Vaccination is one of the most effective public health measures to control and manage infectious diseases (Hickler et al, 2015), as has been demonstrated by the eradication of smallpox and the control of poliomyelitis (polio). Vaccination is again forming a key aspect of the control of SARS-CoV-2, both within the UK and globally, alongside other public health measures, which include identification of those infected and isolation of these individuals and their contacts. Phillis (2020) described how two vaccines (Oxford AstraZeneca's adenovirus-vectored vaccine and Novavax's protein adjuvant vaccine) were developed and tested.
The frequent mutation (antigenic drift) of the influenza virus requires an annual vaccination programme of the vulnerable population, which was previously restricted to older people, but was extended to all adults with long-term conditions (Joint Committee on Vaccination and Immunisation (JCVI), 2020). In 2020, the programme was extended further to everyone over 50 years of age where there was vaccine availability (NHS England, 2020). A phased extension of the seasonal influenza vaccination programme to children began in 2013 (JCVI, 2020) to minimise vector transmission to the vulnerable older adult population. The autumn of 2020 (September–November) was the first time that the seasonal influenza vaccination rates in England for people aged 65 years and older exceeded the World Health Organization (WHO) target of 75% uptake at 77%, with uptake levels in previous years fluctuating between 71% and 75% (Nuffield Trust, 2021). Yet, despite the annual seasonal influenza vaccination programme, the influenza mortality rate remains notable and has varied over the past 5 years (2015/16–2019/20) between 7371 (2015/16) and 22 087 (2017/18) (Public Health England (PHE), 2020a).
Although a substantial majority of the UK population holds positive views about the COVID-19 vaccine (Freeman et al, 2021), the undoubted benefits of vaccination have spurred interest as to why some people decline a vaccination when it is offered even when it is cost free to the individual receiving the vaccination. ‘Vaccine hesitancy refers to delay in acceptance or refusal of vaccination despite availability of vaccination services’ (MacDonald and SAGE Working Group on Vaccine Hesitancy, 2015:4163). Vaccine hesitancy spans a continuum between two extremes of those who accept all vaccines with no doubts and those who refuse all vaccines with no doubts, with vaccine-hesitant individuals falling between these extremes (MacDonald and SAGE Working Group on Vaccine Hesitancy, 2015). The acceptance of a vaccination (that is, vaccine uptake) is an outcome behaviour arising from a complex personal decision-making process that may be influenced by many factors, with vaccine hesitancy being context specific and varying across time, place and different vaccines. An additional complexity is that research studies report vaccine hesitancy in different ways, such as vaccine refusal/decliners/acceptance, vaccination intention/likely acceptance and vaccine uncertainty, reflecting the studies' approaches to measurement.
Vaccine hesitancy is of particular relevance to community nurses regarding the acceptance of the annual seasonal influenza vaccination, as well as the acceptance of the pneumococcal and herpes zoster vaccinations among their older clients. More recently, vaccine hesitancy has been a concern regarding the implementation of the whole-population COVID-19 vaccination programme, especially with its two-dose regimen, which may be associated with the risk of drop-outs after the first dose. This article is one of two and will focus on what is known about vaccine hesitancy; the follow-up article will focus on evidence-based strategies to address vaccine hesitancy.
MacDonald and SAGE Working Group on Vaccine Hesitancy (2015) reviewed various potential explanatory models of vaccine hesitancy and concluded that the 3C model of the WHO EURO Vaccine Communications Working Group summarised the key components of vaccine hesitancy, namely, confidence, complacency and convenience, and was used to inform the WHO Global Vaccine Action Plan (WHO, 2012). Confidence reflects trust in the vaccine (safety and effectiveness), complacency reflects perceived risk of the infection and self-efficacy, and convenience reflects accessibility (physical availability, health literacy and socio-cultural appropriateness). Additionally, MacDonald and SAGE Working Group on Vaccine Hesitancy (2015) proposed a matrix of determinants of vaccine hesitancy across three domains – namely, context (historical, socio-cultural, environmental, health system/institutional, economic and political factors), individual and group (personal perception of the vaccine and social/peer environment), and vaccine – and vaccination-specific issues-to guide the development and testing of interventions to improve vaccination uptake.
Factors associated with vaccine hesitancy
The WHO commissioned a systematic review due to concern related to influenza vaccine hesitancy across the globe, which was particularly evident during the 2009–2010 H1N1 pandemic (WHO, 2016). The review included 470 empirical papers published between 2005 and 2016 and analysed their findings in terms of potential barriers in an attempt to understand decision making, drawing on the theory of planned behaviour (Ajzen, 1991). The review identified nine psychological barriers to decision making around vaccination:
- Utility (a function of risks and benefits of the vaccination)
- Risk perception (low risk perception specific to influenza and general ill health and high risk perception of vaccine-related adverse events)
- Social benefit (belief that being vaccinated protects others)
- Subjective norm (belief about what others do)
- Lack of perceived behavioural control
- Negative attitude about vaccine effectiveness
- Past behaviour (previous vaccination behaviour)
- Experience of sickness preventable by vaccine
- Lack of knowledge about illness and vaccination.
Physical health barriers included unhealthy lifestyles, such as high alcohol consumption, smoking, low physical activity and high BMI. The review also identified four contextual barriers:
Vaccine hesitancy is associated with a range of sociodemographic and contextual variables
- Access issues (including perceived inconvenience)
- Low interaction with healthcare system (including lack of regular source of healthcare)
- Lack of cues to action (direct recommendation by trusted health professional or relative)
- System factors (large size of health facility and socio-economic sensitivity).
Various sociodemographic factors also appeared to be barriers to vaccine uptake and included age (higher age was a barrier), living alone and being unmarried, but study results regarding ethnicity and gender were inconclusive.
Two reviews have been published after the WHO review. Larson et al's (2014) systematic review of papers published between 2007 and 2012 included 1164 empirical papers building on MacDonald and SAGE Working Group on Vaccine Hesitancy (2015) proposed a matrix of determinants of contextual influences, vaccine and vaccination-specific issues and individual/group influences. The contextual issues found to impact vaccine hesitancy included income level/socio-economic status and level of education, with media messages both increasing hesitancy and promoting vaccine uptake. The vaccine- and vaccination-specific issues found to impact vaccine hesitancy included time and accessibility. The individual and group influences found to impact uptake included vaccination as a social, familial and workplace norm, beliefs about health (good health knowledge, self-efficacy, positive health behaviours) and knowledge/awareness of vaccine-preventable disease. Larson et al (2014) noted that there was no universal algorithm for vaccine hesitancy because the impact of different factors and their relative strength of influence is complex and context specific, varying across place, time and vaccine.
The European Centre for Disease Prevention and Control (ECDC) (2015) published a rapid literature review comprising 29 papers reporting studies conducted in the EU and EEA countries between 2004 and 2014 to inform a strategy to motivate a generally vaccine-hesitant European population. Of these, 18 studies focused on different vaccines (10 seasonal influenza vaccines, four HPV vaccines, two 2009 pandemic influenza A (H1N1) vaccines, one herpes zoster vaccine and one pertussis vaccine), six focused on all types of vaccines and six focused on childhood vaccines. The most common contextual issues identified in this review were conspiracy theories/myths and religious fatalism, while the most common individual/group influences were the belief that vaccines were unsafe and could cause severe disease or side effects, perceived low risk of the preventable disease and the absence of the social norm to take a vaccination. The two most common vaccine-specific issues were lack of medical need for the vaccine and accessibility relating to timing and availability of vaccines. A global survey (n=65 819) conducted in 2015 across 67 countries found that the European region reported the lowest confidence in vaccine safety, with France being the least confident (Larson et al, 2016). These issues are evident in the roll-out of the COVID-19 vaccines within the EU and have unfortunately been accidentally ‘confirmed’ by some politicians, local regulators and the media (BBC, 2021).
Vaccine hesitancy globally
An analysis of data from the WHO/UNICEF Joint Reporting Form between 2015 and 2017 found that vaccine hesitancy was common (in more than 90% countries), with reasons varying by country income level and WHO region (Lane et al, 2018). More recently, research has focused on COVID-19 vaccine hesitancy. Su et al's (2020) discussion paper argued the imperative for a nuanced understanding of vaccination decliners (sometimes labelled non-adopters), with increasing evidence that intentions to accept a COVID-19 vaccine vary widely, with vaccine hesitancy threatening global health (WHO, 2019) and the ending of the pandemic. Su et al (2020) noted that vaccination decliners comprise a diverse group of vaccine conspirators, vaccine hesitant and vaccine uninformed, whose information needs are very different and require tailored communication to be met. The need for a nuanced approach to public health messaging is confirmed by a recent Australian longitudinal survey (n=3061) (Edwards et al, 2021).
A discrete choice experiment (n=1883) conducted in six Chinese provinces tested seven attributes: vaccine effectiveness, vaccine side effects, accessibility to vaccines, number of doses, access to vaccination sites, duration of vaccine protection and proportion of acquaintances vaccinated (Leng et al, 2021). All seven attributes significantly influenced COVID-19 vaccination decisions, with three attributes (vaccine effectiveness, side effects and proportion of acquaintances vaccinated) being more important. However, there was considerable preference heterogeneity, with the following groups being more likely to be vaccinated: older people; the less educated; and those with lower income, higher trust in the vaccines and perception of higher infection rates.
A large survey of a random sample of 13 426 living in 19 countries representing 50% of the world's population conducted in June 2020 found large variations in the likely acceptance of the COVID-19 vaccine (Lazarus et al, 2021). Those reporting higher trust levels with government-sourced information were more likely to accept a COVID-19 vaccine and were also more likely to heed employer guidance regarding vaccination. This suggests that communication strategies need to address misinformation and build trust in vaccination using formal and informal community leaders.
An online survey (Malik et al, 2020) in the US in May 2020 found that 67% (n=450/672) of Americans would accept a COVID-19 vaccine, but there were clear demographic variations, with higher acceptance rates among males (72%), older adults (over 55 years; 78%), Asians (81%) compared with other racial and ethnic groups, and college and/or graduate degree holders (75%). This study also compared seasonal influenza and COVID-19 vaccination behaviours and found that those who did not complete high school had a very low influenza vaccine uptake (10%), while 60% of the same group reported that they would accept the COVID-19 vaccine. The unemployed reported lower influenza vaccine uptake and lower COVID-19 vaccine acceptance when compared with those employed who were or retired. Black Americans reported lower influenza vaccine uptake and lower COVID-19 vaccine acceptance than all other racial groups. There were also regional differences, with New York and Chicago reporting less than 50% COVID-19 vaccine acceptance.
Online misinformation is widespread in the US and the UK, and its impact was tested in an intention randomised controlled trial (Loomba et al, 2021) (US: intervention group=3001, control group=1000; UK: intervention group=3000, control group=1000). In June 2020, the US had a 34.2% acceptance rate, but there were continuing falls in intention to be vaccinated. Recent misinformation induced a decline in intention to be vaccinated of 6.2% in the UK and 6.4% in the US among those who stated that they would definitely accept a vaccine. Some sociodemographic groups were differentially affected by exposure to misinformation relative to factual information. In the US, females were less robust to misinformation than males when considering vaccination intention to protect others, as were those from lower income groups. In the UK, the unemployed were more robust to misinformation than the employed. There was no evidence that those who used social media frequently were more susceptible to misinformation in both countries. More scientific-sounding misinformation had a greater impact on vaccination intent (Loomba et al, 2021).
The potential impact of the experience of different rates of COVID-19 was explored in a longitudinal study of 2267 Italian respondents (Caserotti et al, 2021). This study's findings illustrated how the intention to be vaccinated (both influenza and COVID-19 vaccines) was related to and tracked risk perceptions during the first wave of the COVID-19 pandemic in Italy.
Vaccine hesitancy in the UK
A large age-stratified retrospective cohort study of more than 3 million GP ‘at risk’ adult patient records from 2011–2016 explored factors associated with seasonal influenza vaccination (Loiacono et al, 2020). The study found significant differences in the seasonal influenza vaccination uptake by ethnicity (higher uptake among whites than blacks), sex (higher uptake among women than men), age (higher uptake among older adults than younger ones), socio-economic deprivation (lower uptake with greater socio-economic deprivation), and comorbidities (higher uptake among younger adults with diabetes and older adults with respiratory disease and low uptake among adults with morbid obesity, irrespective of age). There were also notable differences in vaccine uptake across practices, suggesting that the quality of primary care provision also varies.
Among the 32 361 UK adults participating in the University College London COVID-19 Social Study, 14% reported an unwillingness to receive a vaccine for COVID-19, and an additional 23% were unsure, with 16% of the sample reporting high levels of mistrust about vaccines across one or more domains (Paul et al, 2021). These distrustful attitudes were higher among those from ethnic minority backgrounds, with lower levels of education, lower income levels, poor knowledge of COVID-19 and poor compliers with Government COVID-19 guidelines. The largest predictors of both COVID-19 vaccine uncertainty and refusal were low-income groups (<£16 000 a year), having not received an influenza vaccine during the past year, poor adherence to COVID-19 Government guidelines, being female and living with children. Intermediate-to-high levels of mistrust of vaccine benefit and concerns about future unforeseen side effects were the most important determinants of both uncertainty and unwillingness to vaccinate against COVID-19. Thus, there is evidence that groups most vulnerable to falling ill and dying of COVID-19 (those from ethnic minority backgrounds and who have lower incomes) (PHE, 2020b) have more negative attitudes towards vaccines and are less willing to vaccinate against COVID-19.
In another recent survey (Freeman et al, 2021) of 5114 UK adults participating in the Oxford OCEANSII, 28.3% of participants expressed some hesitancy (11.7% strongly hesitant and 16.6% unsure). Vaccine hesitancy was associated with younger age, female gender, lower education, lower income, black and mixed ethnicities, not being single or widowed, not being a homeowner, not being employed full-time or retired, a change in working and having a child at school. In this study, hesitancy was explained by beliefs about the collective importance of vaccination and mistrust about a COVID-19 vaccine regarding low efficacy, side effects and speed of development, while positive views about healthcare increased enthusiasm for a COVID-19 vaccine.
An online survey (Royal Society of Public Health, 2020) of a representative sample of 2076 UK adults conducted on 4–6 December 2020 also found higher vaccine hesitancy among those from ethnic minority backgrounds. While 76% of the sample intended to take a COVID-19 vaccine if advised to do so by a health professional, only 57% (n=199) of those from ethnic minority backgrounds were likely to accept a COVID-19 vaccine compared with 79% of white respondents. Vaccine hesitancy was highest among those of Asian ethnicity, of whom 55% reported that they were likely to accept a vaccination. Over one-third (35%) of those from ethnic minority backgrounds reported that they would likely change their minds and take a vaccination if they were given more information by their GP about its effectiveness, which was almost twice as many as the 18% of white respondents who were initially unwilling. These findings echoed those of Bell et al's (2020) online survey of 1252 parents and guardians, most of whom reported that they would accept a vaccine for themselves (55.8%) and their children (48.2%). Those who were black, Asian, Chinese or of mixed or other ethnicity were almost three times more likely to reject a COVID-19 vaccination for themselves and their children than white British, white Irish and other white respondents. Those from lower-income households were also more likely to reject a COVID-19 vaccination. Hesitancy was related to vaccine safety and effectiveness concerns, low perception of risk, being previously infected and the need for transparency to make informed decisions.
Vaccine hesitancy among health professionals
Vaccine hesitancy among NHS staff is a concern, with variable uptake both across and within different NHS trusts reported in the media (Clover, 2021). Dube (2017) noted how vaccine confidence is fragile and that belief in vaccination is not always matched by trust in vaccine safety. It is important to understand health professional vaccine hesitancy because this hesitancy can cascade into their practice, not only because they may become vectors for COVID-19, but also because, if a healthcare professional is not confident about vaccination themselves (safety, effectiveness and importance of vaccination), they are unlikely to address the fears of hesitant patients. This echoes Zhang et al's (2011) survey of 522 UK nurses, which found that vaccinated nurses were more likely to recommend vaccination to their patients, and that there is a relationship between knowledge, risk perception and vaccination behaviours among nurses. Similar findings were reported regarding H1N1 vaccination and knowledge, risk perception and prior vaccination behaviour (Zhang et al, 2012a). Zhang et al (2012b) found that nurses who had never been vaccinated in the past 5 years had lower knowledge and risk perception, especially relating to personal vulnerability, but nurses' vaccination behaviour was complex. A more recent survey of 1205 Hong Kong nurses during the COVID-19 outbreak in March/April 2020 found sub-optimal levels of both influenza and COVID-19 vaccination intentions (49% and 63%, respectively) (Kwok et al, 2021). In this study, influenza vaccination intention was associated with more vaccine confidence, more collective responsibility and less complacency, constraints and calculation, as proposed in the 5C model to vaccination (Betsch et al, 2018), while COVID-19 vaccination intention was associated with younger age, more confidence, less complacency and more collective responsibility.
Conclusion
Vaccine hesitancy is a concern both globally and within the UK, despite the UK having one of the lowest levels of vaccine hesitancy. In the UK, there are significant levels of vaccine hesitancy across particular ethnic and socio-economic groups, which need to be addressed if the whole-population COVID-19 vaccination programme is to be successful and, importantly, to protect those at greatest risk from SARS-CoV-2 (PHE, 2020b). The benefits of addressing the attitudinal and behavioural barriers to COVID-19 vaccine hesitancy can be taken forward to addressing annual seasonal influenza vaccine hesitancy. Addressing vaccine hesitancy both in the general population and among health and care staff is a public health imperative.
Key Points
- Vaccination is an important and effective public health intervention
- Vaccine hesitancy refers to delay in acceptance or refusal of vaccination
- Vaccine hesitancy is associated with a range of sociodemographic and contextual variables
- Beliefs, self-efficacy, trust and accessibility to vaccines also affect vaccine hesitancy
CPD reflective practice
- List the concerns that your patients may have about the seasonal influenza vaccine and the COVID-19 vaccine. Are they the same concerns?
- Why might people you know or patients refuse a vaccination?
- What is the science underpinning a COVID-19 vaccine?
- What is the process by which a COVID-19 vaccine is approved by the Medicines and Health products Regulatory Authority?