Introduction

In 2009 a new strain of the influenza A virus (H1N1) was recognised in Mexico and the USA, quickly spreading worldwide. On 11 June 2009 the World Health Organization declared the outbreak to be a pandemic.1 In England, whilst the disease was not as severe as initially anticipated, the pressure experienced within the healthcare sector was significant. This strain of pandemic influenza proved to be mild in most cases, but severe and sometimes fatal in a minority.2

Vaccines were developed as part of a global response to the pandemic. The two vaccines initially licensed for use in the UK were Pandemrix (GlaxoSmithKline), a one-dose schedule for most people, and Celvapan (Baxter), a two-dose schedule, reserved in the UK for persons unable to have Pandemrix.3

All 2009 H1N1 vaccines were shown to have an acceptable safety profile.4 However, at the time of the pandemic there was considerable media unease, in particular with regard to safety testing in pregnancy5 and also a possible link with Guillain-Barré syndrome and other rare complications.6 These concerns were articulated by the general population,7,8 and early surveys suggested that the intention by healthcare workers to be vaccinated was also low,9–11 presumably due to similar concerns. Similar patterns were seen internationally.12,13

Vaccinating healthcare workers has been shown in other healthcare settings to be a cost-effective way to reduce transmission and to protect the most vulnerable in the population.14 From the beginning of the pandemic vaccination campaign, frontline healthcare workers were prioritised for vaccination to protect not only themselves but also their patients and to maintain frontline medical services.15

The aim of this study was to determine what factors affected vaccination uptake among general practice healthcare workers in Shropshire County Primary Care Trust (PCT) in the UK.

Methods

Participants

The survey was aimed at all front line healthcare workers who were working in Shropshire County's general practices in June 2010 (defined as ‘those who had regular clinical contact with patients and who were directly involved in patient care’16). This group included GPs, practice nurses and healthcare assistants. Each practice manager or delegate was personally approached and asked if the practice would participate. All 45 practices agreed to take part.

Vaccination programme

The vaccination programme began in Shropshire County in November 2009. Practices were provided with vaccine for all eligible staff but were required to devise their own systems for vaccination.

Procedure

Questionnaires (marked with practice code but no further identifiers) were provided to each practice manager in June 2010 and distributed to front line members of staff, who were then asked to return them by post using pre-paid addressed envelopes. Practice managers of practices with the lowest return rates were reminded by telephone in September 2010.

As the survey was designed and conducted during the pandemic, the situation was still evolving and no pre-existing validated questionnaire was found for the purposes of this study. A questionnaire was designed, adapting questions previously used within the context of seasonal influenza where applicable,17,18 supplemented with customised specific H1N1 questions. The full questionnaire is provided as an appendix, available online at www.thepcrj.org. Questions were mainly yes/no or required the respondent to select from a list of options. Some sections had space for open answers. The questionnaire was designed to be as simple and short as possible, and was amended following piloting on 10 healthcare workers from a neighbouring PCT. No identifiable data were collected.

Outcomes

The primary outcome for analysis was pandemic influenza immunisation status in the 2009–10 influenza season.

Sample size

Based on an initial estimate of 750 frontline primary healthcare workers (from PCT figures) and assuming a response rate of 33%, 250 respondents would provide 80% power (and 95% confidence interval (CI)) to detect an increased odds ratio (OR) for acceptance of 3.5 for factors prevalent at 10%.

Ethical approval

Ethical approval was granted by the Birmingham, East, North and Solihull Research Ethics Committee on 26 April 2010.

Data analysis

All statistical analyses were undertaken in Stata/IC 10.0 software.

Basic descriptive statistics were used to describe uptake and distribution of characteristics and factors. Multiple logistic regression analyses (based on p >0.1 or logical confounders such as gender) were used to determine the most important factors associated with acceptance or refusal of vaccination among healthcare workers, including analysis by occupational group.

Although respondents were asked to rank answers in some questions, few people did so, therefore the analysis was based on total answers given rather than ranks.

Results

Demographics

Practice managers estimated that the number of frontline primary healthcare workers would be 427, although larger numbers of questionnaires were provided for distribution, of which 218 were returned. Each of the 45 practices returned at least one questionnaire. Thirteen of the replies were from staff whose job title as reported in the questionnaire did not fulfil the definition of ‘frontline healthcare worker’ and therefore were excluded. This left a total of 205 replies, giving a response rate of 48.0%. The demographics of the respondents are shown in Table 1. A large proportion of respondents (n=100, 48.8%) were aged 45–54 years and 130 (63.4%) were female; 108 (52.7%) were GPs and 116 (56.6%) worked part-time. Most (94.6%) were of white ethnicity and very few were current smokers. 73.4% had received an influenza vaccine the previous year. Twenty (10.0%) believed they had been infected with the pandemic H1N1 strain by the time they received the questionnaire.

Table 1 Participants' baseline characteristics
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Influenza and influenza vaccination uptake

One hundred and seventy-two respondents (83.9%) reported that they had been vaccinated against H1N1 (Table 2). Few demographic characteristics had an effect on vaccination uptake. In particular, age, gender, ethnicity and job title had no significant effect. Influenza infection prior to vaccination had a negative impact on uptake (adjusted OR 0.17, 95% CI 0.05 to 0.56) and previous vaccination against seasonal influenza was associated with increased uptake (adjusted OR 4.07, 95% CI 1.62 to 10.24). Pre-existing medical conditions had no impact on vaccination uptake.

Table 2 Factors affecting influenza vaccination uptake
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Attitudes to vaccination

Table 3 shows that there was a widespread belief that pandemic influenza was not more serious than seasonal influenza, although 57% of healthcare workers believed they were at risk of contracting pandemic influenza. Concerns were expressed about the risk of side-effects, in particular Guillain-Barré syndrome, and also about the use of adjuvants, especially thiomersal. However, the large majority of respondents felt they had adequate information and convenient access to vaccination and believed it to be effective. The greatest predictors of vaccination were believing the vaccine to be effective (OR 14.06, 95% CI 2.78 to 71.07) and believing vaccination was of personal benefit (OR 45.74, 95% CI 8.3 to 251.91) or of benefit to colleagues (OR 17.29, 95% CI 3.41 to 87.78). Those who were concerned about the adjuvant were least likely to accept the vaccination (OR 0.16, 95% CI 0.05 to 0.51). Those who received the pandemic vaccine were seven times more likely to accept future vaccines (OR 7.04, 95% CI 2.70 to 18.37).

Table 3 Summary of attitudes towards vaccination and their effect on uptake of vaccination
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When specifically asked, of those who accepted vaccination the most common reasons given were to reduce transmission to others (n=152, 88.3%) and to protect themselves (n=142, 82.6%). Of those who refused (n=33), the most common reason was concern about side-effects (n=19, 57.6%). Four respondents said they would have liked to be vaccinated but missed the opportunity, one had contraindications to vaccination, and two disliked needles. No respondents refused because of objections to immunisations in general or because they were not considered eligible.

Discussion

Main findings

Our sample of 205 healthcare workers included 108 GPs, which represents 53.2% of Shropshire's GPs (based on 2007 GP census statistics19). The vaccination uptake for pandemic influenza (83.9%) was significantly higher than the national (40.3%), regional (40.9%), and county averages (49.3%).20 Acceptance of vaccination was predicted by higher confidence in the efficacy of the vaccine and belief in the potential severity of pandemic influenza. Crucially, all respondents in this survey felt that access to vaccination was convenient, which may go some way towards explaining the higher uptake than seen elsewhere. This higher uptake, however, may also reflect a responder bias, since the PCT vaccination rate for healthcare workers overall was only 49%.20 This study may also reflect a national trend of higher vaccination in primary care than in secondary care in the UK.1 This contrasts with the USA where the highest uptake of voluntary vaccination has been seen in hospital settings, most notably paediatric.21

Strengths and limitations of this study

An accurate estimation of the size of the workforce in primary care is notoriously difficult,22 as indicated in this study by the difference between PCT- and practice-level estimates of the population to be targeted by the questionnaire. The response rate in this study was just under 50% of questionnaires issued, which is similar to the response rates obtained with other respiratory questionnaires.23 However, our study is likely to suffer from some degree of response bias as vaccine uptake was much higher than the official PCT figures,20 although the same uncertainty may exist regarding the denominator used in both estimates. Responders may well be different from the general population of healthcare workers and thus reasons/attitudes may not be fully generalisable. Non-responders may be more likely to have refused the vaccine and therefore their characteristics could be quite different from the responding ‘non-uptake’ group. However, it is not possible to predict in which direction this may affect the risk estimates. Furthermore, it should be cautioned that odds ratios could exaggerate the effect size compared with relative risk where outcomes are common. However, our results are generally consistent with other national and international studies of actual receipt of, and intention to receive, pandemic vaccine. In addition, very few of the factors were statistically significant, which may reflect both the sample size and the high uptake. However, our study investigated vaccination uptake only within GP practices, which is a different arena from the primary care figures collected nationally which include staff from many backgrounds with no clinical contact. This is the first detailed study of influenza vaccination purely in general practice in England.

Interpretation of findings in relation to previously published work

It is clear that the circumstances surrounding the influenza pandemic were different from seasonal influenza. Consequently, it is not known whether factors influencing uptake of seasonal influenza vaccination will be pertinent in the case of pandemic influenza vaccination. Reasons given for healthcare workers refusing seasonal vaccination in non-pandemic years have included fear of side-effects, fear that vaccination would cause influenza, lack of awareness of vaccine availability or usefulness, forgetting, and perceived low risk of contracting influenza.17,23 In contrast, wishing to prevent transmission, believing the vaccine is effective, and previous influenza vaccination are all predictors of future seasonal influenza vaccination in both healthcare workers24 and the general public.25 An online poll conducted by the Nursing Times early in the pandemic showed that intended acceptance of pandemic influenza vaccines was associated with receipt of previous seasonal influenza vaccines, perceived likelihood of being infected, and belief in the efficacy of influenza vaccine.26 This has been reinforced by a meta-analysis of actual vaccine uptake internationally27 whose conclusions correspond closely with the findings here, although there was a greater expression of concern about side-effects in our study, probably due to media coverage. It thus seems reasonable to conclude that important variables in seasonal vaccination translate into pandemic situations.

Interestingly, aside from official Department of Health reporting, there is still a lack of published work examining vaccination in healthcare workers in the UK, with only one study in primary care28 and one in secondary care currently available.29 The other UK study (in Scotland)28 indicated that male and older healthcare workers and those with chronic medical conditions were more likely to receive vaccine. None of these factors was significant in our study, but males tended to be more likely to receive vaccine.

Implications for future research, policy and practice

Our study again shows that receiving seasonal influenza vaccination predicts receiving pandemic influenza vaccination, and this predicts future intention to receive later seasonal vaccinations. This comes as no great surprise, perhaps, but our study once again emphasises the importance of attaining and maintaining high vaccination uptake. Whilst vaccine acceptance in this population was high, nationally the figures are still suboptimal. Respondents were significantly more likely to have had pandemic or seasonal influenza vaccination than both local and national figures.1 This is key since, by identifying ‘bright spots’ of high performance, lessons learned can be applied to a wider setting.30 Here and in secondary care19,25 the lesson seems to be that easy access and a clear and consistent message about the efficacy, necessity, and safety of vaccination increase vaccination rates. Ensuring healthcare workers receive the vaccination early in their career is likely to set a precedent for future vaccination; an attractive option would be the routine introduction of influenza vaccine at medical/nursing school. Some commentators have even called for the vaccine to become mandatory31 to mitigate against the consistently low rates of voluntary uptake. Although this study highlights some important areas for improvement in vaccine uptake, further qualitative work to obtain the views of non-responders might generate further insights.

Conclusions

This study shows that predictors of vaccination behaviour for pandemic influenza are very similar to those for seasonal influenza. Consequently effort should be made to instil the vaccination habit early in the careers of health care workers.