't feel danger of the flu/I don't need the vaccine (Lack of perceived severity/burden of influenza disease); 3, I am afraid of needles (fear of the vaccination/shot); 4, I am afraid of side effects (fear of side effects of vaccination).
The analysis of the data was focused on a descriptive study of the variables included in the survey in both groups included in the study, and also regarding different demographic and health parameters, such as age, sex and presence of comorbidities of the workers. We use the χ2 to analyze the differences in the proportion of the responses among the different parameters analyzed. Statistical significance was fixed on p < 0.05. For the analysis the SPSSV27 (IBM, Armonk, NY, United States) software was used.
ResultsWe included a total of 908 workers out of the 8043 that both factories have. This means that the factory had a 11.3% of influenza vaccine coverage during 2021–2022 influenza campaign. Of them, 304 (33.5%) had never received the influenza vaccine (NV group) (73.7% males; mean age [CI95%], 41.8 [40.9–42.6]) and 604 (66.5%) were vaccinated at least the previous season (2020–2021) (V group) (74.7% males; mean age [CI95%], 44.0 [43.4–44.6]) (Table 1). A total of 153 workers (25.3%) had at least one comorbidity in the V group and 58 (19.1%) in the NV group.
Demographic and clinical characteristics of the workers included in the study.⁎
| Vaccinated PS* (n = 604) | Non-Vaccinated PS* (n = 304) | Total | ||||
|---|---|---|---|---|---|---|
| Parameter | N | % | N | % | N | % |
| Age group | ||||||
| 18–35 years | 66 | 10.9 | 57 | 18.8 | 123 | 13.5 |
| 36–45 years | 318 | 52.6 | 156 | 51.3 | 474 | 52.2 |
| 46–65 years | 220 | 36.5 | 91 | 29.9 | 311 | 34.3 |
| Sex | ||||||
| Male | 451 | 74.7 | 224 | 73.7 | 675 | 74.3 |
| Female | 153 | 25.3 | 80 | 26.3 | 233 | 25.7 |
| Comorbidities | ||||||
| Yes | 153 | 25.3 | 58 | 19.1 | 211 | 23.2 |
| No | 451 | 74.7 | 246 | 80.9 | 697 | 76.8 |
After asking the first question, “Why did you get vaccinated in the 2021-2022 season?”, the global percentage of answers were different in both groups surveyed. For NV, the most frequent response was the fear of co-infection with influenza and SARS-CoV-2 at the same time, and the implications in terms of severity that this could have (31.6%). Very similar was the percentage observed in those who responded that they were vaccinated based on active medical recommendation by the medical staff (29.0%) (Table 2). The opportunity to know their serological status against influenza and COVID-19 was the reason for receiving the vaccine in 23.7% of those surveyed. In the case of V group, the vast majority chose to be vaccinated again due to adherence to this practice (83.5%), while the rest of the reasons were infrequent (less than 4%), with the exception of the active medical recommendation by the medical staff (7.3%).
Absolut numbers and percentages related to each category of the responses to the first question in V and NV groups regarding age group, sex and presence of comorbidities.
| A1. Adherent to vaccination | A2. Fear to co-infection SARS-CoV-2/Influenza | A3. Active medical recommendation | A4. Own need or someone else's (risk group) | A5. Opportunism (Antibodies test) | A6. DK/NO | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Parameter | V - N(%) | NV - N(%) | V - N(%) | NV - N(%) | V - N(%) | NV - N(%) | V - N(%) | NV - N(%) | V - N(%) | NV - N(%) | V - N(%) | NV - N(%) |
| Age group | ||||||||||||
| 18–35 years | 57 (86.4) | 0 (0) | 0 (0) | 16 (28.1) | 4 (6.1) | 15 (26.3) | 4 (6.1) | 8 (14.0) | 1 (1.5) | 16 (28.1) | 0 (0) | 2 (3.5) |
| 36–45 years | 264 (83.0) | 0 (0) | 12 (3.8) | 47 (30.1) | 25 (7.9) | 45 (28.9) | 11 (3.5) | 14 (9.0) | 6 (1.9) | 37 (23.7) | 0 (0) | 13 (8.3) |
| 46–65 years | 184 (83.6) | 0 (0) | 7 (3.2) | 33 (36.3) | 15 (6.8) | 28 (30.8) | 9 (4.1) | 8 (8.9) | 5 (2.3) | 19 (20.9) | 0 (0) | 3 (3.3) |
| p-value (χ2) | 0.7999 | N/A | 0.6411 | 0.4963 | 0.8294 | 0.8438 | 0.6120 | 0.5037 | 0.9120 | 0.6056 | N/A | 0.1872 |
| Sex | ||||||||||||
| Male | 375 (83.2) | 0 (0) | 16 (3.6) | 69 (30.8) | 31 (6.9) | 67 (29.9) | 19 (4.2) | 25 (11.2) | 10 (1.3) | 50 (22.3) | 0 (0) | 13 (5.8) |
| Female | 130 (85.0) | 0 (0) | 3 (2.0) | 27 (33.8) | 13 (8.5) | 21 (26.3) | 5 (3.3) | 5 (6.3) | 2 (1.3) | 22 (27.5) | 0 (0) | 5 (6.3) |
| p-value (χ2) | 0.5994 | N/A | 0.3311 | 0.6264 | 0.5044 | 0.5354 | 0.6051 | 0.2061 | 0.4857 | 0.3496 | N/A | 0.8845 |
| Comorbidities | ||||||||||||
| Yes | 94 (61.4) | 0 (0) | 2 (1.3) | 11 (19.0) | 10 (6.5) | 5 (8.6) | 11 (7.2) | 7 (12.1) | 2 (1.3) | 7 (12.1) | 0 (0) | 5 (8.6) |
| No | 411 (91.1) | 0 (0) | 17 (3.8) | 85 (34.6) | 34 (7.5) | 83 (33.7) | 13 (2.3) | 23 (9.3) | 10 (2.2) | 65 (26.4) | 0 (0) | 13 (5.3) |
| p-value (χ2) | <0.0001 | N/A | 0.1316 | 0.0216 | 0.6800 | 0.0001 | 0.0184 | 0.5321 | 0.4857 | 0.0207 | N/A | 0.3328 |
| Total | 505 (83.5) | 0 (0) | 19 (3.1) | 96 (31.6) | 44 (7.3) | 88 (29.0) | 24 (4.0) | 30 (9.9) | 12 (2.0) | 72 (23.6) | 0 (0) | 18 (5.9) |
A, Answer; V, Vaccinated the previous year; NV, Non-vaccinated the previous year; DK/NO, Don't Know/No opinion
After that, we described the responses to this question segregated by age group, sex and presence of comorbidities (Table 2). In the case of the V group, the majority of people of each age group responded that they were adherent to vaccination, and similar values were found among both sexes. We found a significant proportion of people with no comorbidities that were vaccinated because they were adherent to vaccination compared to those that present comorbidities (p < 0.0001). On the other hand, the people with comorbidities responded significantly more frequent that they were vaccinated because they need the vaccine because they pertain to a risk group (p < 0.05).
In the case of the NV group, all the age groups responded in a similar proportion to each of the three most frequent answers “Fear to co-infection of SARS-CoV-2/Influenza”, “Active medical recommendation” and “Opportunism”. On the other hand, we found a significant proportion of people with no comorbidities that responded that they were vaccinated because of the three most frequent responses related before than the people that have comorbidities.
After conducting the second question to NV group “Why were you not get vaccinated in the 2020-2021 season?”, the most frequent response was the lack of perception of the severity/burden of influenza disease (74.7%), followed by the lack of information about this disease (10.2%). Fear about the shot (needles) was the option that the lowest percentage of people defended (2.0%). Also, we described the responses to this question segregated by age group, sex and presence of comorbidities (Table 3). The most frequent reason to avoid vaccination in all age groups was also the lack of perception of severity/burden of influenza disease. These figures were also similar regarding the sex and the presence of comorbidities. We did not find significant differences among the age groups in the proportion of the different answers presented in the study. However, we found that women answer significantly more frequent that they were not previously vaccinated due to the fear to side effects of vaccination (p < 0.01). Also, the people without comorbidities responded significantly more frequent that they were not vaccinated due to the lack of perception of severity/burden of influenza disease (p < 0.0001).
Absolut numbers and percentages related to each category of the responses to the second question in the NV group regarding age group, sex and presence of comorbidities.
| A1. Lack of information about influenza | A2. Lack of perceived severity/burden of influenza disease | A3. Fear of vaccination/shot | A4. Fear of side effects of vaccination | A5. DK/NO | ||
|---|---|---|---|---|---|---|
| Parameter | NV - N(%) | NV - N(%) | NV - N(%) | NV - N(%) | NV - N(%) | |
| Age group | ||||||
| 18–35 years | 10 (17.5) | 42 (73.7) | 1 (1.8) | 2 (3.5) | 2 (3.5) | |
| 36–45 years | 12 (7.7) | 122 (78.2) | 4 (2.6) | 10 (6.4) | 8 (5.1) | |
| 46–65 years | 9 (9.9) | 63 (69.2) | 1 (1.1) | 11 (12.1) | 7 (7.7) | |
| p-value (χ2) | 0.1087 | 0.2888 | 0.7206 | 0.1312 | 0.5240 | |
| Sex | ||||||
| Male | 24 (10.7) | 172 (76.8) | 5 (2.2) | 11 (4.9) | 12 (5.4) | |
| Female | 7 (8.8) | 55 (68.8) | 1 (1.3) | 12 (15.0) | 5 (6.3) | |
| p-value (χ2) | 0.6182 | 0.1560 | 0.5877 | 0.0033 | 0.7654 | |
| Sex | ||||||
| Yes | 2 (3.5) | 26 (44.8) | 0 (0) | 4 (6.9) | 4 (6.9) | |
| No | 29 (11.8) | 201 (81.7) | 6 (2.4) | 19 (7.7) | 13 (5.3) | |
| p-value (χ2) | 0.0590 | <0.0001 | 0.7440 | 0.8303 | 0.6307 | |
| Total | 31 (10.2) | 227 (74.7) | 6 (2.0) | 23 (7.6) | 17 (5.6) | |
A, Answer; DK/NO, Don't Know/No opinion
The results of this survey showed that the main reason for not getting vaccinated in the adult worker population was the lack of perception of the risk that the influenza disease can have. Despite the annual data of the burden of disease, mortality and hospitalization caused by influenza,1,11 more than 70% of workers that were not previously vaccinated did not do it because they did not previously know this data. This shows that awareness of this infectious disease is very weak despite the existence of easily accessible vaccination programs in companies, among other places. Some authors have pointed that one of the main reasons for not accepting influenza vaccination is the lack of vaccine recommendation from the physicians.12 In other work performed in working population in Japan, the main reasons for not getting flu vaccination were “Not time to visit the medical institution of the company” and “Unlike to become infected with influenza”.7 On the other hand, it is probably not surprising that this lack of perceived importance about flu as a reason for not being vaccinated is more frequent in people without comorbidities, as the people at risk is probably more committed with their health.
Note that, during our study, only 11.3% of the workforce was vaccinated. This coverage was in line with the data described by other researchers for the adult population of Spain.6 This data show that it is still so much to be done to achieve optimal vaccination coverage that is useful at the collective level. However, in many European countries, influenza vaccination is not universally recommended, so this can be one of the main reasons of the differences among Spain and US in adult influenza vaccine coverage.5
The lack of information about the flu was the second most frequent response, which may well be related to the lack of perception of the severity of this disease. But in Spain the flu caused a total of 27,700 hospitalizations with confirmed influenza infection in the 2019–2020 season, 1800 cases that required admission to the ICU and a total of 3900 deaths (data from the Influenza Surveillance System in Spain).13 These data show that it is a problem for Public Health, and also a recurring one, that does not miss the meeting every year. Our data also show that, for working women, the fear to side effects is an important reason to avoid influenza vaccination, more than men.
The three most frequent reasons for getting vaccinated in NV during 2021–2022 season were the coexistence of influenza and COVID-19 at the same time (fear that its concomitance will result in more severe cases), the active medical recommendation and the opportunity to know their serological status, with similar proportion among them. This shows that active recommendation is essential to increase the number of adherents to vaccination, this being a strategy already commented previously by other authors.14 While the first is so important, it is probable, in our opinion, that this fear would be lower the years after the pandemic because of the seasonalization of SARS-CoV-2. On the other hand, it was surprising that the people accepted to be vaccinated against fly when we offered a serological test for SARS-CoV-2 and influenza. However, this decoy does not seems to be a cost-effective tool for gaining influenza vaccine followers. Those three reasons were more frequently answered by people without comorbidities.
Regarding the reasons for continuing to be vaccinated in those who had previously done so, the vast majority defended that they did so because they were already adherent to vaccination every year, and therefore they did not need more reasons to continue doing so. In this sense, the people who had already verified the benefits of vaccination, the minimal adverse effects and the advantages of carrying out this act every year, had included it as another routine in their lives. Once again, the medical recommendation in those who were hesitant was crucial to include the 7.3% of people who had previously been vaccinated. For this group, we observed that the proportion of the people without comorbidities responded more frequently that they were adherent to vaccination, but the people with comorbidities responded more frequently that they are likely to be vaccinated because they fell that they are a risk group.
In our opinion, despite of vaccination to healthy adults is not included as a recommendation in most European countries, there are evidence that vaccinating the working-age population would be beneficial for the whole population. For example, in a work conducted in Belgium using compartmental transmission model, the authors showed that vaccination of 90% of workers may reduce the burden of influenza in the workplace and in the community population at least six-fold compared to 10% of vaccine coverage.9 For that, and taking the results of our survey, it is necessary to reinforce the implication of medical staff to involve more workers to vaccination.
One of the main limitations of our work is that was conducted during the COVID-19 pandemic and probably a higher number of participants were vaccinated against influenza due to the fear of coinfection. Also, that there was no available information on the participants regarding their job position, training, and other sociodemographic variables, which could have shown different opinions and reasons for getting vaccinated or not. Also, that given the survey was self-limited to several answers, we cannot now the opinions different to these options. Finally, we do not have the demographic and clinical information of the workers of the factory that were not vaccinated, so we couldn't perform a vaccine coverage analysis on the different parameters included in the study.
ConclusionsIn conclusion, our study shows that the active medical recommendation on influenza disease is the best way to increase the vaccine coverage in healthy worker adults, and also that, if a person is vaccinated one time, it is more probable that would get the vaccine the next year. On the other hand, in people not previously vaccinated, the fear of the co-infection of COVID-19 and Influenza during the pandemic was important for selecting being vaccinated against flu for the first time.
FundingThis work funded by RENAULT ESPAÑA S.A. company.
Author contributionsISM, LTF and JME design the study; LTF, CL, JIE and ACP recruited the samples and obtained the information of the workers; ISM and JME performed the analysis; ISM and JME written the manuscript; ISM, JME, LTF, CL, JIE and ACP revised the manuscript. All the authors revised and approved the final version of the manuscript.
Ethics and informed consentThis work was approved by the Ethics Committee of the Eastern Health Area of Valladolid (Cod: PI 21–2442). All participants signed a written informed consent prior to obtain the survey information.
We thank all the staff involved in the study that recruited the workers and that performed the survey.
