Influenza vaccine hesitancy and acceptance among healthcare workers: A qualitative study in Amsterdam, the Netherlands / Grippeimpfung: Skepsis und Akzeptanz bei Gesundheitsfachkräften. Eine qualitative Studie aus Amsterdam, Niederlande

This qualitative study drew on the 5C model of vaccine hesitancy, a widely used theoretical framework consisting of five domains. Confidence is described as “trust in (i) the effectiveness and safety of vaccines; (ii) the system that delivers them, including the reliability and competence of the health services and health professionals; and (iii) the motivations of policy-makers who decide on the needed vaccines” (MacDonald & SAGE Working Group on Vaccine Hesitancy, 2015). Complacency “exists where perceived risks of vaccine-preventable diseases are low and vaccination is not deemed a necessary preventive action” (MacDonald & SAGE Working Group on Vaccine Hesitancy, 2015). Constraints are a problem when “physical availability, affordability and willingness-to-pay, geographical accessibility, ability to understand (language and health literacy) and appeal of immunization services affect uptake” (MacDonald & SAGE Working Group on Vaccine Hesitancy, 2015). Calculation is described as the “individuals' engagement in extensive information searching” (Betsch et al., 2018). Collective responsibility is “the willingness to protect others by one's vaccination by means of herd immunity” (Betsch et al., 2018).

Interviews were conducted with healthcare workers of the Amsterdam UMC, an academic medical center with over 19,500 employees. Annual influenza vaccination campaigns are conducted to promote vaccine uptake. The study focused on several departments with clients at particular risk of influenza-related morbidity and mortality. Eleven departments were approached to participate in the study, of which four agreed to participate: cardiology, nephrology, geriatrics and pediatrics. The remaining departments did not respond to the invitation.

Healthcare workers were defined according to the Dutch National Institute for Public Health and Environment (RIVM)'s target definition, which is “healthcare workers aged 18 and over who have direct contact with clients, including trainees, apprentices, agency workers and freelancers” (Rijksinstituut voor Volksgezondheid en Milieu, 2021). Purposive sampling through heads of departments was used to ensure the participation of healthcare workers from different backgrounds, and to build trust and encourage participation.

The interview guide was designed using both the European Centre for Disease Prevention and Control's guide for vaccine hesitancy among healthcare workers and the 5C vaccine hesitancy model (Betsch et al., 2018; European Centre for Disease Prevention and Control, 2015). A comparison was also made with the hepatitis B vaccine, which is mandatory for healthcare workers at risk of exposure to the virus (Rijksinstituut voor Volksgezondheid en Milieu, 2013). This comparison provided insights into the role of mandatory vaccination in this context. In addition, the interview guide was piloted with two healthcare workers, after which minor changes were made. The interview guide can be found in Appendix 1.

Semi-structured interviews were conducted to explore healthcare workers' experiences and perspectives on influenza vaccination. The interviews were conducted by a Master's student in health sciences trained in qualitative research. They had to be kept relatively short, lasting approximately 30 minutes because healthcare workers are busy and their time is limited. The interviews were conducted either online or in person, depending on the participant's preference. All interviews were conducted in Dutch.

The interviews were recorded and transcribed verbatim. and the transcripts were coded using ATLAS.ti software, which allowed for a systematic analysis of the data. The interviews were mostly deductively coded, based on the five main domains of the 5C vaccine hesitancy model and their subcategories. In addition, there was an inductive element, with new codes added to capture emerging themes. For their inclusion in the results section, excerpts of the interviews were translated into English by the first author, who is a native Dutch speaker with advanced English-language proficiency.

A number of measures were taken to ensure the validity and reliability of the study. First, to ensure that the questions were relevant to the purpose of the study and that the same codes were applied consistently, the interview guide and codebook were reviewed by two secondary researchers with experience in the field. This also increased credibility and reduced potential bias. In addition, to avoid further potential bias and capture a broad perspective of both vaccinated and unvaccinated healthcare workers, a neutral approach was employed. Vaccination status was not asked prior to the interview, and emphasis was placed on gaining insights into the overall vaccination policy at the Amsterdam UMC.

This research is not subject to the Medical Research Involving Human Subjects Act (WMO). A BETCHIE self-test was conducted to determine if ethical clearance was necessary. The secretariat of the METC Amsterdam UMC was also consulted. Based on the results, ethical approval was not required for this research. Participants were asked to sign an informed consent form prior to their interview. In addition, permission was sought to record and transcribe the meeting.

Influenza vaccination at the Amsterdam UMC is a yearly occurrence offered to staff. For this reason, those who have been working at the hospital for several years are more likely to be familiar with these services. They have had multiple opportunities to be vaccinated, and the extent to which they have taken advantage of this varies between regular, occasional, and not at all. This may be more complicated for newly qualified healthcare workers because they have had less exposure to these services. Of the 12 vaccinated participants, five had used ad-hoc services in the past year, five had been vaccinated by peers in the department, and two had been vaccinated by their general practitioner due to underlying health problems. The results of the interviews are presented following the domains of the 5C vaccine hesitancy model.

One of the main findings from this study was that half of the participants did not consider themselves at risk of contracting influenza, or believed that their immune system could manage the consequences, indicating a higher level of Complacency (Betsch et al., 2018). This is consistent with the literature, which highlights how influenza vaccine hesitancy among healthcare workers is often related to low perceived susceptibility (Dini et al., 2017; Guillari et al., 2021; Mannocci et al., 2010; Schmid et al., 2017). In addition, non-pharmaceutical measures to prevent influenza were cited more often than vaccination, suggesting that vaccination is not seen as an essential preventive measure (Galagali et al., 2022).

In line with the domain of Collective responsibility, all participants recognized the potential for occupational transmission and acknowledged that vaccination could indirectly protect patients (Betsch et al., 2018). Thus, the problem seems to be a belief that if they do not get sick, they cannot transmit the virus either — leading them, once again, to not prioritize vaccination. However, 28–59% of influenza infections are subclinical, contributing substantially to the unintentional spread of the virus (Flegel, 2012; Guillari et al., 2021; Pereira et al., 2017). Therefore, actions based on symptoms – “if I get sick, I will stay home” or “if I experience symptoms, I will use non-pharmaceutical preventative measures” – are less likely to prevent onward transmission.

These findings indicate that there are misconceptions and limited understanding of the problem, which is consistent with other research (Mannocci et al., 2010). As a result, healthcare workers may unintentionally infect their patients, despite their intention to protect them, due to a lack of awareness of the risks and transmission of influenza. Education could play a significant role in addressing this gap because most of the participants pointed to a lack of evidence in current information provision and expressed a need for more comprehensive figures.

In addition, the participants showed low levels of Calculation, as they did not search for additional information from sources other than the Amsterdam UMC (Betsch et al., 2018). Nonetheless, they highly valued the provision of information, as it influenced their decision-making every year. If healthcare workers are not well-informed on the topic, or if they are suspicious, they are more likely to engage in additional research, such as conducting online searches. However, it may be easier to stumble across misinformation, which is often driven by emotional or conspiracy-driven narratives (Brainard & Hunter, 2020). Consequently, it is important to address misconceptions in order to mitigate the search for, spread of, and susceptibility to misinformation (Lewandowsky et al., 2012).

Furthermore, the participants demonstrated high levels of Confidence in the Amsterdam UMC, the organization responsible for administering the vaccines and providing them with information (Betsch et al., 2018). This suggests that regularly updated and accurate information could increase healthcare workers' acceptance (Jiang et al., 2023; Souza et al., 2022). Providing healthcare workers with the right information could potentially increase their willingness to accept the vaccine.

However, even when healthcare workers have the necessary knowledge, coverage remains low if vaccination services are inaccessible or unknown. To improve vaccination coverage, vaccination should be made as convenient as possible by solving the current Constraints, which exist mainly around the ad hoc services (Betsch et al., 2018). Limited availability of dates and time slots, and the need for appointments in the first place, currently hamper efficient access to vaccinations. This is in spite of efforts by the hospital to reduce accessibility barriers. In addition, unlike the hepatitis B and COVID-19 vaccines, which may only require a booster dose, influenza vaccination is not a onetime event and must be repeated annually. Therefore, the constraints seem to recur each year. This, combined with the consistently high workload, can make it difficult to provide easy access to vaccination.

These findings are consistent with previous studies addressing the lack of availability of influenza vaccination services (Jessop et al., 2017; Lewthwaite et al., 2014). On a positive note, participants who had received vaccination in the ward from peers expressed a more favorable experience, suggesting that expanding this service to every ward could potentially increase vaccination coverage.

Lastly, some participants reported not receiving an invitation, which discouraged vaccination. Effective communication is crucial to raise awareness and to encourage healthcare workers, whether permanent or temporary, to get vaccinated (European Centre for Disease Prevention and Control, 2019). This is particularly important because the number of self-employed within the health and welfare sector is increasing each year and falls within the target group of the National Institute for Public Health and Environment (RIVM) (Rijksinstituut voor Volksgezondheid en Milieu, 2021).

Through qualitative methods, we were able to examine in-depth factors associated with influenza vaccine hesitancy and acceptance among healthcare workers. The respondents include healthcare workers of various ages and functions. One limitation was that two-thirds of respondents had received the influenza vaccination in the past year, which is more than double the 29% vaccination rate observed in 2022 in the Amsterdam UMC (Maas, J, 2022). As a result, negative perspectives on influenza vaccination may be underrepresented. However, because of the annual nature of influenza vaccination, vaccination status varies over time, and current vaccination status does not always indicate complete acceptance or refusal of the vaccine. Additionally, because the influenza vaccination campaign was conducted in the autumn of 2023 — around six months before data collection — some respondents experienced challenges in recalling their experiences. Lastly, only four out of the 11 invited departments at the Amsterdam UMC participated in this study. Therefore, the findings of this study may not be representative at the hospital level.

Previous research has demonstrated that multifaceted campaigns are most effective in increasing vaccination coverage (Hollmeyer et al., 2013; Schumacher et al., 2023). Using multiple interventions, a campaign is more likely to have an impact on several domains of the 5C hesitancy model. Although each domain influences vaccination behavior directly, the findings of this study illustrate their inter-relationships. For healthcare workers, complacency fosters a particular type of collective responsibility that underestimates the risk of transmission. This perception is exacerbated by a lack of awareness of asymptomatic transmission. Complacency also leads to lower levels of calculation, reducing interest in the benefits of vaccination and limiting information-seeking. Taking this interrelatedness into account is likely key to the (sustained) impact of strategies to increase vaccine uptake.

This study also revealed that it is important that healthcare workers choose influenza vaccination from intrinsic motivation rather than out of a sense of coercion. The hospital has undertaken various efforts to increase influenza vaccination coverage, including incentives (such as the croquette), increasing ease of access, and highlighting role models for vaccinations. Although the campaign involving the croquette was mentioned, other methods were not identified by respondents. The findings of this study indicate that there are two main areas in which efforts should be focused to increase vaccination coverage among healthcare workers at Amsterdam UMC. These two organizational strategies are expected to eliminate practical barriers and strengthen healthcare workers' intrinsic motivation to receive the vaccine annually.

More and tailored information.

To provide more comprehensive and tailored information, it would be beneficial to conduct clinical lessons given by infectious disease and vaccination experts, and to expand information letters about vaccination with more facts and figures. One of the key issues to address is subclinical transmission because many participants are unaware of this phenomenon. Using more infographics could help draw attention to it. In addition, promotion through flyers, posters, banners and e-mail should start earlier in the process. All of these materials could include QR codes for quick and easy registration.

In future research, it may be useful to have an adaptation of the 5C hesitancy model specifically for influenza. Compared to vaccination for other diseases, influenza vaccination poses unique challenges, particularly due to influenza's annual recurrence. As a result, health workers are constantly making calculations and weighing benefits and risks. The domain of calculation should therefore play a more central role within a framework in which the other domains influence calculation (Lam et al., 2010). Also, influenza vaccination campaigns often consist of several components, making it difficult to assess the key intervention and its impact. Therefore, to optimize future campaign strategies, there is a need to evaluate the impact of specific interventions through clustered, randomized trials or case-control studies.