|Year : 2021 | Volume
| Issue : 12 | Page : 543-554
Intention of healthcare workers to accept COVID-19 vaccination and related factors: A systematic review and meta-analysis
Petros Galanis1, Irene Vraka2, Despoina Fragkou1, Angeliki Bilali3, Daphne Kaitelidou4
1 Clinical Epidemiology Laboratory, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece
2 Department of Radiology, P & A Kyriakou Children's Hospital, Greece
3 Hospital Waste Management Unit, P & A Kyriakou Children's Hospital, Greece
4 Center for Health Services Management and Evaluation, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece
|Date of Submission||01-Aug-2021|
|Date of Decision||13-Dec-2021|
|Date of Acceptance||16-Dec-2021|
|Date of Web Publication||29-Dec-2021|
Clinical Epidemiology Laboratory, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens
Source of Support: None, Conflict of Interest: None
Considering medical and economic burden of coronavirus disease 2019 (COVID-19), a high COVID-19 vaccination coverage among healthcare workers (HCWs) is an urgent need. The aim of this systematic review and meta-analysis was to evaluate the intention of HCWs to accept COVID-19 vaccination and to identify related factors. We searched PubMed, MEDLINE, Scopus, Web of Science, ProQuest, CINAHL and medRxiv until July 14, 2021. The heterogeneity between results was very high; thus, we applied a random effects model to estimate pooled effects. We performed subgroup and meta-regression analysis to identify possible resources of heterogeneity. Twenty four studies, including 50 940 HCWs, met the inclusion criteria. The overall proportion of HCWs that intend to accept COVID-19 vaccination was 63.5% (95% confidence interval: 56.5%-70.2%) with a wide range among studies from 27.7% to 90.1%. The following factors were associated with increased HCWs' willingness to get vaccinated against COVID-19: male gender, older age, white HCWs, physician profession, higher education level, comorbidity among HCWs, vaccination against flu during previous season, stronger vaccine confidence, positive attitude towards a COVID-19 vaccine, fear about COVID-19, individual perceived risk about COVID-19, and contact with suspected or confirmed COVID-19 patients. The reluctance of HCWs to vaccinate against COVID-19 could diminish the trust of individuals and trigger a ripple effect in the general public. Since vaccination is a complex behavior, understanding the way that HCWs take the decision to accept or refuse COVID-19 vaccination will give us the opportunity to develop the appropriate interventions to increase COVID-19 vaccination uptake.
Keywords: COVID-19; Vaccination; Healthcare workers; Intention; SARS-CoV-2
|How to cite this article:|
Galanis P, Vraka I, Fragkou D, Bilali A, Kaitelidou D. Intention of healthcare workers to accept COVID-19 vaccination and related factors: A systematic review and meta-analysis. Asian Pac J Trop Med 2021;14:543-54
|How to cite this URL:|
Galanis P, Vraka I, Fragkou D, Bilali A, Kaitelidou D. Intention of healthcare workers to accept COVID-19 vaccination and related factors: A systematic review and meta-analysis. Asian Pac J Trop Med [serial online] 2021 [cited 2022 Oct 6];14:543-54. Available from: https://www.apjtm.org/text.asp?2021/14/12/543/332808
| 1. Introduction|| |
Coronavirus disease 2019 (COVID-19) pandemic causes a substantial number of deaths and has a tremendous impact on the world economy,. Globally, as of 15 July 2021, there have been more than 187 million cases of COVID-19 and more than 4 million deaths.
Seasonal influenza vaccination among healthcare workers (HCWs) is an effective infection control measure in healthcare settings,. Also, the importance of HCWs vaccination against H1N1 during the 2009/2010 influenza pandemic has already been reported,. Seasonal influenza immunization is a priority in countries with a high proportion of elderly,,. During the COVID-19 pandemic, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) have identified HCWs as a population with significantly elevated risk of being infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, there is a recommendation for the rapid and prioritized vaccination of HCWs against COVID-19 to protect them and the public health,,.
HCWs' vaccination against infectious diseases is of utmost importance to prevent the spread of viruses, especially in healthcare facilities with patients. A great number of studies have already addressed the factors that influence vaccines' acceptance by HCWs,,,,,. Several factors are identified in systematic reviews and meta-analyses such as desire for self-protection, desire to prevent illness in family or friends, perceived severity and risk of the disease, perceived safety and effectiveness of vaccination, more favorable attitudes toward vaccination, etc.
As the COVID-19 pandemic continues to grow due mainly to mutations and the low vaccination rate worldwide, the positive attitude of HCWs towards vaccination is crucial to build confidence in vaccines and promote acceptance in general population. Thus, we performed a systematic review and meta-analysis to estimate the intention of HCWs to accept COVID-19 vaccination and to find out related factors.
| 2. Materials and methods|| |
2.1. Data sources and strategy
We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines for this systematic review and meta-analysis. We searched PubMed, MEDLINE, Scopus, Web of Science, ProQuest, CINAHL and pre-print services (medRxiv) for articles published from January 1, 2020 to July 14, 2021. Through the databases, in the query box we used the following strategy in all fields: (((“health care worker*” OR “healthcare worker*” OR “healthcare personnel” OR “health care personnel” OR “health personnel” OR “health care professional*” OR “healthcare professional*” OR HCWS OR HCW OR HCPS OR HCP OR staff OR “nursing staff” OR employee* OR professional* OR personnel OR worker* OR doctor* OR physician* OR clinician* OR nurs* OR midwives OR midwife* OR paramedic* OR hospital* OR practitioner*) AND (vaccin*)) AND (intent* OR willing* OR hesitancy)) AND (COVID-19 OR COVID19 OR COVID OR SARS- CoV* OR “Severe Acute Respiratory Syndrome Coronavirus*” OR coronavirus*). Also, we examined reference lists of all relevant articles that we found during the search process. Finally, we removed duplicates.
2.2. Selection and eligibility criteria
Study selection was performed by two independent reviewers, while a third, senior reviewer resolved the discrepancies. Firstly, we screened title, then abstract of the records and finally the full-text. We applied the following inclusion criteria: studies examining HCWs' intention to accept COVID-19 vaccination and related factors; studies that were written in English; studies included all types of HCWs working in clinical settings. On the other hand, we excluded qualitative studies, reviews, case reports, protocols, editorials, and letters to the editor. Also, we excluded studies including students of health sciences, retired HCWs, patients, and general population.
2.3. Data extraction and quality assessment
We extracted the following data from each study: authors, location, sample size, age, gender, study design, sampling method, assessment of intention to accept COVID-19 vaccination, response rate, data collection time, type of publication (journal or pre-print service), number of HCWs with intention to accept COVID-19 vaccination, type of occupation (physicians, nurses, assistant nurses, paramedical staff, etc), factors related with intention to accept COVID-19 vaccination, and the level of analysis (univariate or multivariable). Assessment of intention to accept COVID-19 vaccination was referred to vaccine acceptance (e.g., binary yes/no answer, five or eleven point Likert-type scale). Perceived risk of COVID-19 is a combination of subjective perception of disease severity and susceptibility. Fear of COVID-19 among HCWs mainly includes fear of getting sick with the disease and fear of infecting patients, family members, and friends. Attitudes toward COVID-19 vaccination are defined as expressions of hesitancy or support measuring usually in Likert scales.
Two independent reviewers used the Joanna Briggs Institute critical appraisal tools to assess quality of studies (poor, moderate or good quality). An 8-point scale is used for cross-sectional studies with a score of ≤3 indicates poor quality, a score of 4-6 points indicates moderate quality, and a score of 7-8 points indicates good quality. The Joanna Briggs Institute critical appraisal tool for cross-sectional studies includes eight different assessment domains e.g., inclusion criteria for the sample, detailed description of the settings, exposure and outcome measurement, identification of confounding factors and strategies to eliminate them, and statistical analysis.
2.4. Statistical analysis
For each study, we divided the number of HCWs with intention to accept COVID-19 vaccination with the sample size to calculate the proportion of HCWs with intention to accept vaccination and the relative 95% confidence interval (CI). Then, we transformed the proportions with the Freeman-Tukey Double Arcsine method before pooling. Studies that used Likert scales to assess the intention to accept COVID-19 vaccination considered the answers “agree”/”strongly agree” as a positive answer. We used the I2 and Hedges Q statistics to assess between-studies heterogeneity. I2 values higher than 75% indicate high heterogeneity and a P-value <0.1 for the Hedges Q statistic indicates statistically significant heterogeneity. The heterogeneity between results was very high and thus we applied a random effect model to estimate pooled effects. We considered sample size, age, gender, response rate, data collection time, publication type (journal or pre-print service), type of occupation, studies quality, and the continent that studies were conducted as pre-specified sources of heterogeneity. Due to the limited variability of data in some variables, we decided to perform subgroup analysis for publication type, studies quality, and the continent that studies were conducted and meta-regression analysis for sample size, gender distribution, and data collection time as the independent variables. We conducted a leave-one-out sensitivity analysis to determine the influence of each study on the overall effect. This type of analysis performs sequent meta-analyses by leaving out exactly one study at each meta-analysis. In that case, we can investigate the way that each study affects the overall effect size estimate identifying influential studies. The Egger's test was used to assess the publication bias with a P-value <0.05 indicating publication bias. We did not perform meta-analysis for the factors related with intention of HCWs to accept COVID-19 vaccination since the data were highly heterogeneous and limited. We used OpenMeta[Analyst] for the meta-analysis.
| 3. Results|| |
3.1. Identification and selection of studies
Flowchart of the literature search according to PRISMA guidelines is presented in [Figure 1]. Initially, we identified 3 022 potential records through electronic databases and 730 duplicates were removed. After the screening of the titles and abstracts, we removed 2 114 records and we added one more record found by the reference lists scanning. Finally, we included 24 studies in this systematic review and meta-analysis that met our inclusion criteria.
|Figure 1: Flowchart of the literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis.|
Click here to view
3.2. Characteristics of the studies
Main characteristics of the 24 studies included in this review are presented in [Table 1]. A total of 50 940 HCWs were included in this systematic review with a minimum of 208 HCWs and a maximum of 12 034 HCWs among studies. Ten studies were conducted in Asia (China, Turkey, Kingdom of Saudi Arabia, Vietnam and Kuwait), six studies in North America (USA and Canada), four studies in Europe (France, Germany and Greece), three studies in Africa (Democratic Republic of the Congo, Eastern Cape and Zambia), and one study was multicenter (France, Belgium and Canada). More females were included in 19 studies, while more males participated in four studies. All studies were cross-sectional, while 23 studies used convenience sampling method and one used snowball sampling method. Nineteen studies were published in journals and five studies in pre-print services. One study did not report data regarding age, one regarding gender distribution, and 12 regarding response rate. Ten studies used a yes/no answer to assess intention of HCWs to accept COVID-19 vaccination, nine studies used a yes/no/uncertain answer, and five studies used Likert-type scales.
|Table 1: Main characteristics of the studies included in this systematic review.|
Click here to view
Intention of HCWs to accept vaccination and study population in the studies included in this systematic review are presented in [Table 2]. Percentage of participants willing to accept the vaccination ranged from 27.7% to 90.1%. Percentage of physicians that participated in studies ranged from 12.1% to 66.8%, while percentage of nurses ranged from 12.5% to 100%. Five studies did not report detailed data regarding study population.
|Table 2: Study population in the studies included in this systematic review.|
Click here to view
3.3. Quality assessment
Quality assessment of cross-sectional studies included in this review is shown in [Table 3]. Quality was moderate in six studies and good in 18 studies.
|Table 3: Quality of cross-sectional studies included in this systematic review.|
Click here to view
The overall proportion of HCWs that intended to accept COVID-19 vaccination was 63.5% (95% CI 56.5%-70.2%) [Figure 2]A. The heterogeneity between results was very high (I2=99.59%, P-value for the Hedges Q statistic <0.001). A leave-one-out sensitivity analysis showed that no single study had a disproportional effect on the pooled proportion, which varied between 62.1% (95% CI 55.3%- 68.7%), with Adeniyi et al. excluded, and 65.0% (95% CI 58.1%- 71.6%), with Nzaji et al. excluded [Supplementary Figure 1].
|Figure 2: Forest plot (A) and funnel plot (B) of the proportion of HCWs that intend to accept COVID-19 vaccination.|
Click here to view
According to subgroup analysis, the proportion of HCWs that intend to accept COVID-19 vaccination was higher for the studies that were published in journals [64.9% (95% CI 57.0%-72.4%), I2=99.66] than those in pre-print services [58.0% (95% CI 43.2%- 72.2%), I2=98.75]. Moreover, the proportion was almost the same for the studies with moderate quality [62.0% (95% CI 49.5%- 73.8%), I2=98.86] and those with good quality [64.0% (95% CI 55.4%-72.1%), I2=99.68]. The proportion of HCWs that intend to accept COVID-19 vaccination was higher in studies that were conducted in Europe [65.5% (95% CI 50.0%-79.6%), I2=99.22] and Asia [69.0% (95% CI 59.4%-77.9%), I2=98.84] compared to those in Africa [56.7% (95% CI 12.2%-95.2%), I2=99.77] and North America [(52.9% (95% CI 40.8%-64.9%), I2=99.78]. Meta-regression showed that the closer each study was performed to now, the more likely HCWs were to accept COVID-19 vaccination [coefficient=0.024, (95% CI 0.006-0.042), P=0.008]. Also, the proportion of HCWs that intend to accept COVID-19 vaccination was independent of the sample size (P=0.17), and gender distribution (P=0.15). P-value <0.05 for Egger's test and the funnel plot [Figure 2]B implied potential publication bias.
3.5. Factors related with intention of HCWs to accept COVID-19 vaccination
Twenty studies investigated factors related with intention of HCWs to accept COVID-19 vaccination, while 18 studies used multivariable analysis to control confounding [Table 4]. Statistically significant factors are presented in [Table 4] and were discussed in the following paragraphs.
|Table 4: Statistically significant factors related with intention of health care workers to accept COVID-19 vaccination.|
Click here to view
We found that several demographic characteristics were associated with COVID-19 vaccination acceptance. Profession was an important predictor since six studies found that physicians were more prone to get vaccinated against COVID-19 than other HCWs and especially nurses and paramedical staff. Male HCWs and white HCWs were more likely to be vaccinated. A great number of studies found that older age was associated with an increase in COVID-19 vaccine acceptance. Higher education level, increased outcome, and work in healthcare facilities in urban areas were related with increased COVID-19 vaccine acceptance. Also, HCWs with chronic conditions were more likely to be vaccinated against COVID-19.
Flu vaccination during previous season was associated with intention to accept COVID-19 vaccination. Stronger vaccine confidence and positive attitude towards a COVID-19 vaccine increased HCWs' willingness to get vaccinated against COVID-19. Fear about COVID-19, individual perceived risk about COVID-19, and weaker complacency about the COVID-19 were related with increased COVID-19 vaccination acceptance. Complacency was measured on a 7-point Likert scale (strongly disagree to strongly agree). HCWs exposed and in contact with suspected or confirmed COVID-19 patients and those with a previous COVID-19 infection were more likely to accept COVID-19 vaccine.
| 4. Discussion|| |
This systematic review and meta-analysis assessed the intention of HCWs to accept COVID-19 vaccination and related factors. Twenty-four papers met our inclusion criteria and the primary reasons that other papers were excluded from this review include irrelevant research question, study population other than HCWs, and other types of publications (e.g. qualitative studies, reviews, case reports, protocols, editorials, and letters to the editor). We found that the proportion of HCWs that intend to accept COVID-19 vaccination was moderate (63.5%) with a wide range among studies from 27.7% to 90.1%. This moderate level of acceptance may be attributable to several reasons, e.g. inadequate knowledge among HCWs regarding COVID-19,, negative attitude towards the disease,, and feelings of fear and anxiety during the COVID-19 pandemic,,,. Also, concerns raised for COVID-19 vaccination are related with inadequate knowledge about such new vaccines regarding the long term side effects, effectiveness, efficacy etc. Better knowledge of COVID-19 among HCWs affects their attitude, increases their confidence, and promotes preventive measures such as the vaccination,,. According to our subgroup analysis, the proportion of HCWs that intend to accept COVID-19 vaccination was higher in studies in Europe and Asia than those in North America and Africa. This finding is in accordance with a study in 10 countries in Africa, Latin America, Eastern Europe, Asia Pacific, and the Middle East where the influenza vaccination coverage rate in general population was much higher in Europe than in Asia and Africa. This difference may be attributable mainly to the fact that a national influenza vaccination policy and recommendations for seasonal influenza vaccination are standard in developed countries but this is not the case in many developing countries in Africa. Also, the availability of influenza vaccines is low in Africa, while the number of influenza vaccines per capita is much higher in high- income countries compared to lower and middle-income countries (median number: 139.2 vs. 6.1 per 1 000 population).
The positive effects of the influenza vaccine in health outcomes and in financial terms are well known,,,, but the vaccination rate is low even among HCWs. A meta-analysis with 45 studies in mainland China found that the influenza vaccination rate was 17.7%, 9.4%, 7.8%, and 3.5% for HCWs, general population, pregnant women, and people with chronic conditions, respectively. A similar finding was found in studies in Europe (United Kingdom, Germany, France, and Spain) where HCWs received influenza vaccination more often than the general population but in low levels, ranging from 15% to 29%. A meta-analysis included studies in Italy found that the proportion of influenza vaccination among nurses and ancillary workers was 13.47% and 12.52%, respectively. Influenza vaccination coverage is higher in the USA (80.6%) and Canada (ranging from 35.5% to 51.0%),, but still lower than the national Healthy People 2020 target of 90%.
We found a difference in intention to accept COVID-19 vaccination between the professions, with physicians most inclined to get vaccinated compared to other HCWs and especially nurses and paramedical staff. This finding is confirmed by two meta- analyses, including studies in Italy, where the prevalence of influenza vaccination among physicians was 23.18%, among nurses was 13.47%, and among ancillary workers was 12.52%. Several other studies,, worldwide confirm the fact that the influenza vaccination coverage among physicians is the highest. In general, physicians are more prone to accept vaccination than other HCWs, e.g. the full hepatitis B vaccination coverage among physicians is 2.6 times higher than nurses. Several reasons could be behind this observation such as greater misconceptions about vaccines among nurses and other HCWs, less fear and care about infectious diseases, less knowledge and more doubt about vaccine efficacy. This finding is a major concern in healthcare settings especially during the COVID-19 pandemic since nurses and assistant nurses have more and longer direct contact with patients than other HCWs. Also, the seroprevalence of SARS-CoV-2 antibodies is higher among front-line healthcare workers and healthcare assistants indicating that nurses and assistant nurses represent a high-risk group for SARS-CoV-2 infection.
We found that older age was related with an increase in willingness to get vaccinated against COVID-19. This finding is unsurprising since HCWs are quite familiar with the fact that older age is one of the strongest risk factors for COVID-19 mortality,,. Therefore, it is more probable for older HCWs to take the COVID-19 vaccine due to their own self-profit. In a similar way, we found that HCWs with chronic conditions were more prone to get vaccinated against COVID-19. This finding makes sense since HCWs with comorbidity is a high-risk group for complications and death from COVID-19 as this is the case for the general population also according to several meta-analyses,,,,. Older HCWs with comorbidity confront COVID-19 with fear and anxiety affecting critically their decision to accept a COVID-19 vaccine. An interesting result in our review is that male gender was associated with greater likelihood of taking COVID-19 vaccine. Two reviews regarding influenza vaccination and hepatitis B vaccination did not find any relation between gender and vaccination coverage. A possible explanation for our observation could be that the individual perceived risk about COVID-19 is higher among male HCWs.
According to our study, being vaccinated against flu during previous season was associated with COVID-19 vaccine acceptance. Similarly, HCWs with vaccine confidence and positive attitude towards a COVID-19 vaccine were more likely to be vaccinated against COVID-19. These findings are of utmost importance since the WHO named vaccine hesitancy as one of the top ten threats to global health in 2019. Healthcare workers especially at primary care should communicate in a clear way the message that vaccines are safe and effective to improve vaccination coverage in communities. Since a safe and effective COVID-19 vaccine seems to be the only solution for this pandemic, the positive attitude of HCWs towards vaccination is imperative. Vaccine hesitancy among HCWs with regard to other vaccines, such as seasonal influenza vaccine already exists,,. In case of the COVID-19 vaccine, the situation can be worse since vaccine hesitancy is fuelled by fake news and conspiracy theories. The reluctance or refusal of HCWs to vaccinate against COVID-19 could diminish the trust of individuals and trigger a ripple effect in the general public,. There is a need to build confidence and trust in communities to roll out a COVID-19 vaccine successfully.
Additionally, we found that individual perceived risk about COVID-19 was related with increased COVID-19 vaccination acceptance among HCWs. HCWs may be reluctant to receive a novel COVID-19 vaccine when they believe that it does not protect against a significant personal threat. On the other hand, the self- perceived susceptibility and seriousness of an infectious disease such as COVID-19 may increase vaccine acceptance. This association has already been observed in case of COVID-19 not only in the general public but also in HCWs. A warning sign to public health safety is that vaccine hesitancy is greater among nurses than among physicians,,.
Our study is subject to several limitations. In particular, more than the half of studies was of moderate quality, while four out of 24 studies were published in pre-print services which did not apply peer-review process. We performed subgroup analysis according to studies quality and publication type to overcome this limitation. The statistical heterogeneity in results was very high probably due to variability in study designs and populations. In that case, we applied a random effects model and we performed subgroup and meta-regression analysis. We included all studies conducted till to July 14, 2021 but vaccines are now available and HCWs attitudes towards COVID-19 vaccination could be changed for this reason. Our meta-regression analysis showed that the proportion of HCWs that intend to accept COVID-19 vaccination was independent of the data collection time but studies of current attitudes should be performed. Data with regards to the factors related with intention of HCWs to accept COVID-19 vaccination were limited, while five studies used multivariable models to eliminate confounding. We consider this as a potential area for future study. Moreover, all the studies included in this review were cross-sectional studies making causal inferences impossible. Finally, the proportion of HCWs that intend to accept COVID-19 vaccination may be an overestimation since studies evaluated self-reported answers that could be subject to social desirability bias, with HCWs knowing that the general public expects a high COVID-19 vaccination coverage among them.
In conclusion, HCWs are identified worldwide as priority recipients of the novel COVID-19 vaccine since they represent a high-risk group for SARS-CoV-2 infection and transmission risk of SARS- CoV-2 in clinical settings between patients and HCWs. Also, HCWs serve as trusted community workers on public health topics and their role in promoting COVID-19 vaccine acceptance is critical. Thus, COVID-19 vaccine hesitancy among HCWs should be eliminated to inspire the general public towards a positive attitude regarding a novel COVID-19 vaccine. We found a great variability of COVID-19 vaccination acceptance among HCWs worldwide and knowledge of the factors that influence this acceptance would be essential to provide information about vaccination programs, determine priority groups for vaccination, take extra protective measures, etc. Knowledge of the factors that affect intention of HWCs to accept COVID-19 vaccination is limited and there is an urgent need for further studies to make more valid inferences. Since vaccination is a complex behavior, understanding the way that HCWs take the decision to accept COVID-19 vaccination or not will give us the opportunity to develop the appropriate interventions to increase COVID-19 vaccination uptake and promote vaccination programs worldwide.
Conflict of interest statement
The authors declare that there are no conflicts of interest.
P.G, D.F. and D.K. were responsible for the conception and design of the study. P.G, I.V., D.F., A.B., and D.K. were responsible for the acquisition, analysis and interpretation of data. All the authors drafted the article or revised it critically for important intellectual content.
| References|| |
Cacciapaglia G, Cot C, Sannino F. Second wave COVID-19 pandemics in Europe: A temporal playbook. Sci Rep
Looi MK. Covid-19: Is a second wave hitting Europe? BMJ
World Health Organization. WHO coronavirus disease (COVID-19) Dashboard, 2021
. [Online]. Available from: https://covid19.who.int/
. [Accessed on 15 July 2021].
Poland GA, Tosh P, Jacobson RM. Requiring influenza vaccination for health care workers: Seven truths we must accept. Vaccine
(17- 18): 2251-2255.
National Advisory Committee on Immunization (NACI). Statement on influenza vaccination for the 2008-2009 season. An Advisory Committee Statement (ACS). Can Commun Dis Rep
Fiore AE, Uyeki TM, Broder K, Finelli L, Euler GL, Singleton JA, et al. Prevention and control of influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR
National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC). Use of influenza A (H1N1) 2009 monovalent vaccine: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep
Bonanni P, Boccalini S, Bechini A. The expected impact of new vaccines and vaccination policies. J Public Health
Bonanni P, Bonaccorsi G, Lorini C, Santomauro F, Tiscione E, Boccalini S, et al. Focusing on the implementation of 21st century vaccines for adults. Vaccine
Demicheli V, Jefferson T, Di Pietrantonj C, Ferroni E, Thorning S, Thomas RE, et al. Vaccines for preventing influenza in the elderly. Cochrane Database Syst Rev
Vasilevska M, Ku J, Fisman DN. Factors associated with healthcare worker acceptance of vaccination: A systematic review and meta- analysis. Infect Control Hosp Epidemiol
Prematunge C, Corace K, McCarthy A, Nair RC, Pugsley R, Garber G. Factors influencing pandemic influenza vaccination of healthcare workers-A systematic review. Vaccine
Sheldenkar A, Lim F, Yung CF, Lwin MO. Acceptance and uptake of influenza vaccines in Asia: A systematic review. Vaccine
Herzog R, Álvarez-Pasquin MJ, Díaz C, Del Barrio JL, Estrada JM, Gil Á. Are healthcare workers' intentions to vaccinate related to their knowledge, beliefs and attitudes? A systematic review. BMC Public Health
Auta A, Adewuyi EO, Kureh GT, Onoviran N, Adeloye D. Hepatitis B vaccination coverage among health-care workers in Africa: A systematic review and meta-analysis. Vaccine
Wang Q, Yue N, Zheng M, Wang D, Duan C, Yu X. Influenza vaccination coverage of population and the factors influencing influenza vaccination in mainland China: A meta-analysis. Vaccine
Moher D, Liberati A, Tetzlaff J, Altman DG, PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. PLoS Med
Rimal RN, Morrison D. A uniqueness to personal threat (UPT) hypothesis: How similarity affects perceptions of susceptibility and severity in risk assessment. Health Commun
Schimmenti A, Starcevic V. The four horsemen of fear: An integrated model of understanding fear experiences during the COVID-19 pandemic. Clin Neuropsychiatry
Yaqub O, Castle-Clarke S, Sevdalis N, Chataway J. Attitudes to vaccination: A critical review. Soc Sci Med
Santos WM dos, Secoli SR, Püschel VA de A. The Joanna Briggs Institute approach for systematic reviews. Rev Latino-Am Enfermagem
Barendregt JJ, Doi SA, Lee YY, Norman RE, Vos T. Meta-analysis of prevalence. J Epidemiol Community Health
Higgins JPT. Measuring inconsistency in meta-analyses. BMJ
Egger M, Smith GD, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ
Wallace BC, Schmid CH, Lau J, Trikalinos TA. Meta-analyst: Software for meta-analysis of binary, continuous and diagnostic data. BMC Med Res Methodol
Chawe A, Mfune RL, Syapiila P, Zimba SD, Vlahakis PA, Mwale S. Knowledge, attitudes and practices of COVID-19 among medical laboratory professionals in Zambia. Afr J Lab Med
Kuter BJ, Browne S, Momplaisir FM, Feemster KA, Shen AK, Green- McKenzie J, et al. Perspectives on the receipt of a COVID-19 vaccine: A survey of employees in two large hospitals in Philadelphia. Vaccine
Wang K, Wong ELY, Ho KF, Cheung AWL, Chan EYY, Yeoh EK, et al. Intention of nurses to accept coronavirus disease 2019 vaccination and change of intention to accept seasonal influenza vaccination during the coronavirus disease 2019 pandemic: A cross-sectional survey. Vaccine
Fu CX, Wei Z, Pei S, Li SP, Sun XH, Liu P. Acceptance and preference for COVID-19 vaccination in health-care workers (HCWs). medRxiv
2020. doi: 10.1101/2020.04.09.20060103.
Kwok KO, Li KK, Wei WI, Tang A, Wong S, Lee S. Are we ready when COVID-19 vaccine is available? Study on nurses' vaccine hesitancy in Hong Kong. medRxiv
2020. doi: 10.1101/2020.07.17.20156026.
Kose S, Mandiracioglu A, Sahin S, Kaynar T, Karbus O, Ozbel Y. Vaccine hesitancy of the COVID-19 by health care personnel. Int J Clin Pract
2020. doi: 10.1111/ijcp.13917.
Barry M, Temsah MH, Alhuzaimi A, Alamro N, Al-Eyadhy A, Aljamaan F, et al. COVID-19 vaccine confidence and hesitancy among healthcare workers: A cross-sectional survey from a MERS-CoV experienced nation. PLoS One
2021; 29; 16
Huynh G, Tran T, Nguyen HN, Pham LA. COVID-19 vaccination intention among healthcare workers in Vietnam. Asian Pac J Trop Med
Kaplan AK, Sahin MK, Parildar H, Adadan Guvenc I. The willingness to accept the COVID-19 vaccine and affecting factors among healthcare professionals: A cross-sectional study in Turkey. Int J Clin Pract
Qattan AMN, Alshareef N, Alsharqi O, Al Rahahleh N, Chirwa GC, Al- Hanawi MK. Acceptability of a COVID-19 vaccine among healthcare workers in the Kingdom of Saudi Arabia. Front Med (Lausanne)
Sun Y, Chen X, Cao M, Xiang T, Zhang J, Wang P, et al. Will healthcare workers accept a COVID-19 vaccine when it becomes available? A cross- sectional study in China. Front Public Health
Al-Sanafi M, Sallam M. Psychological determinants of COVID-19 vaccine acceptance among healthcare workers in Kuwait: A cross- sectional study using the 5C and vaccine conspiracy beliefs scales. Vaccines
Gadoth A, Halbrook M, Martin-Blais R, Gray A, Tobin NH, Ferbas KG, et al. Cross-sectional assessment of COVID-19 vaccine acceptance among health care workers in Los Angeles. Ann Intern Med
Shaw J, Stewart T, Anderson KB, Salmon DA, Ortiz C, Trief PM, et al. Assessment of U.S. health care personnel (HCP) attitudes towards COVID-19 vaccination in a large university health care system. Clin Infect Dis
2021. doi: 10.1093/cid/ciab731.
Unroe KT, Evans R, Weaver L, Rusyniak D, Blackburn J. Willingness of long-term care staff to receive a COVID-19 vaccine: A single state survey. J Am Geriatr Soc
Shekhar R, Sheikh AB, Upadhyay S, Singh M, Kottewar S, Mir H, et al. COVID-19 vaccine acceptance among health care workers in the United States. Vaccines (Basel)
Dzieciolowska S, Hamel D, Gadio S, Dionne M, Gagnon D, Robitaille L, et al. Covid-19 vaccine acceptance, hesitancy, and refusal among Canadian healthcare workers: A multicenter survey. Am J Infect Control
Gagneux-Brunon A, Detoc M, Bruel S, Tardy B, Rozaire O, Frappe P, et al. Intention to get vaccinations against COVID-19 in French healthcare workers during the first pandemic wave: A cross sectional survey. J Hosp Infect
Papagiannis D, Malli F, Raptis DG, Papathanasiou IV, Fradelos EC, Daniil Z, et al. Assessment of knowledge, attitudes, and practices towards new coronavirus (SARS-CoV-2) of health care professionals in Greece before the outbreak period. Int J Environ Res Public Health
Detoc M, Bruel S, Frappe P, Tardy B, Botelho-Nevers E, Gagneux- Brunon A. Intention to participate in a COVID-19 vaccine clinical trial and to get vaccinated against COVID-19 in France during the pandemic. Vaccine
Nohl A, Afflerbach C, Lurz C, Brune B, Ohmann T, Weichert V, et al. Acceptance of COVID-19 vaccination among front-line health care workers: A nationwide survey of emergency medical services personnel from Germany. Vaccines (Basel)
Nzaji MK, Ngombe LK, Mwamba GN, Ndala DB, Miema J, Lungoyo C, et al. Acceptability of vaccination against COVID-19 among healthcare workers in the Democratic Republic of the Congo. Pragmat Obs Res
Adeniyi OV, Stead D, Singata-Madliki M, Batting J, Wright M, Jelliman E, et al. Acceptance of COVID-19 vaccine among the healthcare workers in the Eastern Cape, South Africa: A cross sectional study. Vaccines
Verger P, Scronias D, Dauby N, Adedzi KA, Gobert C, Bergeat M, et al. Attitudes of healthcare workers towards COVID-19 vaccination: A survey in France and French-speaking parts of Belgium and Canada, 2020. Euro Surveill
Ghimire P, Dhungel S, Pokhrel A. Knowledge, attitude and practice of healthcare workers towards coronavirus disease 2019 (COVID-19) pandemic. J Nepal Health Res Counc
Limbu DK, Piryani RM, Sunny AK. Healthcare workers' knowledge, attitude and practices during the COVID-19 pandemic response in a tertiary care hospital of Nepal. PLoS One
Apisarnthanarak A, Apisarnthanarak P, Siripraparat C, Saengaram P, Leeprechanon N, Weber DJ. Impact of anxiety and fear for COVID-19 toward infection control practices among Thai healthcare workers. Infect Control Hosp Epidemiol
Lu W, Wang H, Lin Y, Li L. Psychological status of medical workforce during the COVID-19 pandemic: A cross-sectional study. Psychiatry Res
Lima CKT, Carvalho PM de M, Lima I de AAS, Nunes JVAO, Saraiva JS, de Souza RI, et al. The emotional impact of coronavirus 2019-nCoV (new coronavirus disease). Psychiatry Res
García-Reyna B, Castillo-García GD, Barbosa-Camacho FJ, Cervantes- Cardona GA, Cervantes-Pérez E, Torres-Mendoza BM, et al. Fear of COVID-19 scale for hospital staff in regional hospitals in Mexico: A brief report. Int J Ment Health Addict
Zhang M, Zhou M, Tang F, Wang Y, Nie H, Zhang L, et al. Knowledge, attitude, and practice regarding COVID-19 among healthcare workers in Henan, China. J Hosp Infect
McEachan R, Taylor N, Harrison R, Lawton R, Gardner P, Conner M. Meta-analysis of the reasoned action approach (RAA) to understanding health behaviors. Ann Behav Med
Huynh G, Nguyen T, Tran V, Vo KN, Vo VT, Pham LA. Knowledge and attitude toward COVID-19 among healthcare workers at District 2 Hospital, Ho Chi Minh City. Asian Pac J Trop Med
de Lataillade C, Auvergne S, Delannoy I. 2005 and 2006 seasonal influenza vaccination coverage rates in 10 countries in Africa, Asia Pacific, Europe, Latin America and the Middle East. J Public Health Pol
Duque J, McMorrow ML, Cohen AL. Influenza vaccines and influenza antiviral drugs in Africa: Are they available and do guidelines for their use exist? BMC Public Health
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
Imai C, Toizumi M, Hall L, Lambert S, Halton K, Merollini K. A systematic review and meta-analysis of the direct epidemiological and economic effects of seasonal influenza vaccination on healthcare workers. PLoS One
Kliner M, Keenan A, Sinclair D, Ghebrehewet S, Garner P. Influenza vaccination for healthcare workers in the UK: Appraisal of systematic reviews and policy options. BMJ Open
Dolan GP, Harris RC, Clarkson M, Sokal R, Morgan G, Mukaigawara M, et al. Vaccination of healthcare workers to protect patients at increased risk of acute respiratory disease: Summary of a systematic review. Influenza Other Respir Viruses
Blank PR, Schwenkglenks M, Szucs TD. Influenza vaccination coverage rates in five European countries during season 2006/07 and trends over six consecutive seasons. BMC Public Health
La Torre G, Mannocci A, Ursillo P, Bontempi C, Firenze A, Panico MG, et al. Prevalence of influenza vaccination among nurses and ancillary workers in Italy: Systematic review and meta analysis. Hum Vaccin
Baron G, De Wals P, Milord F. Vaccination practices of Quebec family physicians. Influenza vaccination status and professional practices for influenza vaccination. Can Fam Physician
Lester RT, McGeer A, Tomlinson G, Detsky AS. Use of, effectiveness of, and attitudes regarding influenza vaccine among house staff. Infect Control Hosp Epidemiol
Mannocci A, Ursillo P, Bontempi C, Sferrazza A, La Torre G. Prevalence of influenza vaccination among physicians and related enhancing and preventing factors in Italy. Rev Health Care
Lu P, O’Halloran AC, Ding H, Williams WW, Black CL. Influenza Vaccination of healthcare personnel by work setting and occupation-U. S., 2014. Am J Prev Med
Reda Alenazi B, Mohamed Hammad S, Elwan Mohamed A. Prevalence of seasonal influenza vaccination among primary healthcare workers in Arar city, Saudi Arabia. Electron Physician
Jiang L, Ng HL, Ho HJ, Leo YS, Prem K, Cook AR, et al. Contacts of healthcare workers, patients and visitors in general wards in Singapore. Epidemiol Infect
Galanis P, Vraka I, Fragkou D, Bilali A, Kaitelidou D. Seroprevalence of SARS-CoV-2 antibodies and associated factors in health care workers: A systematic review and meta-analysis. J Hosp Infect
Yanez ND, Weiss NS, Romand JA, Treggiari MM. COVID-19 mortality risk for older men and women. BMC Public Health
Mehraeen E, Karimi A, Barzegary A, Vahedi F, Afsahi AM, Dadras O, et al. Predictors of mortality in patients with COVID-19-A systematic review. Eur J Integr Med
Sepandi M, Taghdir M, Alimohamadi Y, Afrashteh S, Hosamirudsari H. Factors associated with mortality in COVID-19 patients: A systematic review and meta-analysis. Iran J Public Health
Mesas AE, Cavero-Redondo I, Álvarez-Bueno C, Sarriá Cabrera MA, Maffei de Andrade S, Sequí-Dominguez I, et al. Predictors of in-hospital COVID-19 mortality: A comprehensive systematic review and meta- analysis exploring differences by age, sex and health conditions. PLoS One
Miller LE, Bhattacharyya R, Miller AL. Diabetes mellitus increases the risk of hospital mortality in patients with Covid-19: Systematic review with meta-analysis. Medicine (Baltimore)
Yu JN, Wu BB, Yang J, Lei XL, Shen WQ. Cardio-cerebrovascular disease is associated with severity and mortality of COVID-19: A systematic review and meta-analysis. Biol Res Nurs
Geoghegan S, O'Callaghan KP, Offit PA. Vaccine safety: Myths and misinformation. Front Microbiol
Wilson R, Zaytseva A, Bocquier A, Nokri A, Fressard L, Chamboredon P, et al. Vaccine hesitancy and self-vaccination behaviors among nurses in southeastern France. Vaccine
Lau LHW, Lee SS, Wong NS. The continuum of influenza vaccine hesitancy among nursing professionals in Hong Kong. Vaccine
Di Martino G, Di Giovanni P, Di Girolamo A, Scampoli P, Cedrone F, D'Addezio M, et al. Knowledge and attitude towards vaccination among healthcare workers: A multicenter cross-sectional study in a Southern Italian Region. Vaccines
Puri N, Coomes EA, Haghbayan H, Gunaratne K. Social media and vaccine hesitancy: New updates for the era of COVID-19 and globalized infectious diseases. Hum Vaccin Immunother
MacDonald NE, Dubé E. Unpacking vaccine hesitancy among healthcare providers. EBioMedicine
Opel DJ, Heritage J, Taylor JA, Mangione-Smith R, Salas HS, Devere V, et al. The architecture of provider-parent vaccine discussions at health supervision visits. Pediatrics
Dubé E, Laberge C, Guay M, Bramadat P, Roy R, Bettinger J. Vaccine hesitancy: An overview. Hum Vaccin Immunother
Malik AA, McFadden SM, Elharake J, Omer SB. Determinants of COVID-19 vaccine acceptance in the US. EClinicalMedicine
Hollmeyer HG, Hayden F, Poland G, Buchholz U. Influenza vaccination of health care workers in hospitals-A review of studies on attitudes and predictors. Vaccine
Keske Ş, Mutters NT, Tsioutis C, Ergönül Ö. EUCIC influenza vaccination survey team. Influenza vaccination among infection control teams: A EUCIC survey prior to COVID-19 pandemic. Vaccine
Pless A, McLennan SR, Nicca D, Shaw DM, Elger BS. Reasons why nurses decline influenza vaccination: A qualitative study. BMC Nurs
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]