
==== Front
Hum Vaccin Immunother
Hum Vaccin Immunother
Human Vaccines & Immunotherapeutics
2164-5515
2164-554X
Taylor & Francis

39279572
10.1080/21645515.2024.2402116
2402116
Version of Record
Research Article
Influenza
Coverage of influenza vaccination and influencing factors among healthcare workers in Shandong Province, China, 2021–2022
Y. LIU ET AL.
HUMAN VACCINES & IMMUNOTHERAPEUTICS
Liu Yuwei a
Liu Ti b
Yao Mingxiao b
Wang Qiang a
Li Renpeng c
Kou Zengqiang b
a College of Public Health, Shandong Second Medical University , Shandong, China
b Shandong Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Prevention and Control , Jinan, China
c Shandong Provincial Center for Health Science & Technology and Talents Development , Shandong, China
CONTACT Renpeng Li rpleesd@163.com Shandong Provincial Center for Health Science & Technology and Talents Development, No.11, Yandong New Road, Jinan, Shandong 250014, P.R. China.
Zengqiang Kou jack-cou@163.com Shandong Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Prevention and Control, No. 16992 Jingshi Road, Jinan, Shandong 250014, P.R. China.
16 9 2024
2024
16 9 2024
20 1 2402116Integra13 9 2024
Integra13 9 2024
29 5 2024
22 8 2024
04 9 2024
© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.
2024
The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

ABSTRACT

Healthcare workers (HCWs) are at increased risk of exposure to the influenza virus in their daily clinical and disease prevention activities, making them a high-risk group for influenza infection. However, the vaccination rate among HCWs has always been low. This study investigated influenza vaccination uptake and willingness among HCWs in the context of the COVID-19 pandemic. The analysis revealed that the influenza vaccination uptake among HCWs was 67.5%, with 79.6% willing to receive the influenza vaccine in 2022/2023 A significant majority (92.7%) agreed that the COVID-19 pandemic increased their willingness to receive the influenza vaccine, and 94.8% agreed with the necessity of receiving the influenza vaccine even after COVID-19 vaccination. Binary logistic regression model identified key factors that influence vaccination intentions. HCWs who perceived a high risk of influenza and its threat to health, found vaccination convenient, and believed in the safety of the influenza vaccine were more likely to be vaccinated. Conversely, the high price of the influenza vaccine was a barrier, whereas those who considered the vaccine affordable were more likely to be vaccinated. Although Changchun Changsheng vaccine incident (The Changchun Changsheng Biotechnology Company was found to have violated good manufacturing practices in 2018, leading to widespread distribution of subpotent vaccines in China.) may not significantly impact the vaccination uptake among healthcare workers, some HCWs still harbor doubts about vaccine safety, which remains a key reason for vaccine hesitancy. This study emphasizes the importance of the strict monitoring and management of vaccines, conducting clinical studies to support vaccine safety, and implementing free influenza vaccine policies, workplace vaccination requirements, and organized mass vaccinations. Educational efforts to increase HCWs’ understanding of influenza and influenza vaccines are crucial to increasing vaccination uptake. Furthermore, implementing comprehensive intervention measures is essential to effectively improve the influenza vaccination uptake.

KEYWORDS

Influenza
influenza vaccination
healthcare workers
Shandong Provincial Natural Science Foundation 10.13039/501100007129 ZR2020MH338 This work has been supported by Shandong Provincial Natural Science Foundation, (ZR2020MH338 and ZR2021MH372).
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pmcIntroduction

Seasonal influenza, an acute respiratory infectious disease caused by the influenza virus, is classified as a Class C communicable disease in China, and represents the lowest tier of management among statutory infectious diseases.1 However, the prevalence of seasonal influenza can lead to significant morbidity, mortality, and economic costs.2,3 Globally, between 291,243 and 645,832 individuals are estimated to die annually from respiratory-related illnesses.2 In China, the incidence rate of influenza in 2018 was 5.51 per 100,000 people, and in 2019, the disease burden amounted to a substantial economic cost of 26.38 billion yuan ($3.819 billion), with hospitalization-related expenses accounting for 86.4% of this figure.4,5

Vaccines are often regarded as one of the greatest innovations in medical history, significantly reducing the incidence and mortality rates of life-threatening diseases.6 Annual influenza vaccination is an effective means of preventing influenza and reducing the risk of associated complications.7–9 In China, the influenza vaccine is categorized as a non-immunization program vaccine, and residents are vaccinated on a voluntary basis.10 However, healthcare workers (HCWs), due to occupational factors, are at a higher risk of exposure to the influenza virus in their daily clinical and disease prevention activities, making them a high-risk group for influenza infection.11 The World Health Organization (WHO) has identified HCWs as a priority group for seasonal influenza vaccination.12 According to data from the European Centre for Disease Prevention and Control (ECDC), vaccination rates among HCWs in Europe are generally low.13 A meta-analysis revealed that among all unvaccinated individuals with influenza, the incidence rate of influenza among HCWs was 18.7%.14

Currently, the influenza vaccination rate among HCWs in China remains low, with significant disparities observed across different regions and work environments.15 During the 2018–2019 period, the influenza vaccination rate among Chinese HCWs was 11.6%.16 China has made considerable efforts to promote influenza vaccination among HCWs, resulting in a notable increase to 67.0% during the 2019–2020 flu season. This improvement may be attributed to the official directive issued by the Chinese National Health Commission in 2018/2019, which mandated that medical institutions provide free influenza vaccinations to their staff.17 A survey indicated that the vaccination rate for the 2020/2021 flu season was 43.7%, which may have been lower because COVID-19 vaccinations were prioritized, thereby reducing the accessibility of influenza vaccines.18 Given the potential impact of the COVID-19 pandemic on public awareness of infectious disease prevention and health behaviors, investigating whether this situation has influenced influenza vaccination rates and vaccine acceptance is essential. Additionally, exploring HCWs’ motivations and barriers related to influenza and influenza vaccination can contribute to enhancing vaccination rates among this critical group.

Shandong, situated on the eastern coast of China, is one of the country’s most populous provinces with approximately 101.5 million residents.19 Economically, Shandong ranks among China’s strongest provinces, with growth and urbanization rates comparable to those of Guangdong and Jiangsu.20 Investigating health trends in Shandong, Given its large and diverse population, investigating health trends in Shandong can provide valuable insights for the formulation of national health policies.

This study aimed to investigate the coverage and factors associated with receiving influenza vaccinations among healthcare workers in 2021/2022 in Shandong Province. Furthermore, we aimed to gain insights into HCWs’ suggestions for enhancing vaccination rates, with the aim of providing a reference for promoting influenza vaccination among this group.

Methods

Study design

An internet-based cross-sectional study was conducted on the WeChat platform from September 2021 to February 2022. To ensure the representativeness of the study results, a stratified random sampling method was employed to select healthcare workers, encompassing various professionals engaged in medical and health services. The study included four groups – clinicians, nurses, laboratory technicians, and others – from Jinan and Weifang cities in Shandong Province as survey subjects. Jinan, the capital of Shandong Province, boasts abundant and concentrated medical resources, along with well-developed public health infrastructure that includes, numerous large hospitals and research institutions. Weifang, located in central Shandong Province, has a more balanced distribution of medical resources, covering both urban areas and surrounding rural areas. Jinan and Weifang are representative in various aspects and this representation enhances the external validity of the research findings, allowing them to be generalized to the entire province. In each city, at least one tertiary hospital, two secondary hospitals, ten township health centers or community health service centers, and one municipal and two to three county-level disease prevention and control centers were selected as the survey units. The survey was carried out among the HCWs of these units. Based on our preliminary research, a survey questionnaire was designed by experts in the field of flu, covering five main aspects: (1) Basic information of HCWs, including gender, age, educational level, department, and job category. (2) Self-reported influenza vaccination status for the 2021/2022 season and vaccination willingness for the 2022/2023 season. (3) Factors affecting influenza vaccination uptake. (4) Reasons for HCWs’ willingness or unwillingness to receive vaccinations. (5) Survey of HCWs’ suggestions for improving vaccination uptake.

The following sample size calculation formula for cross-sectional studies was used to estimate the required sample size:Nmin=deff×Z1−α/22×p×1−pd2

To reach the estimates of coverage at the significance level of a two-tailed a error of 5% and a permissible error (d) of 0.01,an 11.6% (to get the largest sample size) was used because this number was the local influenza vaccination rate from the 2018–2019 influenza season,9 and the design effect (deff) was 3. The minimum target sample size was calculated to be 10,371.

Data collection and statistical analysis

A questionnaire link was disseminated via the WeChat platform. For certain questions, respondents had the option to select multiple answers. The questionnaire was distributed using the survey design program Questionnaire Star (wjx.cn). The participants were asked to log in with a unique username and password or to use other forms of authentication to verify their identity before they can complete the survey. Prior to the survey, all participants who agreed to partake in the study signed an informed consent form. Data from the subjects were de-identified to protect patient privacy. Microsoft Office Excel 2016 was utilized for data organization and bar chart, and SPSS 26.0 was employed for statistical analysis of the 2021/2022 influenza vaccination uptake and willingness to vaccinate rate, which was calculated as follows: influenza vaccination rate (%) = (Number of individuals vaccinated in 2021/2022)/(Total number of survey respondents) ×100%. Willingness to vaccinate rate (%) = (Number of individuals willing to vaccinate in 2022/2023)/(Total number of survey respondents) × 100%. Factors that influence influenza vaccination uptake and willingness to vaccinate were initially analyzed using chi-square tests (α = 0.05). The odds ratio (OR) and 95% CI were used to explore the influencing factors of influenza willingness, using binary logistics regression analysis and multinomial logistic regression analysis. In this analysis, the answer options were “yes” and “no” to whether to get the flu vaccine in 2021/2022 and willingness to receive the vaccine in 2022/2023 and we combined the responses “no” and “unclear” into “no” to help reduce ambiguity in the data, thereby enhancing the clarity and interpretability of the analysis. In the investigation into the reasons for vaccine acceptance, our questionnaire consisted of nine items assessed using a 5-point Likert scale (e.g., strongly agree, agree, not sure, disagree, or strongly disagree). The questionnaire took less than 15 minutes to complete in the pretest. Analyses were performed using SPSS version 26, R software version 4.3.3 and the Likert packages.

Quality control

The research plan and survey questionnaire were designed by experts in the field of infectious diseases from the Shandong Center for Disease Control and Prevention. The questionnaire was discussed and revised by experts until an agreement was reached. Prior to the formal survey, a pilot test of the questionnaire was conducted to identify and address potential issues. Based on the feedback of this pilot, experts made any necessary revisions and improvements. The survey was distributed via an online link with a restricted completion date. The investigators underwent uniform training, and their task was to liaise with other survey units within the local city. After the survey concluded, the basic information of the subjects from each survey unit was verified. Questionnaires with at least three missing answers, missing key details, or logical errors were excluded. The survey was conducted in Chinese, and targeted participants who are native Chinese speakers. All data analysis processes were conducted in Chinese to ensure accuracy and consistency. The results were translated from Chinese to English by professional translators to ensure accuracy and professionalism. The analysis included valid survey respondents with complete basic information, as well as data on influenza vaccination uptakes during the 2021/2022 flu season among hospital workers.

Results

Demographics of the study population

A total of 13,966 questionnaires were received in this survey. After 588 invalid questionnaires (4.2%) were filtered out 13,378 participants (95.8%) remained. Furthermore, 393 participants (2.8%) completed the survey in less than 60 seconds. The valid response rate was 93.0%.

Among the effective survey population, 57.2% of the HCWs were from Jinan city, whereas 42.8% were from Weifang city. The majority of the respondents held a bachelor’s degree, totaling 8537 individuals (65.8%).The employment distribution was as follows: 4883 individuals (37.6%) worked in tertiary hospitals, 3657 individuals (28.2%) in secondary hospitals, 3926 individuals (30.2%) worked in community and township health centers, and 519 individuals (30.0%) worked in disease control centers. With respect to departmental distribution, 1326 individuals (10.2%) worked in high-risk departments 10,122 individuals (7.8%) worked in public health departments, and 10,647 individuals (82.0%) worked in other departments. The professional breakdown included 3778 clinical doctors (29.1%), 5395 nurses (41.6%), 431 laboratory technicians (3.3%), and 3381 individuals (26.0%) in other categories. A total of 22.8% of the respondents had contracted influenza in the past two years. Within the surveyed hospitals, 7468 individuals (57.5%) were required by their employers to receive the influenza vaccine 10,430 individuals (80.3%) were offered the vaccine free of charge, and 10,606 individuals (81.7%) in their work units who organized centralized vaccination

Influenza vaccination coverage among HCWs and associated factors

The influenza vaccination uptake among HCWs was 67.5% (8761/12985), with 10,330 individuals expressing willingness to receive the vaccine in 2022/2023, accounting for 79.6% of respondents (10330/12985). A chi-square test was used to examine the differences in vaccine uptake across various characteristics such as age, education, years of service, institutional level, department, and job category. The results revealed significant differences across all surveyed characteristics (p < .001) (Table 1). Table 1. Demographic and other characteristics of the participants.

Characteristics	Total n (%)	Vaccinated (%)	X2	p	
totality	12985(100.0)	8761(67.5)	 	 	
Gender	 	 	21.346	<.001	
Man	3351(25.8)	2153(64.2)	 	 	
Woman	9634(74.2)	6608(68.6)	 	 	
Age	 	 	215.616	<.001	
<35	5926(45.7)	3608(60.9)	 	 	
35-45	4120(31.7)	3016(73.2)	 	 	
>45	2939(22.6)	2137(72.7)	 	 	
Nation	 	 	2.495	.114	
Han nationality	12893(99.3)	8709(67.5)	 	 	
Other	92(0.7)	55(59.8)	 	 	
Education	 	 	133.365	<.001	
Technical secondary school	946(7.3)	594(62.8)	 	 	
Junior college	2277(17.5)	1368(60.1)	 	 	
Undergraduate course	8537(65.8)	6050(70.9)	 	 	
Postgraduate and above	1225(9.4)	749(61.1)	 	 	
Years of working	 	 	289.803	<.001	
<5	3012(23.2)	1680(55.8)	 	 	
5-9	3132(24.1)	2080(66.4)	 	 	
10-15	2178(16.8)	1569(72.0)	 	 	
>15	4663(35.9)	3432(73.6)	 	 	
Unit level	 	 	179.129	<.001	
Tertiary hospital	4883(37.6)	3481(71.3)	 	 	
Secondary hospital	3657(28.2)	2153(58.9)	 	 	
Community and township	3926(30.2)	2788(71.0)	 	 	
Health centers	519(4.0)	339(65.3)	 	 	
Departmenta	 	 	45.200	<.001	
High-risk department	1326(10.2)	949(71.6)	 	 	
Public health department	1012(7.8)	761(75.2)	 	 	
Others	10647(82.0)	7051(66.2)	 	 	
Categoryb	 	 	20.274	<.001	
Clinician	3778(29.1)	2414(63.9)	 	 	
Nurse	5395(41.6)	3744(69.4)	 	 	
Laboratory technician	431(3.3)	282(65.4)	 	 	
Others	3381(26.0)	2321(68.6)	 	 	
Contracted influenza in the past two years	 	 	125.501	<.001	
Yes	2953(22.8)	2243(76.0)	 	 	
No	8626(66.4)	5609(65.2)	 	 	
Unclear	1406(10.8)	909(64.7)	 	 	
Vaccination requirements for HCWs’ locations	 	 	2197.067	<.001	
Required	7468(57.5)	6056(81.1)	 	 	
Not required but encouraged	4200(32.3)	2453(58.4)	 	 	
Neither required nor encouraged	502(3.9)	117(23.3)	 	 	
Unclear	815(6.3)	135(16.6)	 	 	
Whether to provide free vaccination for employees	 	 	2769.529	<.001	
Yes	10430(80.3)	8146(78.1)	 	 	
No	1594(12.3)	456(28.6)	 	 	
Unclear	961(7.4)	159(16.5)	 	 	
Whether to organize centralized vaccination	 	 	3103.531	<.001	
Yes	10606(81.7)	8306(78.3)	 	 	
No	1419(10.9)	287(20.2)	 	 	
Unclear	960(7.4)	168(17.5)	 	 	
Have you conducted any previous influenza-related publicity or training	 	 	654.411	<.001	
Yes	11658(89.8)	8279(71.0)	 	 	
No	486(3.7)	185(38.1)	 	 	
Unclear	841(6.5)	297(35.3)	 	 	
a “high-risk departments” included respiratory, infectious diseases, emergency, intensive care unit/intensive medicine and fever clinic. “other departments” included the remaining departments.

b “Laboratory technicians” included inspection, imaging, ultrasound, electrocardiogram, pharmacy, etc. “others” included the remaining category.

Table 2. Binary logistic regression analysis of vaccination uptake.

Characteristics	B	Wald	OR 95%Cl	
Gender (Woman)	 	 	1	
Man	−0.19	11.81	00.83(0.74-0.92)*	
Age (>45)	 	 	1	
<35	−0.72	116.69	0.49(0.43-0.56)**	
35-45	−0.18	6.46	0.84(0.73-0.96)*	
Education (Postgraduate and above)	 	 	1	
Technical secondary school	0.06	0.18	1.06(0.82-1.36)	
Junior college	0.06	0.28	1.06(0.86-1.29)	
Undergraduate course	0.36	18.26	1.43(1.21-1.68)**	
Unit level (Health centers)	 	 	1	
Tertiary hospital	−0.40	9.27	0.67(0.52-0.87)*	
Secondary hospital	−0.43	10.30	0.65(0.50-0.85)**	
Community hospitals and township health centers	0.17	1.61	1.19(0.91-1.55)	
Department (Others)	 	 	1	
High-risk department	0.16	4.66	1.18(1.02-1.37)*	
Public health department	0.24	5.80	1.30(1.05-1.54) *	
Category (Others technician)	 	 	1	
Clinician	−0.25	14.03	0.78(0.68-0.89)**	
Nurse	−0.13	4.10	0.88(0.77-1.00)*	
Laboratory technician	−0.05	0.14	0.95(0.73-1.24)	
Contracted influenza in the past two years (NO)	 	 	1	
Yes	0.51	78.66	1.66(1.49-1.86)**	
Vaccination requirements for HCWs’ locations (Unclear)	 	 	1	
Required	1.45	153.91	4.27(3.39-5.37)**	
Not required but encouraged	0.83	51.07	2.29(1.82-2.87)**	
Neither required nor encouraged	0.17	1.11	1.19(0.86-1.63)	
Whether to provide free vaccination for employees (No)	 	 	1	
Yes	0.90	83.77	2.45(2.02-2.97)**	
Whether to organize centralized vaccination (No)	 	 	1	
Yes	1.542	232.96	4.67(3.83-5.69)**	
Have you conducted any previous influenza-related publicity or training (No)	 	 	1	
Yes	0.23	7.92	1.25(1.07-1.48)*	
*p < .05; **p < .001.

*The reference categories are in parentheses.

When these factors were incorporated into a binary logistic regression model, the results revealed that women were more likely to get the flu vaccine than men; moreover, individuals aged over 45 years were more likely to get the vaccine. The likelihood of receiving vaccinations was significantly lower among postgraduates compared to individuals with other degrees. HCWs in health centers were more likely to be vaccinated compared to those in tertiary and secondary hospitals. HCWs in high-risk departments (OR = 1.18, 95% CI = 1.02-1.37, p < .05) and public health departments (OR = 1.30, 95% CI = 1.05-1.54, p < .05) were more likely to be vaccinated compared to those in other departments. Clinicians (OR = 0.78, 95% CI = 0.68-0.89, p < .001) and nurses (OR = 0.88, 95% CI = 0.77-1.00, p < .05) had lower vaccination uptake compared to other technicians. HCWs who had experienced influenza in the past two years or were unaware of having had it were more likely to be vaccinated than those who had not been infected. Furthermore, vaccination uptake was greater among individuals whose institutions mandate vaccination and provide it free of charge. (Table 2).

Factors affecting influenza vaccination uptake

In our survey assessing the attitudes of 12,985 public health workers toward vaccination uptake using a five-point Likert scale, we found that the majority of HCWs had a positive attitude toward influenza vaccination. A total of 92.7% agreed that the COVID-19 pandemic has increased their willingness to receive the influenza vaccine, whereas 94.8% agreed that it is necessary to receive the influenza vaccine even after being vaccinated for COVID-19. A total of 51.7% agreed that they were likely to get flu, and 66.4% thought that influenza was a major health threat. Additionally, 55.5% agreed that vaccine incident have an impact on their confidence in vaccines (Figure 1). Figure 1. Survey of reasons for vaccine acceptance on the five-level likert scale.

The logistic regression model was constructed using whether or not to vaccinated as the dependent variables and eight factors that were significant in the univariate analysis as the independent variables (Table 3). The results indicated that those who strongly agreed that they had a high probability of getting influenza and that influenza posed a great threat to their health were more likely to receive the influenza vaccine. HCWs who strongly agreed that it is convenient to get vaccinated and the flu vaccine is safe were more likely to get vaccinated. The high price of the flu vaccine was a barrier to vaccination intentions, and those who agreed (OR = 1.46, 95% CI = 1.20-1.78, p < .001) that the vaccine was cheap were more likely to be vaccinated. Respondents who strongly disagreed (OR = 1.58, 95% CI = 1.20-2.08, p < .05) or disagree (OR = 1.45, 95% CI = 1.17-1.80), p < .05) that vaccine incidents significantly impact their confidence in vaccines had significantly higher vaccination uptake than those who strongly agreed. Moreover, those who strongly agreed that the COVID-19 pandemic has increased their willingness to get a flu vaccine and those who believed that it is necessary to get a flu vaccine after the COVID-19 are more likely to be vaccinated. Table 3. Logistic regression of reasons for vaccine acceptance.

 	X2	p	B	Wald	OR (95% Cl)	
I have a high risk of catching the flu=1	978.483	<.001	−0.944	38.277	0.38(0.29-0.52)**	
2	 	 	−0.994	54.934	0.37(0.29-0.48)**	
3	 	 	−0.589	21.996	0.56(0.43-0.71)**	
4	 	 	−0.245	3.648	0.78(0.61-1.01	
5	 	 	 	 	1	
The flu poses a serious threat to my health=1	1143.292	<.001	−0.939	32.578	0.39(0.28-0.54)**	
2	 	 	−0.788	36.866	0.46(0.35-0.59)**	
3	 	 	−0.474	15.322	0.62(0.49-0.79)**	
4	 	 	−0.052	0.202	0.95(0.76-1.19)	
5	 	 	 	 	1	
The flu vaccine is a necessary measure to prevent the flu=1	1355.348	<.001	−0.363	2.131	0.70(0.43-1.13)	
2	 	 	−1.104	49.574	0.33(0.24-0.45)**	
3	 	 	−0.441	16.084	0.64(0.52-0.80)**	
4	 	 	−0.187	4.971	0.83(0.70-0.98)*	
5	 	 	 	 	1	
The flu vaccine is safe=1	1143.186	<.001	0.796	5.271	2.23(1.12-4.37)	
2	 	 	−0.462	2.586	0.63(0.36-1.11)	
3	 	 	−0.882	57.928	0.41(0.33-0.52)**	
4	 	 	−0.277	7.963	0.76(0.63-0.92)*	
5	 	 	 	 	1	
The vaccine incident has a great impact on my confidence in vaccines=1	590.853	<.001	0.457	10.764	1.58(1.20-2.08)*	
2	 	 	0.371	11.252	1.45(1.17-1.80)*	
3	 	 	0.075	0.478	1.08(0.87-1.33)	
4	 	 	0.016	0.023	1.02(0.82-1.25)	
5	 	 	 	 	1	
It’s convenient for me to get the flu vaccine=1	1379.310	<.001	−0.113	0.172	0.89(0.52-1.52)	
2	 	 	−1.215	55.936	0.30(0.22-0.41)**	
3	 	 	−1.253	110.766	0.29(0.23-0.36)**	
4	 	 	−0.356	15.003	0.70(0.59-0.84)**	
5	 	 	 	 	1	
I think the price of the flu vaccine is very cheap=1	671.163	<.001	−0.461	9.982	0.63(0.47-0.84)**	
2	 	 	−0.072	0.426	0.93(0.75-1.15)	
3	 	 	0.007	0.004	1.01(0.82-1.23	
4	 	 	0.381	14.378	1.46(1.20-1.78)**	
5	 	 	 	 	1	
The COVID-19 has increased my willingness to get the flu vaccine=1	1307.024	<.001	−1.079	4.247	0.34(0.12-0.95)*	
2	 	 	−1.122	31.105	0.33(0.22-0.48)**	
3	 	 	−1.186	90.6	0.31(0.24-0.39)**	
4	 	 	−0.321	12.038	0.73(0.61-0.87)**	
5	 	 	 	 	1	
It’s still necessary to get the flu vaccine after getting the COVID-19 vaccine=1	1241.700	<.001	−0.166	0.114	0.85(0.32-2.22)	
2	 	 	−0.93	10.809	0.39(0.23-0.69)*	
3	 	 	−0.925	54.231	0.340(0.31-0.51)**	
4	 	 	−0.342	18.464	0.71(0.61-0.83)**	
5	 	 	 	 	1	
*1 = Strongly disagree, 2 = Disagree, 3 = Unsure, 4 = Agree, 5 = Strongly agree (reference category).

*p < .05; **p < .001.

Reasons for HCWs’ willingness or unwillingness to receive vaccinations

The study also assessed the reasons behind participants’ willingness or unwillingness to receive vaccinations. According to the data, the primary reason participants were willing to receive the influenza vaccine was that they believed it would help prevent a major flu outbreak (7450/10330, 72.1%). The second and third reasons, namely recommendations from national decision-making organization (National Health Commission of the People’s Republic of China (NHC)) (6653/10330, 64.4%), and the requirements of affiliated hospitals (6524/10330, 63.2%), had similar percentages. The least recognized reason among participants was to prevent/reduce absenteeism (3563/10330, 34.5%), followed by colleagues receiving the vaccine (3599/10330, 34.8%) (Figure 2a). Figure 2. Reasons for vaccine willingness (a) and unwillingness (b).

Furthermore, 2655 (20.5%) individuals were unwilling to receive future influenza vaccinations. The main reasons for the unwilling to vaccinate were don’t trust the quality of the vaccine (2428/2655, 91.5%), bad experience with vaccine in the past (2385/2655, 89.8%) and no time for vaccination (2359/2655, 88.9%). While 86.1% believed that Flu was not very harmful, 85.0% thought that annual vaccination was too much trouble. HCWs were also considered the contraindications for vaccination (2201/2655, 82.9%) and Vaccines are not free (2073/2655, 78.1%). In addition, they believed that vaccination is not necessary for good health (1970/2655, 74.2%) and has limited efficacy (1673/2655, 63.0%), and they were also concerned about the side effects of the vaccine (1675/2655, 63.1%), which were reasons for their unwillingness to get vaccinated (Figure 2b).

Suggestions for improving vaccination uptake

The primary suggestion was for the free provision of vaccines, accounting for 92.6% (12029/12985) of the total number. Other important suggestions to encourage vaccination among HCWs included organized mass vaccination incident (11451/12985, 88.2%), increased public health education (10305/12985, 79.4%), and related training and education initiatives (9663/12985, 74.4%). In addition, some suggestions included the provision of incentives for HCWs to vaccinate (7516/12985, 57.9%), and the inclusion of the vaccination uptake in worker assessment (5394/12985, 41.5%) (Figure 3). Figure 3. Suggestions from HCWs willing and unwilling to vaccinate.

Discussion

In this study, we found that HCWs in Shandong Province had a vaccination rate of 67.5% in 2021/2022, which was higher than the nationwide 11.60% figure reported for HCWs during the 2018–2019 flu season,16 but lower than the 78.4% vaccination rate for U.S. HCWs during the 2017–2018 flu season.21 A recent study showed that among 1,697 HCWs surveyed in China, the vaccination rate for the 2021/2022 flu season was 35.4%, which may be related to the economic level of the province.22 Because Shandong Province has a relatively high GDP per capita, the vaccination rate may be higher than the national average. Our research also revealed that 79.6% of HCWs were willing to be vaccinated in 2022/2023, which was higher than the 2021/2022 vaccination rate. However, the U.S. Advisory Committee on Immunization Practices and the Hospital Infection Control Practices Advisory Committee require a flu vaccination rate of 90% for HCWs in the “Healthy People 2020” initiative.23 Although the vaccination rate for HCWs in the study area is relatively high domestically, it is still below the requirements of the WHO and the vaccination levels of HCWs abroad. Given the importance of influenza vaccination for primary HCWs, the vaccination rate needs to be improved.

HCWs aged over 45 years are more likely to be vaccinated against influenza. This difference may be attributed to individuals becoming more aware of health issues as they age, and their accumulated medical knowledge and experience make them more cognizant of the importance of vaccines in disease prevention. Notably, the proportion of highly educated individuals with advanced degrees is greater among HCWs than the general public, and these individuals often have their own understanding of vaccines. This study reveals that higher education levels are correlated with lower vaccination uptakes and willingness, suggesting vaccine hesitancy within this demographic. This finding aligns with the findings of a study by Li Yuan et al. Moreover, the type of healthcare facility and department also influences influenza vaccination rates.24 Vaccination uptake are significantly higher in health centers, and HCWs in public health departments and high-risk departments are more likely to be vaccinated. Compared to other technicians, clinicians and nurses were less likely to be vaccinated. This disparity suggests that HCWs in high-risk departments may be more accepting of vaccination due to their work environment. Despite their extensive knowledge of diseases and treatments, clinical HCWs might have limited understanding of preventive healthcare and are more frequently exposed to adverse vaccination reactions, which can negatively influence their attitudes toward vaccination. Due to their frequent patient contact and increased risk of infection, nurses are more willing to vaccinate. Newly employed young HCWs should enhance their understanding of influenza and its vaccine, especially those with higher education levels and clinical doctors, who should receive more training in vaccination prevention. Furthermore, strengthening the cohesion between the disease control system and multi-departmental, multi-level work is crucial for a comprehensive understanding of vaccine preventive healthcare and is essential for improving vaccination rates.

Our research indicates that hospitals with higher requirements for HCWs to receive influenza vaccinations tend to have higher vaccination rates. In practice, voluntary vaccination policies often fall short of achieving and maintaining a vaccination rate above 40%.25 However, in a U.S. medical center where influenza vaccination was made a condition of employment, the implementation of mandatory vaccination policies resulted in a vaccination coverage rate of over 98% among more than 5,000 HCWs. Additionally, units that implement free vaccination policies and arrange centralized vaccination tend to have higher willingness among HCWs.26 Centralized vaccination is convenient, and numerous studies have shown that measures such as providing free vaccinations and improving accessibility to vaccination services can increase influenza vaccination rates among HCWs.17,27,28 In our survey, we also found that HCWs are more willing to receive vaccinations if free influenza vaccines (92.6%) and organized centralized vaccination (88.2%) are available. Because free vaccination is most likely to promote influenza vaccination among HCWs, local authorities should consider financial subsidies and partial employer contributions. These efforts, combined with local epidemic prevention and control measures, can help formulate influenza vaccination policies for HCWs and provide more convenient vaccination services before each annual flu season. Additionally, the disease control system should also facilitate vaccine procurement across outpatient clinics to ensure the efficient and dynamic distribution of influenza vaccines.

Our research also revealed a significant problem: only 41.5% of HCWs agreed that vaccination rates should be used as a criterion for performance evaluation, and 57.9% believed that incentives should be given to HCWs who vaccinate. The majority of HCWs do not want vaccination uptakes to be used as a criterion for evaluation or incentives, suggesting that the willingness to vaccinate may not be driven by extrinsic motivations (requirements placed on them) but by rather intrinsic motivations (things they feel entitled to do). Therefore, mandatory vaccination could have significant negative effects. As a result, the implementation of mandatory vaccination or incentive-based policies requires further consideration and discussion.

Our study indicates that a greater perception of influenza risk correlated with an increased likelihood of vaccination. Barriers to vaccination include low disease concern, perceived risk of adverse incident, and cognitive or emotional perceptions of the vaccine.29,30 In line with most research findings, the degree of knowledge about influenza and its vaccine is a significant factor in vaccination decisions.29 The more knowledgeable individuals are about influenza and its vaccine, the more they can perceive its risks and benefits; thus, they are more likely to be vaccinated. In July 2018, Changchun Changsheng Biotechnology Co. was found to have violated production standards, leading to the widespread sale of ineffective vaccines in China, which had a significant negative impact on the population. However, our survey shows that this vaccine incident had little effect on the confidence of medical staff in vaccines, differing from the findings of Fanxing Du et al.31 This difference could have arisen because the vaccines in question only had reduced efficacy and did not work as intended, without posing a significant threat to human safety. Studies have shown that medical personnel are less hesitant to vaccinate when they believe in the safety and efficacy of vaccines.32,33 In our study, those who strongly agreed that the flu vaccine is safe were more likely to be vaccinated. Among those unwilling to vaccinate, 91.5% did not trust the quality of vaccines, which is one of the significant barriers to vaccination. This sentiment that is also prominent in the United States and Greece.34,35 The Changchun Changsheng vaccine incident itself may not have directly affected the willingness of HCWs to vaccinate, but we suspect that it may have indirectly triggered their concerns regarding vaccine safety. Therefore, strengthening the strict management of the entire vaccine development process, including research and development, testing, approval, marketing, storage, transportation, and administration. Moreover, increasing clinical research on the quality, safety, and efficacy of vaccines to provide data support and convince medical personnel is essential. Furthermore, 89.9% of healthcare workers reported a lack of time for vaccination, 86.1% perceived influenza as a minor threat, and 85.0% considered annual vaccination to be too cumbersome. Attitudes toward vaccines are associated with influenza vaccine uptake. Future health education for HCWs should aim to alter negative perceptions and attitudes toward the influenza vaccine, foster a scientific understanding of the risks associated with influenza, adopt a rational view of vaccination side effects, bolster confidence in vaccines, and thereby increase vaccination rates.

Nevertheless, the COVID-19 pandemic has persisted, and the low influenza vaccination rates among HCWs have facilitated the transmission of influenza, COVID-19, and various other respiratory diseases. Research has indicated that receiving the influenza vaccine may reduce the severity of COVID-19.36 Our study suggested that 94.8% of HCWs agreed that the COVID-19 pandemic increased their willingness to get a flu vaccine and that they were more likely to be vaccinated, which positively contributed to higher vaccination rates. This finding aligns with the findings of Wang et al.37 who reported that the COVID-19 pandemic has shifted public perception regarding the importance of vaccines for respiratory diseases such as influenza and the willingness of the public to be vaccinated. Paguio et al.38 also observed similar trends in a big data analysis of Google searches, noting a significant global increase in attention to influenza and the influenza vaccine during the pandemic, marked by search peaks. A simultaneous outbreak of influenza and COVID-19 places immense strain on the healthcare system.15 Higher vaccination rates among HCWs could also reduce the workload for COVID-19 screening and effectively decrease the disruption caused by influenza in the control of other respiratory infectious diseases. In summary, effective measures should be taken to increase influenza vaccination coverage among HCWs. The results of the binary logistic regression analysis indicate that workers at hospitals with a history of conducting influenza prevention and control campaigns and training have higher vaccination willingness. Our needs assessment also shows that the majority of HCWs agreed with increasing public education and conducting educational and training programs. A survey study in Australia39 demonstrated that respondents who had participated in immunization education and training in the past 12 months had higher rates of influenza vaccination. The knowledge and attitudes of HCWs toward influenza and the influenza vaccine need further improvement. Therefore, medical and health institutions at all levels need to expand the breadth and intensity of education or publicity for medical personnel in various positions. Enhancing HCW’ understanding of the influenza vaccine and conducting educational campaigns on influenza prevention and vaccine use are essential to promote proactive vaccination and the recommendation of the influenza vaccine.

This study had several limitations. First, the vaccination status of the subjects was self-reported and lacked vaccination records to corroborate, which may introduce recall bias. Second, the study included samples from only certain areas of Shandong Province, which may not be representative. Third, although the survey was developed by experts in influenza and demonstrated reliability post-data collection (Cronbach’s α = 0.87), it was not subjected to a rigorous validation process or reliability assessment prior to its use. In the future, we will continue to track the incidence of influenza-like symptoms among vaccinated and unvaccinated populations, expand the survey population, focus on changes in vaccination patterns, and strengthen the persuasiveness of the conclusions from multiple perspectives to provide references for influenza vaccination and prevention.

Conclusion

In this study, the influenza vaccination uptake among HCWs was 67.5% (8761/12985), with 79.6% (10330/12985) expressing willingness to receive the flu vaccine in the future. A total of 92.7% (12031/12985, p < .001) agreed that the COVID-19 pandemic had increased their inclination to get vaccinated against influenza, whereas94.8% (12308/12985, p < .001) agrees that receiving the flu vaccine remained necessary even after being vaccinated for COVID-19. The COVID-19 pandemic may have had a positive effect on flu vaccination rates. Although Changchun Changsheng vaccine incident may not significantly impact the vaccination uptake among healthcare workers, some HCWs still harbor doubts about vaccine safety, which remains a key reason for vaccine hesitancy. Therefore, it is crucial to strengthen the strict monitoring and management of vaccines throughout the entire process, including research and development, transportation, and administration. Additionally, conducting more related clinical studies to provide data support and convince medical personnel is essential. Free flu vaccine policies, workplace vaccination requirements, and organized mass vaccinations are significant factors in promoting vaccination uptake. Relevant entities should formulate specific flu vaccination policies for HCWs, arrange organized vaccinations, and conduct onsite vaccinations to encourage vaccine uptake among HCWs. Furthermore, intensifying educational efforts for HCPs is vital to enhance, their understanding of influenza and its vaccine on multiple levels and ensure that they correctly recognize the risks of influenza and the value of the vaccine. In addition, comprehensive intervention measures should be taken to effectively increase the flu vaccination uptake.

Renpeng Li is a chief physician and researcher, currently serving as the Director of the Shandong Health Science and Talent Development Center. He is also the Deputy Secretary-General of the Shandong Preventive Medicine Association, the Chair of the Public Health Management Branch, and the Chair of the Public Health Policy Branch. His research focuses on public health management and disease prevention and control.

Zengqiang Kou is a chief physician and researcher of the Institute for Infectious Disease Control and Prevention at the Shandong Center for Disease Control and Prevention. He also serves as a member of the Epidemiology Branch of the Shandong Preventive Medicine Association and a member of the National Immunization Program Technical Working Group at the Chinese Center for Disease Control and Prevention. His research focuses on the field of infectious disease prevention and control.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Yuwei Liu were responsible for analysis and interpretation of data, statistical analysis and writing the article. Ti Liu, Mingxiao Yao and Qiang Wang were responsible for analysis and collection of data. Zengqiang Kou and Renpeng Li were responsible for providing concept and design, study supervision and obtaining funding.

Informed consent statement

Informed consent was obtained from all subjects involved in the study.
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