https://orcid.org/0000-0002-5687-6621
ABSTRACT
Background: Vaccination of primary healthcare workers (PHCWs) help to prevent the spread of influenza among at-risk patients.
Objectives: To assesses seasonal influenza vaccination (SIV) coverage and the factors affecting SIV’s utilization among PHCWs in Abha city, southwestern Saudi Arabia.
Methods: A cross-sectional survey was carried out between June 2018 and August 2018 in all primary healthcare centers in Abha city. It targeted physicians, nurses, technicians, and pharmacists. A self-administered questionnaire was used to collect data regarding SIV status during the 2017–2018 season, obtain knowledge regarding SIV and influenza disease, and identify potential motivators for and barriers to SIV.
Results: Of 312 PHCWs, the SIV coverage rate was 45.5% in the 2017–2018 vaccination season. A multivariable logistic regression model showed that the risk groups for non-vaccination were PHCWs less than 40 years old (adjusted Odds Ratio (aOR) = 4.07, 95% CI: 1.50–11.03), technicians (aOR = 3.73, 95% CI: 1.20–11.54), single PHCWs (aOR = 2.36, 95% CI:1.20–4.62), and PHCWs lacking adequate influenza vaccine knowledge (aOR = 4.22, 95% CI: 2.13–8.35). Approximately 23% and 32% of PHCWs were found to have inadequate knowledge about SIV and influenza disease, respectively. PHCWs’ awareness about their risk of infection and their need for protection was found to be the most common motivator (77.5%), and a fear of side effects was found to be the most frequent barrier (40%).
Conclusion: SIV coverage rate is suboptimal. Knowledge gaps and misconceptions about the influenza vaccine are the main barriers to an adequate coverage.
Introduction
Seasonal influenza is an infectious respiratory disease that causes a worldwide public health problem due to its complications and high subsequent mortality rate particularly among at risk patients. These have caused all levels of health services to be overburdened during severe epidemics.Citation1–Citation3 A systematic review and meta-analysis found that healthcare workers (HCWs) are at a significantly greater risk of influenza infection compared to adults working in non-healthcare settings.Citation4 Furthermore, primary healthcare workers (PHCWs) who provide care to patients may help to transmit the infection to their patients, friends, and family members.Citation5
Influenza vaccination is an essential tool for the prevention of influenza. Vaccination of HCWs is an important strategy for reducing the transmission of influenza from health care staff to their patients and families.Citation6 Moreover, PHCWs can positively motivate their patients by following self-prevention procedures and receiving the vaccination themselves.Citation7 The prevention of influenza among PHCWs via vaccination provides additional protection to patients with chronic disease who access primary healthcare centers and are at risk of complications from influenza.Citation8 Therefore, it is highly recommended that healthcare facilities adopt adequate policies and perform actions to encourage influenza vaccinations for HCWs.Citation9 However, the vaccination coverage among HCWs remains suboptimal in many countries. In the 2017–2018 influenza season, the coverage rate among HCWs was 40.2% in Greece,Citation10 68.7% in England,Citation11 78.4% in the United States,Citation12 and low in most countries of the Eastern Mediterranean Region.Citation13
Although the Saudi Ministry of Health provides a seasonal influenza vaccine to all PHCWs and patients free-of-charge,Citation14 the vaccination rate among HCWs in the 2017–2018 influenza season was low (55.9%).Citation15
Studying the obstacles to, and motivators of, vaccination among PHCWs is important to enhancing seasonal influenza vaccination (SIV) coverage. The most-reported motivators include self-protection and the protection of family members,Citation16 while the most commonly reported obstacles are inadequate knowledge about the vaccine and misconceptions about the vaccine’s effectiveness and adverse effects.Citation17
There are few data on the SIV coverage rate and its determinants among PHCWs in southwestern Saudi Arabia. This survey assessed the SIV coverage rate and the factors affecting SIV’s utilization among PHCWs in southwestern Saudi Arabia. It also explores the barriers to and motivators of SIV uptake.
Methods
Survey design and setting
A cross-sectional survey was carried out at primary healthcare centers (PHCCs) in Abha city, southwestern Saudi Arabia. There are 11 PHCCs in Abha City. They provide primary health care services to approximately 421,921 persons.
Survey population
The survey targeted all physicians, nurses, technicians, dentists, and pharmacists working at the 11 PHCCs in Abha city. The survey was conducted between June 2018 and August 2018. All PHCWs working at the above-mentioned PHCCs were invited to participate in the survey.
Survey tools and data collection
A specially designed questionnaire was developed after the relevant literature was reviewed. Face content validity was assessed and approved by a panel of experts in Family Medicine, Community Medicine, Biostatistics, and Preventive Medicine. The questionnaire was composed of the areas: (a) personal and work characteristics, such as age, gender, job title, specialty, years of experience, qualifications, and the presence of chronic disease, such as diabetes mellitus, hypertension, ischemic heart disease, chronic respiratory disease, and chronic kidney disease; (b) influenza vaccine uptake in the 2017–2018 influenza season; (c) questions to evaluate knowledge regarding SIV and influenza disease; and (d) potential motivators for and barriers to influenza vaccination in the survey year.
Seven questions and six questions were used to assess knowledge about the influenza vaccine and disease, respectively. The vaccine knowledge questions included questions on the nature of the vaccine, the frequency of uptake, the vaccine’s effectiveness, possible side effects, and contraindications. The influenza knowledge questions covered the following areas: high risk groups, methods of transmission and prevention, and complications. A participant was considered to have adequate knowledge on the vaccine and the disease when they correctly answered at least four of the questions in each set. The anonymous questionnaire was self-reported by the participants. Only personnel who were vaccinated were asked about motivators for vaccination, and only personnel who were not vaccinated were asked about barriers to vaccination.
Participants from each PHCC were identified using human resources records. The authors disseminated the self-reported questionnaire among the participants in person.
Data entry and analysis
The obtained data were entered, double-checked, refined, and analyzed using SPSS version 22 (IBM, North Castle, NY, USA). Categorical variables are presented as a number and a percentage and compared by chi-squared test. A univariate analysis was carried out to calculate the crude odds ratio (cOR) of being unvaccinated and the 95% confidence intervals (95% CIs). A logistic regression model was used to evaluate the significant independent factors associated with participants’ seasonal influenza non-vaccination during the survey season. Adjusted odds ratios (aORs) of being unvaccinated and their 95% CI were calculated. The dependent variable was SIV status in the in the 2017–2018 influenza season (non-vaccinated = 1 and vaccinated = 0) The independent variables that were included in the model were: age, sex, job title, experience, level of education, marital status, smoking status, presence of chronic disease, vaccine knowledge, and influenza disease knowledge.
Results
Description of the survey participants
The survey involved 312 of the 390 primary healthcare workers (PHCWs) in Abha city. The overall response rate was 80.3% (77% for physicians, 86% for nurses, 83% for technicians, 75% for dentists, and 83% for pharmacists). The main reason for nonparticipation was absence at the time of the visit to the PHCC. The PHCWs’ age ranged from 22 to 65 years with a median of 31 years. More than half of the participants were females (181, 58.0%). The survey sample included 74 (23.7%) physicians, 123 (39.4%) nurses, 68 (21.8%) technicians, 30 (9.6%) pharmacists, and 17 (5.4%) dentists. Their years of experience ranged from 1 to 41 years with a median of 8 years. Most of the participants have a secondary school diploma (140, 44.9%) or a bachelor’s degree (139, 44.6%). A minority have a post graduate degree (33, 10.6%). A majority of the participants were married (230, 73.7%), nonsmokers (276, 88.5%), and did not suffer from a chronic disease (272, 87.2%).
Seasonal influenza vaccination coverage rate
Less than half (n = 142) of the survey participants were vaccinated against seasonal influenza in the 2017–2018 vaccination season (a coverage rate of 45.5%).
Factors associated with influenza non-vaccination
describes the univariate analysis the and multivariable analysis for the factors associated with influenza non-vaccination. The multivariable analysis shows that the risk of non-vaccination was higher among participants less than 40 years old (aOR = 4.07, 95% CI: 1.50–11.03), technicians (aOR = 3.73, 95% CI: 1.20–11.54), single PHCWs (aOR = 2.36, 95% CI: 1.20–4.62), and those lacking adequate influenza vaccine knowledge (aOR = 4.22, 95% CI: 2.13–8.35). On the other hand, influenza disease knowledge and presence of chronic disease were not associated with vaccination uptake among the survey participants.
Table 1. Univariate analysis and multivariable analysis for factors associated with seasonal influenza non-vaccination in the survey participants (n = 312).
Knowledge about the influenza vaccine and influenza disease
Approximately one-fourth of the survey participants (74, 23.05%) were inadequately knowledgeable about the influenza vaccine. Inadequate knowledge was higher among pharmacists (10, 33.3%), technicians (21, 30.9%), nurses (36, 29.3%), and dentists (4, 23.5%) compared to physicians (3, 4.1%). On the other hand, non-significant relationships were observed for age, sex, experience, marital status, qualifications, and health status ().
Table 2. Factors associated with non-satisfactory knowledge of influenza vaccine and disease in the survey participants (n = 312).
One-third of the participants (102, 32.7%) were inadequately knowledgeable about influenza disease. Non-satisfactory knowledge was higher among diploma (54, 38.6%) and bachelor (43, 30.9%) graduates as compared to postgraduates (5, 15.2%). Also, nurses (51, 41.5%), technicians (28, 41.2%), and pharmacists (11, 36.7%) reported higher non-satisfactory knowledge compared to dentists (3, 17.6%) and physicians (9, 12.2%). On the other hand, non-significant relations were observed for age, sex experience, marital status, and health status ().
Motivators for and barriers to seasonal influenza vaccination
shows the motivators for seasonal influenza vaccination (SIV) and barriers to vaccination in the survey participants. The most commonly reported motivators for SIV were awareness about the risk of influenza infection (110, 77.5%), a tendency to avoid disease transmission to family members (89, 62.7%), and in response to infection control instructions (86, 60.6%). Among PHCWs reporting a chronic disease (n = 23), 69.6% cited this as a motivation for receiving an influenza vaccine. As to barriers, a fear of side effects (40%), a false perception that vaccination is not important (24.1%), and unsatisfactory past experience (17.6%) were the most frequently stated barriers among unvaccinated participants.
Table 3. Motivators for and barriers to seasonal influenza vaccination in the survey participants (n = 312).
Discussion
The findings of the present survey provide us with insight into the SIV status among primary healthcare workers (PHCWs) in southwestern Saudi Arabia. They show that less than half (45.5%) of the PHCWs were vaccinated in the 2017–2018 vaccination season. This result reveals an increasing trend regarding the SIV coverage rate among healthcare professionals in Saudi Arabia. It is higher than that reported among healthcare workers for the 2012–2013 vaccination season (38%)Citation18 and for the 2008–2009 vaccination season (34%).Citation14 Compared to the vaccination coverage reported from other gulf regions, it is higher than that reported from Qatar (35%) in 2014Citation19 and United Arab Emirates (24.7%)Citation20 but lower than that reported from Kuwait (67.2%)Citation20 and close to that reported from Oman (46.4%).Citation20 The findings of a previous study suggest that a coverage rate of 80% of HCWs may be adequate to minimize disease transmission and maintain herd immunity at a safe level in health care settings.Citation21 Although, SIV is available and accessible to, and free-of-charge for, all PHCWs in Saudi Arabia, the uptake rate is still lower than the proposed target of 80%. A strategy of compulsory influenza vaccination as a condition of work in health care settings could improve SIV uptake.Citation22 Also, the Task Force on Community Preventive Services recommends on-site, free, and actively promoted vaccinations to increase the coverage rate among HCWs.Citation23
Our survey suggests that the risk of non-vaccination is higher among younger PHCWs (less than 40 years old). This result is in accordance with the findings of studies conducted in Oman,Citation20 Qatar,Citation24 Malaysia,Citation25 Belgium,Citation16 Hungary,Citation26 Spain,Citation27 and Saudi Arabia.Citation15 Older age is one of the important predictors of influenza uptake among HCWs. Older HCWs tend to protect themselves via influenza vaccine. They are aware of their vulnerability to influenza and appreciate the benefits of the vaccine.Citation28
In the current survey, technicians were found to be less likely to vaccinate compared to physicians. A similar result was reported among HCWs in the United States in the 2014–2015 influenza season.Citation29 Technicians reported lower level of knowledge about both influenza disease and the influenza vaccine and that appears to be a risk factor for non-vaccination.
Our results revealed that single PHCWs are also less likely to obtain the vaccine compared to married PHCWs. Previous studies have shown that subjects who live alone and are not married form a risk group for seasonal influenza vaccination.Citation30,Citation31
Our results also reveal that PHCWs who lack adequate influenza vaccine knowledge form a risk group for low vaccine uptake. This confirms the results obtained in previous studies that reported a low vaccination rate among HCWs with insufficient knowledge about the influenza vaccine.Citation32,Citation33 One of the important findings of the present survey that could help to explain the relatively low uptake of the vaccine is the considerable gap in knowledge about the influenza vaccine and influenza disease among the studied PHCWs. This result is consistent with the findings of previous studies.Citation14,Citation32 Therefore, it is worth enhancing HCWs’ knowledge about their role in disease transmission and the value of the influenza vaccine in order to correct misconceptions and ensure vaccine safety.Citation32
Our results reveal that the most commonly reported motivators for seasonal influenza vaccination are: PHCWs’ awareness that they are at risk of influenza infection and need protection (77.5%), the presence of chronic disease (69.6%), and a tendency to protect family members (62.6%). These results are similar to those reported in studies from Saudi ArabiaCitation15 and other countries.Citation20,Citation34 Also, response to infection control instructions was found to be an important motivator for vaccine uptake in the present survey. According to the Saudi Ministry of Health’s infection control guidelines, an influenza vaccine should be recommended and provided free-of-charge to all HCWs.Citation14 Motivators are the main predictors of vaccine acceptance and uptake. Expanding the number of PHCWs who have these motivators by educational campaigns as part of a multi-component intervention is important to increasing the vaccination rate.Citation32,Citation35
As to barriers, our results show that a fear of side effects (40%) and a false perception that vaccination is not important (24.1%) were the most frequently stated barriers among unvaccinated participants. These barriers are based on misconceptions and a lack of knowledge.Citation18,Citation24,Citation27 Misconceptions can be reduced through a well-planned educational program. Overcoming misperceptions by clarifying the facts about SIV could improve its uptake.Citation16
The present survey provides important information about the SIV coverage rate and factors that affect it. It also highlights the most important motivators for and barriers to vaccination among PHCWs in Saudi Arabia. This information could be generalized to similar populations to enhance vaccination coverage.
This survey has some limitations that are linked to its design. First, vaccination uptake was self-reported by participants and not verified by vaccination records, this tends to overestimate vaccination coverage rate. Second, information recall bias is possible; however, the survey was conducted between June 2018 and August 2018 during the same influenza season. This limited amount of time could minimize the probability of a wrong report. Another limitation is related to the cross-sectional nature of the survey. This design reflects the current SIV status and does not describe changes across time. In addition, the findings are not representative of all Saudi PHCWs, as we included only those in one region of the country.
In conclusion, the influenza vaccination coverage rate among PHCWs in southwestern Saudi Arabia remains suboptimal. Knowledge gaps and misconceptions about the influenza vaccine are the main barriers to an adequate SIV coverage rate. The role of improving HCWs’ knowledge in enhancing vaccination coverage should be examined by interventional studies. Also, a strategy of compulsory influenza vaccination as a condition of work in primary health care settings could be attempted to improve the uptake.
Abbreviations
| SIV | = | Seasonal influenza vaccination |
| aOR | = | Adjusted odds ratio |
| cOR | = | Crude odds ratio |
| CIs | = | Confidence intervals |
| HCW | = | Health care workers |
| PHCCs | = | Primary healthcare centers |
| PHCWs | = | Primary healthcare workers |
Disclosure of potential conflicts of interest
The authors declare no conflicts of interest.
Ethical approval
The survey was conducted in accordance with the Declaration of Helsinki. The research proposal was approved by the Ethics and Research Committee of the College of Medicine of King Khalid University (ERC# 2018-04-07). Approval was attained from the directorate of the Health sector in Abha City prior to data collection. Oral consent was obtained from each PHCW after a warranty was provided on the confidentiality of the reported data.
Ethical considerations
The survey was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics and Research Committee of the College of Medicine of King Khalid University
Additional information
Funding
References
- Jorgensen P, Mereckiene J, Cotter S, Johansen K, Tsolova S, Brown C. How close are countries of the WHO European Region to achieving the goal of vaccinating 75% of key risk groups against influenza? Results from national surveys on seasonal influenza vaccination programmes, 2008/2009 to 2014/2015. Vaccine. 2018;36:442–52. doi:10.1016/j.vaccine.2017.12.019.
- Reed C, Chaves SS, Daily Kirley P, Emerson R, Aragon D, Hancock EB, Butler L, Baumbach J, Hollick G, Bennett NM, et al. Estimating influenza disease burden from population-based surveillance data in the United States. PLoS One. 2015;10:e0118369. doi:10.1371/journal.pone.0118369.
- Van Cauteren D, Vaux S, de Valk H, Le Strat Y, Vaillant V, Lévy-Bruhl D. Burden of influenza, healthcare seeking behaviour and hygiene measures during the A (H1N1) 2009 pandemic in France: a population based study. BMC Public Health. 2012;12:947. doi:10.1186/1471-2458-12-947.
- Kuster SP, Shah PS, Coleman BL, Lam -P-P, Tong A, Wormsbecker A, McGeer A, Sambhara S. Incidence of influenza in healthy adults and healthcare workers: A systematic review and meta-analysis. PLoS One. 2011;6:e26239. doi:10.1371/journal.pone.0026239.
- Music T. Protecting patients, protecting healthcare workers: a review of the role of influenza vaccination. Int Nurs Rev. 2012;59:161–67. doi:10.1111/j.1466-7657.2011.00961.x.
- Hayward AC. Influenza vaccination of healthcare workers is an important approach for reducing transmission of influenza from staff to vulnerable patients. PLoS One. 2017;12:e0169023. doi:10.1371/journal.pone.0169023.
- Frank E, Breyan J, Elon L. Physician disclosure of healthy personal behaviors improves credibility and ability to motivate. Arch Fam Med. 2000;9:287–89. doi:10.1001/archfami.9.3.287.
- Çiftci F, Şen E, Demir N, Çiftci O, Erol S, Kayacan O. Beliefs, attitudes, and activities of healthcare personnel about influenza and pneumococcal vaccines. Hum Vaccin Immunother. 2018;14:111–17. doi:10.1080/21645515.2017.1387703.
- Nessler K, Krztoń-Królewiecka A, Chmielowiec T, Jarczewska D, Windak A. Determinants of influenza vaccination coverage rates among primary care patients in Krakow, Poland and the surrounding region. Vaccine. 2014;32:7122–27. doi:10.1016/j.vaccine.2014.10.026.
- Maltezou HC, Katerelos P, Protopappa K, Dounias G. Seasonal influenza vaccination in healthcare personnel in Greece: 3-year report. Future Microbiol. 2019;14:55–58.
- Stead M, Critchlow N, Patel R, MacKintosh AM, Sullivan F. Improving uptake of seasonal influenza vaccination by healthcare workers: implementation differences between higher and lower uptake NHS trusts in England. Infect Dis Health. 2019;24:3–12. doi:10.1016/j.idh.2018.09.082.
- Black CL, Yue X, Ball SW, Fink RV, de Perio MA, Laney AS, Williams WW, Graitcer SB, Fiebelkorn AP, Lu P-J, et al. Influenza vaccination coverage among health care personnel—United States, 2017–18 influenza season. MMWR Morb Mortal Wkly Rep. 2018; 67:1050. doi:10.15585/mmwr.mm6738a2.
- Abubakar A, Melhem N, Malik M, Dbaibo G, Khan WM, Zaraket H. Seasonal influenza vaccination policies in the Eastern Mediterranean Region: current status and the way forward. Vaccine. 2019;37:1601–07. doi:10.1016/j.vaccine.2019.02.001.
- Rehmani R, Memon JI. Knowledge, attitudes and beliefs regarding influenza vaccination among healthcare workers in a Saudi hospital. Vaccine. 2010;28:4283–87. doi:10.1016/j.vaccine.2010.04.031.
- Reda Alenazi B, Mohamed Hammad S, Elwan Mohamed A. Prevalence of seasonal influenza vaccination among primary healthcare workers in Arar city, Saudi Arabia. Electronic Physician. 2018;10:7217–23. doi:10.19082/7217.
- Boey L, Bral C, Roelants M, De Schryver A, Godderis L, Hoppenbrouwers K, Vandermeulen C. Attitudes, believes, determinants and organisational barriers behind the low seasonal influenza vaccination uptake in healthcare workers – A cross-sectional survey. Vaccine. 2018;36:3351–58. doi:10.1016/j.vaccine.2018.04.044.
- Bali NK, Ashraf M, Ahmad F, Khan UH, Widdowson M-A, Lal RB, Koul PA. Knowledge, attitude, and practices about the seasonal influenza vaccination among healthcare workers in Srinagar, India. Influenza Other Respi Viruses. 2013;7:540–45. doi:10.1111/j.1750-2659.2012.00416.x.
- Alshammari TM, AlFehaid LS, AlFraih JK, Aljadhey HS. Health care professionals’ awareness of, knowledge about and attitude to influenza vaccination. Vaccine. 2014;32:5957–61. doi:10.1016/j.vaccine.2014.08.061.
- Elawad KH, Farag EA, Abuelgasim DA, Smatti MK, Al-Romaihi HE, Al Thani M, Al Mujalli H, Shehata Z, Alex M, Al Thani A, et al. Improving influenza vaccination rate among primary healthcare workers in Qatar. Vaccines. 2017;5:36. doi:10.3390/vaccines5040036.
- Abu-Gharbieh E, Fahmy S, Rasool BA, Khan S. Influenza vaccination: healthcare workers attitude in three Middle East countries. Int J Med Sci. 2010;7:319. doi:10.7150/ijms.7.319.
- Salgado CD, Giannetta ET, Hayden FG, Farr BM. Preventing nosocomial influenza by improving the vaccine acceptance rate of clinicians. Infect Control Hosp Epidemiol. 2004;25:923–28. doi:10.1086/502321.
- Rakita RM, Hagar BA, Crome P, Lammert JK. Mandatory influenza vaccination of healthcare workers: a 5-year study. Infect Control Hosp Epidemiol. 2010;31:881–88. doi:10.1086/656210.
- Force CPST. Worksite: seasonal influenza vaccinations using interventions with on-site, free, actively promoted vaccinations—healthcare workers. Vaccination. The Community Guide organization website. 2019.
- Alhammadi A, Khalifa M, Abdulrahman H, Almuslemani E, Alhothi A, Janahi M. Attitudes and perceptions among the pediatric health care providers toward influenza vaccination in Qatar: A cross-sectional study. Vaccine. 2015;33:3821–28. doi:10.1016/j.vaccine.2015.06.082.
- Rashid ZZ, Jasme H, Liang HJ, Yusof MM, Sharani ZZM, Mohamad M, Ismail Z, Sulong A, Jalil NA . Influenza vaccination uptake among healthcare workers at a Malaysian teaching hospital. Southeast Asian J Tropical Med Public Health. 2015;46:215.
- Orosi P, Borbély Á, Szidor J, Sándor J. Factors affecting influenza vaccine uptake among health care workers in the Medical and Health Sciences Center of Debrecen University, Hungary. Orv Hetil. 2012;153:505–13. doi:10.1556/OH.2012.29328.
- Esposito S, Domínguez A, Godoy P, Castilla J, Soldevila N, Toledo D, Astray J, Mayoral JM, Tamames S, García-Gutiérrez S, et al. Knowledge of and attitudes to influenza vaccination in healthy primary healthcare workers in Spain, 2011–2012. PLoS One. 2013;8:e81200. doi:10.1371/journal.pone.0081200.
- Dini G, Toletone A, Sticchi L, Orsi A, Bragazzi NL, Durando P. Influenza vaccination in healthcare workers: A comprehensive critical appraisal of the literature. Hum Vaccin Immunother. 2017;14:772–89. doi:10.1080/21645515.2017.1348442.
- Black CL, Yue X, Ball SW, Donahue S, Izrael D, de Perio MA, Laney AS, Williams WW, Lindley MC, Graitcer SB, et al. Influenza vaccination coverage among health care personnel—United States, 2014-15 influenza season. MMWR Morb Mortal Wkly Rep. 2015;64:993–99. doi:10.15585/mmwr.mm6436a1.
- Nagata JM, Hernández-Ramos I, Kurup AS, Albrecht D, Vivas-Torrealba C, Franco-Paredes C. Social determinants of health and seasonal influenza vaccination in adults≥ 65 years: a systematic review of qualitative and quantitative data. BMC Public Health. 2013;13:388. doi:10.1186/1471-2458-13-388.
- Cowling BJ, Schmid P, Rauber D, Betsch C, Lidolt G, Denker M-L. Barriers of influenza vaccination intention and behavior – a systematic review of influenza vaccine hesitancy, 2005 – 2016. PLoS One. 2017;12:e0170550.
- Rabensteiner A, Buja A, Regele D, Fischer M, Baldo V. Healthcare worker’s attitude to seasonal influenza vaccination in the South Tyrolean province of Italy: barriers and facilitators. Vaccine. 2018;36:535–44. doi:10.1016/j.vaccine.2017.12.007.
- Tuckerman JL, Collins JE, Marshall HS. Factors affecting uptake of recommended immunizations among health care workers in South Australia. Hum Vaccin Immunother. 2015;11:704–12. doi:10.1080/21645515.2015.1008886.
- Petek D, Kamnik-Jug K. Motivators and barriers to vaccination of health professionals against seasonal influenza in primary healthcare. BMC Health Serv Res. 2018;18. doi:10.1186/s12913-018-3659-8.
- Jacob V, Chattopadhyay SK, Hopkins DP, Morgan JM, Pitan AA, Clymer JM. Community Preventive Services Task Force. Increasing coverage of appropriate vaccinations: a community guide systematic economic review. Am J Prev Med. 2016;50:797–808. doi:10.1016/j.amepre.2015.11.003.