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Abstract
Objective Vaccination is the most effective strategy for preventing infectious diseases, yet it is underused in young adults. College students are important targets for the influenza vaccine given this population’s low vaccination rates; however, limited research has focused on international college students’ vaccination status. This study examined the relationships between the theory of planned behaviour (TPB; attitudes, perceived behavioural control (PBC) and subjective norms) and students’ intention of receiving an influenza vaccine.
Design, setting and participants A cross-sectional study was conducted with a convenience sample of 222 domestic students recruited via Amazon Mechanical Turk and 197 international students recruited through the Registrar’s Office at a Midwest university.
Results International students had higher levels of PBC, intention and attitudes towards receiving an influenza vaccine compared with domestic students. Being Hispanic (β=−5.33; 95% CI −9.84 to −0.81, p=0.021), up-to-date vaccination status (β=−1.60; 95% CI −2.99 to −0.17, p=0.028) and identifying as smokers (β=−2.94; 95% CI −5.72 to −0.15, p=0.039) significantly lowered college students’ intention. Attitudes (international: β=0.14; 95% CI 0.04 to 0.23, p=0.003; domestic: β=0.14; 95% CI 0.07 to 0.22, p<0.001), subjective norms (international: β=0.40; 95% CI 0.29 to 0.51, p<0.001; domestic: β=0.34; 95% CI 0.23 to 0.44 p<0.001), and PBC (international: β=0.09; 95% CI 0.004 to 0.18, p=0.042; domestic: β=0.10; 95% CI 0.01 to 0.19, p=0.019) were significantly associated with both domestic and international students’ intention of receiving an influenza vaccine.
Conclusion Findings support the TPB’s potential utility to enhance domestic and international college students’ influenza vaccination rates.
- Vaccination
- Health Equity
- Risk management
Data availability statement
Data are available upon reasonable request.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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STRENGTHS AND LIMITATIONS OF THIS STUDY
The study used the Theory of Planned Behaviour to investigate the relationships among attitudes, perceived behavioural control and subjective norms in influencing students’ intentions to receive the influenza vaccine.
The research specifically targeted a vulnerable and at-risk population: international students.
A comparison group was included to enhance the robustness of the findings.
It is important to note that the international student sample was recruited from a single university, which may limit the generalizability of the results.
Introduction
Vaccination is one of the most effective strategies to prevent seasonal influenza and subsequent influenza-related symptoms and deaths according to the WHO.1 The US Centres for Disease Control and Prevention (CDC) recommends that all individuals aged 6 months and older should receive the annual influenza vaccine.2 College students had the lowest influenza vaccination rate. Due to shared classrooms and living spaces, as well as frequent participation in larger social events, the influenza attack rate among college students is high.3 4 Moreover, college students have not been concerned about influenza, have had lower levels of trust in the healthcare system, and have exhibited low intention to get vaccinated.5 6 Seasonal influenza vaccination rates among US college students ranged from 20% to 46%, falling short of the 70% healthy people 2030 target recommendation.7–10 According to the CDC, uptake for the influenza vaccine was 37.1% in 2021–2022 among those aged 18–49, which was 1.3% lower compared with two seasons prior (2019–2020; a pre-pandemic season).11 As a result, the low influenza vaccination rates amid COVID-19 have increased morbidity, mortality and hospitalisations, leading to significant healthcare costs.12 The CDC and the National Foundation for Infectious Diseases have emphasised and encouraged the need for this population to receive influenza vaccination during the COVID-19 pandemic.2 13
According to the Association of International Educators, nearly 1 million international students studied at colleges and universities in the USA during the 2021 to 2022 academic year; however, international students remain an under-researched and vulnerable population, specifically in the health domain.14 15 For example, international students have poor health insurance literacy and low utilisation rates of healthcare services.16 17 They also face numerous challenges, including acculturative stress, financial burdens, academic and/or social difficulties and cultural and linguistic barriers that may delay seeking healthcare services.17–20 Currently, only a few studies have examined immunisation intention and vaccine uptake among international college students. In those studies, researchers found that this population had lower vaccine uptake than domestic students.21–23 Furthermore, vaccine hesitancy is high in international student populations.2 Due to different vaccination schedules and other cultural factors, international students may need to be updated on domestic immunisation policies and informed of vaccine availability to increase vaccination rates.23
The theory of planned behaviour (TPB) is a robust model that is highly predictive of human action in specific contexts.24 25 The model posits that attitudes, subjective norms and perceived behavioural control (PBC) influence behavioural intention and subsequent behaviour. Attitudes refer to an individual’s overall feeling that the behaviour is favourable or unfavourable. Subjective norms are an individual’s estimate of the social pressure to perform a behaviour. PBC is the extent to which an individual believes in their ability to perform the behaviour. The most powerful determinant of an individual’s behaviour, according to the TPB, is the intention to engage in that behaviour, which is influenced by attitudes, subjective norms and PBC.25 Evidence also suggests a strong association between intention for vaccination and receiving a seasonal influenza vaccine.26 Researchers have applied the TPB to analyse individuals’ intentions and attitudes towards vaccination (eg, influenza, COVID-19 and human papillomavirus (HPV) vaccines); however, the findings have been varied.27–30 For example, researchers used the TPB to predict the intentions to receive an influenza vaccine among US college students and indicating only attitudes and subjective norms were significant predictors of the intention.31 Another study applied the TPB to examine how attitudes, subjective norms and PBC influence the influenza vaccination intention among the Chinese population. The findings indicated that subjective norms exert a stronger positive influence on vaccination intention than attitudes. Additionally, PBC acts as a moderator, substituting for attitudes and subjective norms and weakening their positive effects on vaccination behaviour.32
Guided by the TPB, this study aimed to investigate the relationship between theoretical factors (attitudes, subjective norms and PBC) and influenza vaccination intention among international versus domestic college students in the USA. We hypothesised that students’ positive attitudes (ie, “I believe that the influenza vaccine is effective”), subjective norms (ie, “My family thinks I should get the influenza vaccine”) and PBC (ie, “I have the time to get the influenza vaccine”) were associated with greater intention to engage in a given health behaviour (ie, influenza vaccine uptake). The findings could guide evidence-based health promotion strategies aimed at increasing annual seasonal influenza vaccination rates among college students. Given the low uptake of the vaccine in this population, it is crucial for them to be vaccinated to prevent and help minimise the spread of infection on campuses and within surrounding communities.
Methods
Design and participant recruitment
This study was reviewed and classified as exempt by the Michigan State University’s Institutional Review Board (MSU study ID: STUDY00006088). A non-experimental, cross-sectional study design was used for this research. Domestic and international students aged 18–26 and enrolled at institutions of higher education in the USA were invited for participation. Using a convenience sampling approach, we recruited domestic students from Amazon’s Mechanical Turk programme and international students from a large Midwest university via an invitation email sent by the university’s Office of the Registrar. The Amazon’s Mechanical Turk programme was used due to its promise for conducting research in the social sciences and medical fields.33 An anonymous survey link was distributed to eligible participants who were informed about the study purpose, the voluntary nature of their participation and the measures taken to ensure data confidentiality. Data collection period was from September through October 2021. Participants received $10 compensation on completion of the questionnaire. Using the G*Power program,34 with a type I error=0.05, 13 total predictors, three tested predictors (attitudes, subjective norms and PBC), we assume a small effect size f2=0.11 based on prior literature,30 a sample size of 159 in each group was needed to achieve a 95% study power when using hierarchical multiple linear regression models to examine factors related to the intention of receiving an influenza vaccine.
Measurements
The measurements used in this study were adapted from Catalano et al.29 The original instrument used to assess attitudes, subjective norms, PBC and behavioural intention for HPV vaccination among college men demonstrated good internal reliability, construct validity and predictive validity.29 In our previous study regarding COVID-19 vaccines and boosters among college students, we adapted the instrument and the results from the factor analysis support the strong construct validity and validity.30 With permission from the original developers,29 we adapted the instrument by replacing ‘HPV vaccine’ with ‘influenza vaccine to measure attitudes, subjective norms, PBC and behavioural intention in our target sample.
An attitude towards receiving an influenza vaccine was defined as ‘an individual’s overall feeling that getting vaccinated with an influenza vaccine is favourable or unfavourable’. Attitudes towards receiving an influenza vaccine in the next 12 months were measured using seven 7-point semantic differential scale items. A possible construct score ranged from 7 to 49. A sample question was as follows: “I think getting the influenza vaccine in the next 12 months would be: Not at all protective (score 1)—Extremely protective (score 7).” A higher sum score indicates that the participant has a greater positive attitude towards receiving an influenza vaccine. In this study, the Cronbach’s alpha for this subscale was 0.96 among international students and 0.88 among domestic students.
Subjective norms were operationalized as “an individual’s general belief that significant people in their lives, such as family members and/or close friends, thought they should or should not get the influenza vaccine in the next 12 months.” The subjective norms’ subscale included four 7-point semantic differential items with a possible score ranging from 4 to 28. A sample question was: “My parents would like me to get the influenza vaccine in the next 12 months: Completely disagree (score 1)—Completely agree (score 7).” A higher sum score indicates that the participant has greater subjective norms of getting an influenza vaccine. The Cronbach’s alpha for the subjective norms subscale was 0.96 for international students and 0.89 for domestic students.
PBC was defined as ‘the extent to which a person believes they are in control of getting an influenza vaccine in the next 12 months’. This subscale consisted of six 7-point semantic differential rating items and a possible score ranging from 6 to 42. A sample question included: ‘For me to get an influenza vaccine in the next 12 months would be: Extremely difficult (score 1)—Extremely easy (score 7)’. A higher sum score suggests that the participant has a greater PBC of getting an influenza vaccine. The Cronbach’s alpha for the PBC subscale was 0.94 for international students and 0.86 for domestic students.
Behavioural intention was defined as ‘college students’ readiness to get an influenza vaccine in the next 12 months’. This subscale was assessed with three 7-point semantic differential rating items, with a possible score ranging from 3 to 21. A sample question was: ‘I plan to get an influenza vaccine in the next 12 months: Completely disagree (score 1)—Completely agree (score 7)’. A higher score indicates that the participant has a strong willingness to get an influenza vaccine. For the behavioural intention subscale, Cronbach’s alpha was 0.98 for international students and 0.88 for domestic students.
Respondents’ sociodemographic information, including age, sex, race/ethnicity and education, was collected. Studies have found that people with chronic illnesses and tobacco users were more vaccine hesitant.35 36 Thus, self-reported health and lifestyle questions, such as health status, smoking history and up-to-date vaccination status, were also collected. For health status, participants were asked to answer if (1) they were currently diagnosed with any diseases (eg, diabetes, hypertension, an autoimmune disease, hepatitis asthma or cardiac disease); (2) had a chronic medical condition requiring medication or regular physician visits; or (3) had overall very good health with no disease. For smoking status, participants were asked to identify if they (1) smoked, (2) never smoked or (3) used to smoke, but quit. For vaccination status, participants were asked to indicate how up-to-date they were on overall vaccinations with responses including (1) currently up to date, (2) no, but planning to be updated, or (3) no, and not planning to be updated.
Patient and public involvement
None.
Data analysis
All analyses were performed in SPSS for Windows V.28.0 (SPSS, Chicago, IL). Descriptive statistics were used to describe the data based on counts and frequencies for categorical data and means and SD for continuous data. The independent t-tests, based on the characteristics of the examined variables, were performed to determine differences in study variables between domestic and international students. Cronbach’s alpha was used to estimate the reliability of the internal consistency. Hierarchical multiple linear regression analysis was used to assess the relationships of attitudes, subjective norms, PBC and intention of receiving influenza vaccines. In Block 1, sociodemographic and health-related variables were entered, including age, sex, race/ethnicity, smoking behaviour, chronic illnesses, health insurance and vaccination history. In Block 2, attitudes towards receiving an influenza vaccine, subjective norms and PBC were entered. Results were considered statically significant when p<0.05. Missing data were controlled by using group averages if participants missed answering one or two questions. If participants missed answering more than three questions, that participant was excluded from the analysis.
Results
Characteristics of participants
As listed in table 1, the sample consisted of 222 domestic and 197 international college students. For the international students, the mean age was 20.27 years old (±2.75). Of these participants, 86 were female (44%), 137 were Asian (70%) and 73 were college freshman (37%). The majority (167 participants) indicated that they had never smoked (85%), and 147 self-reported they were currently up to date on their overall vaccinations (75%). For the domestic students, the mean age was 24.62 years old (±3.38). Of these participants, 110 were female (50%), 59 (27%) indicated that they had never smoked, 172 were currently up to date on the overall vaccination (78%) and 171 were White (77%).
Sociodemographic and health-related variables
The surveyed international students were 4 years younger (p<0.001), reported better health status, had a lower prevalence of smoking (p=0.010) and the majority had health insurance (p<0.001) compared with domestic students. More domestic students reported being diagnosed with chronic illnesses than international students (p<0.001). Additionally, a greater proportion of the domestic students indicated they were married, while the majority of international students were single (p<0.001).
TPB-based psychological factors between international and domestic students
As shown in table 2, international students had significantly more positive attitudes towards receiving the influenza vaccine (41.67±8.55 vs 38.96±7.44; p<0.001) and significantly higher perceived behavioural control (34.02±7.80 vs 32.89±5.73; p=0.044) compared with domestic students. Although domestic students reported higher subjective norms (21.53±4.88 vs 21.40±6.18; p=0.409), there was no statistical significance when compared with international students. While international students expressed a higher vaccination intention (15.92±5.18) than the domestic students (15.89±3.98), no significant difference was found between the two groups (p=0.476).
Comparisons between domestic and international students
Determinants of intention to receive an influenza vaccine
Results of the hierarchical multiple linear regression using the entire sample were presented in table 3. In the first step of the analysis (Block 1), sociodemographic and health-related variables explained 10% of the variance in the intention of receiving an influenza vaccine. Current smokers (β=−1.62; 95% CI −2.86 to −0.39, p=0.010) and having up-to-date vaccines (β=−1.47; 95% CI −2.60 to −0.36, p=0.010) decreased students’ intention to receive an influenza vaccine. In the second step of the analysis (Block 2), Block 1 and TPB-based psychological factors explained 60% of the variance in intention of receiving an influenza vaccine. Attitudes towards receiving an influenza vaccine (β=0.13; 95% CI 0.07 to 0.18, p<0.001), subjective norms (β=0.39; 95% CI 0.32 to 0.46, p<0.001) and perceived behavioural control (β=0.09; 95% CI 0.03 to 0.15, p=0.002) were significantly related to the intention of receiving an influenza vaccine.
Factors associated with intention of receiving influenza vaccine
When comparing international and domestic students in the first step of the analysis (Block 1), being a smoker (β=−2.94; 95% CI −5.72 to −0.15, p=0.039) and Hispanic (β=−5.33; 95% CI −9.84 to −0.81, p=0.021) were statistically correlated with a lower intention of receiving an influenza vaccine among international students, while having up-to-date vaccines (β=−1.60; 95% CI −2.99 to −0.17, p=0.028) was significantly correlated with a lower intention of receiving an influenza vaccine among domestic students. In the second step of the analysis (Block 2), all variables explained 60% and 62% of the variance in intention of receiving an influenza vaccine for international and domestic students, respectively. Attitudes (international: β=0.14; 95% CI 0.04 to 0.23, p=0.003; domestic: β=0.14; 95% CI 0.07 to 0.22, p<0.001), subjective norms (international: β=0.40; 95% CI 0.29 to 0.51, p<0.001; domestic: β=0.34; 95% CI 0.23 to 0.44, p<0.001), and PBC (international: β=0.09; 95% CI 0.004 to 0.18, p=0.042; domestic: β=0.10; 95% CI 0.01 to 0.19, p=0.019) were significantly related to a higher intention of receiving an influenza vaccine (see table 3).
Discussion
The purpose of this study was to investigate the relationship between TPB constructs (ie, attitudes, subjective norms, PBC) and influenza vaccination intention among domestic versus international students. To compare domestic college students’ intention to receive influenza vaccine, one prior study investigated 277 domestic college students and reported mildly positive attitudes towards the influenza vaccine (mean±SD = 18±5.40), neutral subjective norms (mean±SD = 11.7±4), positive PBC (mean±SD = 21.1±3.5) and neutral behavioural intentions (mean±SD = 11±5.4).31 As a result, our surveyed domestic college students had higher intention of receiving an influenza vaccine. Another article surveyed 158 undergraduate public health students aged 18–54, with a mean age of 22.49 (SD=3.674), regarding their attitudes and barriers related to seasonal influenza vaccination uptake. The study found that the majority of respondents (88.4%) reported being encouraged to receive the seasonal influenza vaccine. However, the overall reported vaccination rate among respondents was only 43.0%.37
The surveyed international students had higher scores on the intention of receiving influenza vaccination, attitudes towards receiving influenza vaccination, and PBC compared with the domestic students; however, domestic students had higher subjective norms. The lower subjective norms among international students may be attributed to the fact that the influenza vaccine is not widely common in their home countries and is not included in mandatory immunisation programmes in places like China and India.38 39 For example, the overall influenza vaccination rate among 74 484 Chinese adults and older adults was only 2.4% during the 2014 to 2015 season.38 Furthermore, the contributions of each of the TPB constructs in influenza vaccine intention for international and domestic college students were different than prior research. For example, one prior study reported that only attitudes and subjective norms were significantly associated with college students’ intention to vaccinate against influenza.31 One possible reason could be related to the timing of data collection. Our data were collected during the COVID-19 pandemic and college students were strongly encouraged to receive the influenza vaccine by their healthcare providers and family members. Trust is a primary factor influencing vaccination uptake, and physicians’ advocacy is recognised as one of the most significant influences, as it may enhance trust among college students. This encouragement could positively impact their perceived behavioural control.4
Half of the domestic students in our study indicated they had some type of chronic illness. Consistent with our study, other studies also found that domestic students had more chronic illnesses as well as lower scores on attitudes, PBC and intention towards getting an influenza vaccine compared with international students. One possible reason is the misunderstanding or fear of adverse reactions to vaccination.40 Education and interventions that provide accurate and clear recommendations on the safety of vaccines could help college students with chronic health conditions make an informed decision regarding vaccination.41 42
Among the domestic students surveyed, those with up-to-date vaccinations reported a lower intention to receive the influenza vaccine, consistent with previous research.43 44 One study found that college students with current vaccinations felt they were in good health and therefore saw no need for the influenza vaccine.43 Another study confirmed that individuals who believe they are healthy are less likely to consider vaccination necessary.44 However, this trend did not extend to the international students surveyed. In our study, up-to-date vaccination status did not seem to affect the intention to receive the influenza vaccine among international students.
When merging the international and domestic students into one group, being a current smoker was significantly associated with a lower intention of receiving an influenza vaccine. Our finding is consistent with those from the Korea National Health and Nutrition Examination Survey showing that current smokers and heavy smokers had lower influenza vaccination rates compared with non-smokers.44 A recent study investigating factors impacting influenza vaccination uptake among college students in Lebanon found that college students who were current or former smokers had significant unvaccinated rates compared with students who had never smoked; these individuals reported not needing the vaccine.45 Given that smokers have a higher risk of hospitalisation due to influenza infection, healthcare providers should encourage smokers to receive an influenza vaccine annually and to quit smoking for improved health outcomes.46
Consistent with the racial and ethnic disparities and health inequity regarding severity and influenza vaccination coverage, our study found that being Hispanic was significantly related to a lower intention to receive influenza vaccination among international students.47 48 According to the CDC, Hispanic adults had the lowest influenza vaccination rate compared with White, Black and Asian adults during the 2021 to 2022 influenza season.49 The possible reasons for their lower influenza vaccination rate are distrust of the healthcare system, lack of health insurance, negative perceptions about vaccine safety, language barriers and higher levels of concerns about side effects.45–47 Vaccine hesitancy and decision-making regarding vaccination are closely tied to trust in government and public health professionals.50 Individuals must trust the information they receive when making choices about vaccines.51 52 As trust in government and public health officials is essential,46 initiatives could include providing clear, accurate and transparent information and timely updates, and leveraging trusted figures (eg, healthcare providers) in the communication. Healthcare providers’ advocacy for vaccination is recognised as one of the most significant factors shaping public attitudes towards vaccination.51 53 54 Engaging healthcare providers to communicate directly with their patients may be beneficial, as these providers can leverage the trust their patients have in them to address vaccine concerns and increase vaccination rates.53 It is also essential to involve messengers beyond individual healthcare providers, including federal and state/local public health officials, to communicate the benefits of vaccination. Other reasons for low influenza vaccination are negative perceptions, lack of motivation, inconvenience or fear of needles.41 55 To counteract negative perceptions and promote positive vaccination attitudes among college students, it is important to highlight information about influenza’s prevalence, routes of transmission and high-risk groups, as well as the positive benefits of receiving the influenza vaccination, such as increased safety, effectiveness against influenza and the vaccine’s protections.30 Healthcare providers can promote positive attitudes towards influenza vaccine uptake by providing reliable and credible information about vaccine safety and emphasising the benefits of the vaccine and its efficacy to facilitate college students’ confidence in the vaccine.7 50–54 56 Additionally, using social media appropriately can enhance vaccination intention by demonstrating the contribution of subjective norms (eg, family and close friends sharing that they have received vaccines or ideas that the vaccination is good, helpful and useful).56–58 It is also essential for college and university health centres to provide information on vaccine safety in various languages and affordable and/or free vaccine events at campus health centres and mobile clinics in student neighbourhoods.39 48 49 56
This study has some limitations. The surveyed international students were recruited from one institution, limiting the generalizability of the findings. Additionally, some important factors associated with vaccination intention, such as perceived risk and knowledge of influenza and influenza vaccine were not collected. Furthermore, the cross-sectional nature of the study limits the ability to draw causal inferences between TPB constructs and behaviour. A more rigorous longitudinal study design is recommended to further assess the effects of TPB constructs on vaccination behaviour and to evaluate the relative contributions of each individual construct.
Summary
This study found that TPB-based psychological factors, including attitudes, subjective norms and PBC were related to the intention of receiving an influenza vaccine among domestic and international college students. We also discovered other important factors such as current smoking status, being Hispanic and up-to-date vaccination status that were associated with lower vaccination intention in our sample. Future vaccination programmes should consider these influential factors. It is important to target college students and provide updated information and statistics regarding the benefits of the influenza vaccination to encourage a sense of individual control over health decisions. When working with international students, local health departments and college healthcare centres should make efforts to actively offer tailored vaccination opportunities to international students, as immunisation practices vary by country.
Supplemental material
Data availability statement
Data are available upon reasonable request.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants but Michigan State University study ID: STUDY00006088. Principal investigator: Cheng-Ching LiuCategory: Exempt 2(ii) exempted this study. Participants gave informed consent to participate in the study before taking part.
Acknowledgments
Special thanks to Dr Catalano and her research team for granting us permission to use the instrument in our study. We would also like to express our gratitude to the research participants for their valuable time and effort in completing the study.
References
Footnotes
Contributors All authors contributed to the planning, conduct and reporting of the study. CHL undertook the analysis and drafting of the article. AC-CC, JL, CL, RA and NZ provided technical expertise to enable the analysis of the data. AC-CC, JL and CL provided feedback on various drafts of the article. CHL is the guarantor of the study. CHL attests that all listed authors meet the authorship criteria and that no other authors meeting the criteria have been omitted.
Funding The authors would like to thank the Sherwood foundation (RN031103—LIUSF) who provided research funding to help us focus on the vaccination status among international and domestic students in the USA. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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