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Pandemic influenza H1N1 vaccination intention: psychosocial determinants and implications from a national survey, Taiwan

Jiun-Hau Huang, Yen-Yu Miao, Pei-Chun Kuo
DOI: http://dx.doi.org/10.1093/eurpub/ckr167 796-801 First published online: 18 November 2011

Abstract

Background: Vaccination has been recommended as an effective way to protect people from severe illness during influenza pandemics; however, little is known about the acceptability and psychosocial determinants of intention to receive vaccination against pandemic influenza A/H1N1 (pH1N1). Methods: A national computer-assisted telephone interview survey using random digit dialing was conducted during 28–30 October 2009 among residents of Taiwan aged ≥15 years. Results: Of the 1079 participants interviewed, 70.1% reported intention to receive pH1N1 vaccination. Multivariate logistic regression analysis showed that participants who perceived pH1N1 in Taiwan to be much more severe than that in other countries [adjusted odds ratio (AOR) = 1.94; 95% confidence interval (CI) = 1.05–3.60], who agreed (AOR = 2.44; 95% CI = 1.30–4.58) or strongly agreed (AOR = 2.53; 95% CI = 1.38–4.65) that contracting pH1N1 would have a great impact on their daily life, who perceived pH1N1 vaccination to be very effective in preventing pH1N1 (AOR = 2.64; 95% CI = 1.61–4.33) and who considered receiving vaccination not very difficult (AOR = 8.97; 95% CI = 6.05–13.29) or not at all difficult (AOR = 30.72; 95% CI = 19.24–49.04) were more inclined towards getting vaccinated against pH1N1. Conclusion: These specific and modifiable health beliefs have practical implications for prevention and policy making, and highlight the importance of minimizing perceived barriers while convincing the public of the seriousness of the disease and effectiveness of vaccination when promoting vaccination programmes.

Introduction

A new strand of influenza A/H1N1 virus was first reported to cause severe illness in April 2009.1 Based on its global surveillance data, the World Health Organization (WHO) raised the level of influenza pandemic alert to Phase 5 on 29 April 20092 and subsequently to Phase 6, the highest level of alert, on 11 June 2009.3 According to WHO's weekly update, pandemic influenza A/H1N1 (pH1N1) has caused over 18 449 deaths and has spread to more than 214 countries and overseas territories or communities.4

In Taiwan, the first laboratory-confirmed severe case of pH1N1 was identified on 17 July 2009.5 Since then, 998 severe cases have been reported, including 51 deaths.6 Per Taiwan's Department of Health statistics, 12 clusters of influenza infections were reported in the month of May alone in 2010, two of which were verified clusters of pH1N1 infections in the army, including 16 soldiers confirmed by Taiwan Centers for Disease Control (Taiwan CDC) to be pH1N1 cases.7 The student population was affected as well—e.g. a 15-year-old junior high school student died of pH1N1 on 5 May 2010, just 9 days after the first appearance of flu-like symptoms;8 in the following month, a 21-year-old college student with no chronic condition or other disease also succumbed to pH1N1.9 Further cases of death occurred in communities, too—e.g. a 56-year-old man died of pH1N1 on 8 August 2010, whose son also died from severe pneumonia caused by pH1N1.10 The above findings suggest that pH1N1 virus may still be circulating in Taiwan.

During the 2009 pandemic, pH1N1 vaccines were first made available in Taiwan in November 2009 and offered without charge to the public according to a vulnerability-based vaccination priority list predetermined by Taiwan CDC.11 As a public health measure that can protect a large population against the influenza pandemic and its resulting impact on society, vaccination has long been regarded as one of the most effective ways to prevent severe illness during influenza pandemics.12,13 Accordingly, an extensive body of literature has been devoted to examining vaccination effectiveness.14–16 Although critical, this research alone will not necessarily result in better pandemic control, as the general public may not intend to be vaccinated even if the vaccines are effective. Therefore, it is important to understand the factors, including people's attitudes and perceptions, which influence their intention to get vaccinated.

To our knowledge, few studies have focused on pH1N1 vaccination intention and its associated factors.17 Among those which explored the possible determinants of intention to receive pH1N1 vaccination, some only included demographic variables in their multivariate models to explain people's vaccination intention,18 while others lacked theoretical foundations for their measures.19,20 A recent investigation incorporated health behaviour theories in studying pH1N1 vaccination intention in a sample of 301 residents in Hong Kong,21 although it only partially applied certain theoretical constructs. Therefore, this field of research could benefit from additional studies to systematically examine theory-driven psychosocial variables that influence people's pH1N1 vaccination intention.

The purpose of this study was to identify psychosocial determinants of people's pH1N1 vaccination intention in the Taiwanese general population, using a large national sample. We employed the Health Belief Model (HBM)22 as the overarching theoretical framework to guide both the development of the measures and analyses. Conducted in the midst of the 2009 pandemic before any pH1N1 vaccine was available in Taiwan, this study captured a snapshot of how people perceived and responded to pH1N1, a novel infectious disease then, and collected information on theory-driven psychosocial variables that purportedly would affect people's vaccination intention. Hence, these findings could help illuminate what psychosocial covariates might determine people's vaccination intention in the face of uncertainty, thereby informing future pandemic control initiatives when new emerging infectious diseases like pH1N1 arise. To our knowledge, there are no published data on Taiwan's national prevalence estimate of pH1N1 vaccination intention. Thus, this study may also serve to provide insights into the acceptability of the pH1N1 vaccine in Taiwan, an integral part of the global health community yet currently not a member state of the WHO.

Methods

Sampling and data collection

Data were collected through a computer-assisted telephone interview (CATI) survey conducted between 28 and 30 October 2009 during the Phase-6 pandemic and before any pH1N1 vaccine was available in Taiwan. Proportional stratified random digit dialing (RDD) by region was used to select a geographically representative national sample of the general population, which consisted of residents of Taiwan aged ≥15 years. Over 96% of the households in Taiwan have a landline telephone installed.23 All interviews were conducted 6–10 PM during the weekdays to avoid over-representation of the non-working population. Prior to each interview, verbal informed consent was obtained from the participant or from the guardian if the participant was <18 years of age, and each interview lasted for about 15–20 mins. The study protocol was reviewed and approved by the Institutional Review Board of the National Taiwan University College of Public Health. In total, 1583 participants were identified and 1085 completed the interview; the response rate was 68.5%. Notably, the sample size needed to produce a national estimate for the population proportion who intended to receive pH1N1 vaccination, with a 95% confidence interval and a precision level of 0.03 (i.e. margin of error), was 1068 [ = 0.5 × (1–0.5) × (1.96/0.03)2]. The resulting sample distribution was comparable with the national population distribution as per Taiwan's 2009 census data24—e.g. by region, 45.0% of the sample was from the north (vs. 44.8%), 22.4% centre (vs. 22.4%), 27.3% south (vs. 27.9%) and 5.2% east (vs. 5.0%); by gender, 52.7% of the sample was female (vs. 50.0%); the age distribution also approximated that reported in the census.

Measures

The development of the survey questionnaire was informed by literature reviews, expert consultations and in-depth interviews with members of the general population. In a pilot test, the questionnaire was administered by telephone to 30 members of the general public to ensure clarity and appropriateness of the survey questions.

Vaccination intention

Participants were asked: ‘Do you intend to receive vaccination against pH1N1? (yes/no)’

Knowledge and theory-based health beliefs

To assess their knowledge about pH1N1, participants were asked multiple-choice questions. For example: ‘What type of influenza virus is pH1N1? (type A/B/C)’ and ‘Through what routes is pH1N1 transmitted? (contact/airborne/air droplet)’. This study also examined HBM-based health beliefs that could help explain pH1N1 vaccination intention. Questions derived from the HBM included perceived susceptibility [e.g. ‘How likely are you to contract pH1N1 in the future?’ (rated from 1 ‘very unlikely’ to 4 ‘very likely’)] and perceived severity [e.g. ‘Do you agree that contracting pH1N1 would have a great impact on your daily life?’ (rated from 1 ‘strongly disagree’ to 4 ‘strongly agree’)]. Also included were perceived benefits [e.g. ‘How effective do you think vaccination is in preventing pH1N1?’ (rated from 1 ‘not at all effective’ to 4 ‘very effective’)] and perceived barriers [e.g. ‘How difficult is it for you to receive pH1N1 vaccination as suggested during the pandemic?’ (rated from 1 ‘not at all difficult’ to 4 ‘very difficult’)]. Finally, cues to action were assessed [e.g. ‘Did you have influenza-like symptoms during the past month?’ (yes/no)].

Sociodemographic characteristics

Sociodemographic characteristics were also examined in association with pH1N1 vaccination intention, including gender, age, education, marital status, employment status, household income and region of residence.

Statistical analysis

First, participants who had already contracted pH1N1 before the interview (n = 6) were excluded from the analysis, resulting in a final sample of 1079 participants. Pearson's chi-square test was then used to examine the associations between the independent variables (i.e. knowledge, HBM-based health beliefs and sociodemographic characteristics) and the outcome variable (i.e. pH1N1 vaccination intention). Next, multivariate stepwise logistic regression analysis was conducted to inform the selection of independent variables to be included in the final model; those remaining statistically significant (P < 0.05) in the multivariate procedure were retained in the final model as covariates of the outcome variable. Hosmer–Lemeshow test was also performed to examine the goodness of fit of the final model. All statistical analyses were carried out with SPSS 17.0.

Results

Sociodemographic characteristics and vaccination intention

The sociodemographic characteristics of the participants (n = 1079) are as follows (Table 1): 52.7% were female; nearly 80% were aged 25–64 years; 30.6% had a college or higher degree; 63.9% were married or cohabited; 57.4% were employed and 10.5% were students; 42.2% had a monthly household income < NT$50,000 (around US$1,700; €1,200); 45.0% lived in northern Taiwan. Approximately 7 in 10 participants (70.1%) reported that they intended to receive pH1N1 vaccination.

View this table:
Table 1

Sociodemographic characteristics and their univariate associations with intention to receive pH1N1 vaccination during the 2009 pandemic in Taiwan (n = 1079)

VariableTotalIntend to receive vaccination
No. (Col %)No. (Row %)χ2 (df)P-value
Gender11.681 (1)0.001
    Male510 (47.3)383 (75.1)
    Female569 (52.7)373 (65.6)
Age (years)10.06 (4)0.039
    15–1757 (5.3)44 (77.2)
    18–2493 (8.6)70 (75.3)
    25–44430 (39.9)281 (65.3)
    45–64428 (39.7)305 (71.3)
    ≥6571 (6.6)56 (78.9)
Education5.298 (2)0.071
    Senior high or below592 (54.9)432 (73.0)
    Junior college157 (14.6)107 (66.2)
    College or above330 (30.6)220 (66.7)
Marital status0.715 (2)0.699
    Single338 (31.3)235 (69.5)
    Married/cohabited689 (63.9)487 (70.7)
    Divorced/separated/ widowed52 (4.8)34 (65.4)
Employment status11.222 (4)0.024
    Student113 (10.5)85 (75.2)
    Employed619 (57.4)418 (67.5)
    Retired93 (8.6)75 (80.6)
    Homemaker189 (17.5)127 (67.2)
    Unemployed65 (6.0)51 (78.5)
Household income (NT$/month)3.715 (3)0.294
    <50 000a455 (42.2)319 (70.1)
    50 000–99 999322 (29.8)228 (70.8)
    ≥100 000135 (12.5)86 (63.7)
    Not willing to tell167 (15.5)123 (73.7)
Region of residence0.768 (3)0.857
    North486 (45.0)338 (69.5)
    Centre242 (22.4)175 (72.3)
    South295 (27.3)204 (69.2)
    East56 (5.2)39 (69.6)
Total1079 (100)756 (70.1)
  • a: NT$50 000 is approximately US$1700; €1200.

The univariate associations between sociodemographic characteristics and pH1N1 vaccination intention are also reported in Table 1. Of note, males were significantly more likely than females to intend to get vaccinated. Age was also significantly associated with vaccination intention, with the elderly (≥65 years) and younger (15–17 years) participants more likely, and those aged 25–44 years least likely, to intend to receive vaccination. In addition, significantly higher proportions of retirees, students and unemployed participants reported vaccination intention, compared with employed participants and homemakers. The chi-square comparisons were not statistically significant with regard to education, marital status, household income and region of residence.

Knowledge, theory-based health beliefs and vaccination intention

Table 2 presents participants’ knowledge about pH1N1 and HBM-based health beliefs in association with their vaccination intention. Neither knowledge nor perceived susceptibility was significantly associated with vaccination intention. Regarding perceived severity, 38.4% of the participants perceived pH1N1 to be less fatal than avian influenza, and 52% perceived the pandemic in Taiwan to be slightly or much more severe than that in other countries; neither chi-square comparison was statistically significant. On the other hand, 30.9 and 60.1% of the participants agreed and strongly agreed, respectively, that contracting pH1N1 would have a great impact on their daily life, and were significantly more likely to intend to be vaccinated than their counterparts.

View this table:
Table 2

Knowledge, HBM-based health beliefs and their univariate associations with intention to receive pH1N1 vaccination during the 2009 pandemic in Taiwan (n = 1079)

VariableTotalIntend to receive vaccination
No. (Col %)No. (Row %)χ2 (df)P-value
Knowledge
    Knowledge about the type of pH1N1 virus1.32 (1)0.251
        Incorrect633 (58.7)435 (68.7)
        Correct446 (41.3)321 (72.0)
    Knowledge about the routes of pH1N1 transmission0.811 (1)0.368
        Incorrect808 (74.9)572 (70.8)
        Correct271 (25.1)184 (67.9)
Perceived susceptibility
    Perceived pH1N1 to be more transmissible than AI1.818 (1)0.178
        No372 (34.5)251 (67.5)
        Yes707 (65.5)505 (71.4)
    Perceived likelihood of contracting pH1N10.456 (2)0.796
        Unlikely/very unlikely642 (59.5)445 (69.3)
        Likely380 (35.2)271 (71.3)
        Very likely57 (5.3)40 (70.2)
Perceived severity
    Perceived pH1N1 to be less fatal than AI0.688 (1)0.407
        No665 (61.6)472 (71.0)
        Yes414 (38.4)284 (68.6)
    Perceived severity of the pandemic in Taiwan compared with other countries3.61 (2)0.165
        Not severe/not at all severe518 (48.0)352 (68.0)
        Slightly more severe453 (42.0)321 (70.9)
        Much more severe108 (10.0)83 (76.9)
    Contracting pH1N1 would have a great impact on daily life12.13 (2)0.002
        Disagree/strongly disagree97 (9.0)53 (54.6)
        Agree333 (30.9)237 (71.2)
        Strongly agree649 (60.1)466 (71.8)
Perceived benefits
    Perceived effectiveness of vaccination in preventing pH1N194.63 (2)<0.0001
        Not very effective/not at all effective197 (18.3)98 (49.7)
        Effective458 (42.4)295 (64.4)
        Very effective424 (39.3)363 (85.6)
Perceived barriers
    Perceived difficulty of receiving vaccination as suggested during the pandemic386.14 (2)<0.0001
        Difficult/very difficult332 (30.8)99 (29.8)
        Not very difficult296 (27.4)236 (79.7)
        Not at all difficult451 (41.8)421 (93.3)
Cues to action
    Had influenza-like symptoms during the past month0.121 (1)0.728
        No987 (91.5)693 (70.2)
        Yes92 (8.5)63 (68.5)
    Knew people who had influenza-like symptoms during the past month1.263 (1)0.261
        No790 (73.2)561 (71.0)
        Yes289 (26.8)195 (67.5)
    Knew people who had contracted pH1N1a0.392 (1)0.531
        No865 (81.5)608 (70.3)
        Yes197 (18.5)134 (68.0)
  • AI: avian influenza.

  • a: This item has 17 missing values.

Concerning perceived benefits, 42.4 and 39.3% of the participants considered pH1N1 vaccination effective and very effective in preventing pH1N1, respectively, and they were significantly more likely to report vaccination intention than their counterparts. Regarding perceived barriers, 27.4 and 41.8% of the participants thought it was not very difficult and not at all difficult, respectively, to receive pH1N1 vaccination as suggested during the pandemic, and they were significantly more likely to intend to get vaccinated than their counterparts. Finally, variables concerning cues to action were not significantly associated with vaccination intention.

Multivariate analysis for covariates of vaccination intention

Table 3 presents the final multivariate logistic regression model estimating the effects of these psychosocial covariates on participants’ pH1N1 vaccination intention. The Hosmer–Lemeshow goodness-of-fit test yielded a large P-value of 0.82, suggesting a model with good predictive value. Also, the final model had a correct classification rate of 0.89 for those with vaccination intention, indicating that the model could correctly classify 89% of the participants who intended to get vaccinated. After all other variables in the model were controlled for, males were found 42% more likely than females to intend to receive vaccination [adjusted odds ratio (AOR) = 1.42]. Compared with those aged 25–44 years, those aged 18–24 (AOR = 2.02) and ≥65years (AOR = 2.19) were more than twice as likely to intend to get vaccinated. Compared with participants who had a monthly household income ≥ NT$100 000 (US$3,400; €2400), those with a monthly household income between NT$50 000 and 99 999 were 81% more likely to intend to receive vaccination (AOR = 1.81).

View this table:
Table 3

Multivariate logistic regression model for covariates of intention to receive pH1N1 vaccination during the 2009 pandemic in Taiwan (n = 1079)

VariableAOR (95% CI)
Sociodemographic characteristics
    Gender
        Male1.42 (1.01–2.01)*
        Female (ref)1.00
    Age (years)
        15–172.08 (0.89–4.87)
        18–242.02 (1.07–3.80)*
        25–44 (ref)1.00
        45–641.26 (0.86–1.85)
        ≥652.19 (1.02–4.72)*
    Household income (NT$/month)
        <50 000a1.39 (0.81–2.37)
        50 000–99 9991.81 (1.03–3.18)*
        ≥100 000 (ref)1.00
        Not willing to tell1.72 (0.90–3.30)
Perceived severity
    Perceived severity of the pandemic in Taiwan compared with other countries
        Not severe/not at all severe (ref)1.00
        Slightly more severe1.05 (0.73–1.52)
        Much more severe1.94 (1.05–3.60)*
    Contracting pH1N1 would have a great impact on daily life
        Disagree/strongly disagree (ref)1.00
        Agree2.44 (1.30–4.58)**
        Strongly agree2.53 (1.38–4.65)***
Perceived benefits
    Perceived effectiveness of vaccination in preventing pH1N1
        Not very effective/not at all effective (ref)1.00
        Effective1.16 (0.75–1.81)
        Very effective2.64 (1.61–4.33)***
Perceived barriers
    Perceived difficulty of receiving vaccination as suggested during the pandemic
        Difficult/very difficult (ref)1.00
        Not very difficult8.97 (6.05–13.29)****
        Not at all difficult30.72 (19.24–49.04)****
  • Ref: reference group; CI: confidence interval. *P < 0.05; **P < 0.01; ***P < 0.005; ****P < 0.0001.

  • a: NT$50 000 is approximately US$1700; €1200.

Participants who perceived the pandemic in Taiwan to be much more severe compared with other countries were almost twice as likely to intend to receive vaccination (AOR = 1.94) as those who did not consider it severe. Those who agreed (AOR = 2.44) and strongly agreed (AOR = 2.53) that contracting pH1N1 would have a great impact on their daily life were more than twice as likely to intend to receive vaccination, compared with their counterparts. Participants who perceived the pH1N1 vaccine to be very effective in preventing pH1N1 were also more than twice as likely to intend to receive vaccination (AOR = 2.64). Finally, as compared with participants who thought it was difficult or very difficult to get vaccinated as suggested during the pandemic, those who did not perceive it to be very difficult were almost nine times (AOR = 8.97) and those who did not perceive it to be difficult at all were about 30 times (AOR = 30.72) as likely to intend to receive vaccination.

Discussion

International comparisons of vaccination intention

Of the 1079 participants in our national sample, 70.1% indicated that they intended to receive pH1N1 vaccination. This overall percentage is almost identical to 70.2% as reported by one study in Malaysia.25 By contrast, another survey in Asia among a sample of 301 adults in Hong Kong found that only 45% would take up vaccination if it was free.17 The proportion of the general population who intended to get vaccinated appeared to vary substantially across studies in different countries—e.g. 67% in Australia,26 61% in France,27 46–57% in the USA according to a synthesis of national polls28 and 22.2% in Greece.20 Hence, international research collaboration is warranted in the future to explore any such cross-national differences and their contributing factors.

The role of sociodemographic characteristics

Three sociodemographic characteristics, including gender, age and household income, remained significant in our final multivariate model. Males were more likely than females to intend to receive pH1N1 vaccination, as was reported in a Greek national study.20 By contrast, the effect of gender was not statistically significant in a number of pH1N1 studies in other countries, including Malaysia,25 Hong Kong21 and France.27 Therefore, more research is needed to confirm such gender differences and to explore their likely causes as they would have important implications for programme planning.

Regarding age, our results showed a U-shaped pattern of vaccination intention, with participants aged 25–44 years being less likely, whereas those aged 18–24 and ≥65 years being more likely to intend to be vaccinated. Those aged 15–17 years also had an increased likelihood, albeit non-significant. This age pattern may be largely attributed to Taiwan's national immunization programme in which the 13–24 age group was placed higher while the three age groups (i.e. 25–49, 50–64 and ≥65 years) were placed at the bottom of the recommended pH1N1 vaccination priority list,29 and the public was informed of such official advice through widespread media campaigns. Interestingly, although the elderly were the last priority on the list, they were still more inclined to receive vaccination, as has been found in prior research.27

Finally, participants with a mid-range household income had greater odds of intending to be vaccinated, compared with their more affluent counterparts. Given that pH1N1 vaccination was free to all residents in Taiwan, financial costs were not likely to play an important role in participants’ decision. Nonetheless, the wealthier participants may have more resources and better access to health-care services, thus not needing to rely on free vaccination as their primary measure of protection and hence being less inclined to be immunized. Additional studies are needed to explore the effects of income on vaccination intention and possible mechanisms.

Effects of theory-based health beliefs on vaccination intention

Four health beliefs concerning perceived severity, perceived benefits and perceived barriers were significantly associated with pH1N1 vaccination intention in our multivariate analysis. First, the HBM posits that people with higher perceived severity about a disease would be more likely to take preventive action, and as predicted, participants who agreed or strongly agreed that contracting pH1N1 would have a great impact on their daily life were more likely to intend to be vaccinated. Interestingly, perceived susceptibility was not predictive of pH1N1 vaccination intention in the final model, suggesting that perceived seriousness outweighs perceived likelihood of contracting the disease in people's decision to be immunized against pH1N1. Further, participants who perceived the pandemic in Taiwan to be much more severe than that in other countries were also more likely to intend to receive vaccination. To our knowledge, such perceived severity concerning pH1N1 relative to other countries has not been reported in previously published literature. Taken together, these findings highlight the importance of convincing the public of the seriousness of a novel disease when promoting the recommended preventive behaviour. Our results also underscore the need for transparency by public health authorities when communicating with the public. If the pandemic is more severe, compared with other countries, candid and up-to-date information should be disclosed and not concealed, as this study found that such comparative severity may help increase intention to comply with official recommendations.

Regarding perceived benefits, participants who considered pH1N1 vaccination very effective in preventing pH1N1 were more likely to intend to get vaccinated. Notably, if pH1N1 vaccination was only considered effective, its effect on vaccination intention was non-significant. Like perceived severity discussed above, for vaccination behaviour, perceived benefits also appeared to have a higher threshold in order for these psychological determinants to prompt a behavioural response or intention. As such, future campaigns to promote vaccination should pay particular attention to providing evidence-based information and clear explanation to the public concerning the effectiveness of any such vaccination.

Finally, as indicated by the sizes of the regression coefficients in our final multivariate model, perceived barriers had by far the largest effect on participants’ intention to receive pH1N1 vaccination. Our results are consistent with reviews of prior HBM-based studies in which perceived barriers have also been identified to be the strongest predictor of preventive health behaviour.30,31

Reported barriers to receiving vaccination

Ancillary analyses (data not shown) were performed to examine the top three barriers to receiving pH1N1 vaccination as reported by the 323 participants who did not intend to get vaccinated. First, 213 participants (65.9%) cited concerns about the side effects of the pH1N1 vaccine. Second, 157 participants (48.6%) reported lack of confidence in the quality of the pH1N1 vaccine. Last, 71 participants (22.0%) also identified inconvenience as a barrier. Further qualitative research may explore what factors contribute to these perceived barriers and how to best address them to increase compliance with official recommendations.

Limitations and future directions

This study has limitations that could be addressed in future research. Conducted before any pH1N1 vaccine was available in Taiwan, this study could only document people's intention, instead of actual vaccination behaviour. Thus, future research may compare the psychosocial determinants of vaccination intention vis-à-vis actual behaviour and seek to identify the crucial factors that prompt people to proceed from vaccination intention to action. Also, this study only examined psychosocial predictors based on the HBM. Future research can explore other predictors, including perceptions of descriptive norms, injunctive norms, modeling and social reinforcement, as suggested by additional behaviour change theories. This survey did not inquire about history of receiving seasonal influenza vaccine and such experience might also influence pH1N1 vaccination intention. Lastly, lacking data on non-participants, no demographic comparisons between participants and non-participants could be made to assess external validity. However, since our sample distribution was comparable with that of Taiwan's national census data, it is arguable that potential threats to the study's external validity are minimal.

Conclusions

Conducted during the 2009 pandemic, this national study in Taiwan is among the first few investigations examining theory-based psychosocial variables in association with pH1N1 vaccination intention in the general population. Our findings suggest that vaccination promotion programmes need to focus on convincing the public of the seriousness of the disease as well as the effectiveness of the vaccine in preventing the disease. Above all, efforts should be made to understand and minimize perceived barriers, including concerns about its side effects and lack of confidence in its quality. These specific and modifiable health beliefs have practical implications for prevention and control of emerging infectious diseases. Finally, cross-national comparisons are needed to examine whether these psychosocial determinants of vaccination intention apply to various populations in different cultures.

Funding

This work was supported by the National Science Council, Taiwan (grants NSC 98-2621-M-002-021-, NSC 99-2621-M-002-010-, and NSC 100-2621-M-002-010- to J.-H.H.).

Key points

  • The majority of people in Taiwan intended to be vaccinated against pH1N1.

  • Perceiving pH1N1 to be much more severe in Taiwan than in other countries increased vaccination intention; those who perceived that contracting pH1N1 would have a great impact on daily life were also more inclined to get vaccinated.

  • Perceiving pH1N1 vaccine to be very effective increased vaccination intention.

  • Perceiving no difficulty being vaccinated increased pH1N1 vaccination intention.

  • These results highlighted the importance of minimizing perceived barriers while convincing the public of the seriousness of the disease and effectiveness of vaccination when promoting vaccination programmes.

Acknowledgements

This research was supported by the National Science Council, Taiwan. The sponsor had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review and approval of the manuscript; or the decision to submit the manuscript for publication. The authors also thank the participants for their close attention and candor in responding to this national survey.

References

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