Background
A vaccination against human papillomavirus (HPV) was introduced in the UK in 2008. The vaccination is delivered primarily through schools and is recommended for girls aged 12 to 13 years old (in school Year 8). Since the introduction of the vaccine, HPV immunisation programmes have been implemented in 64 countries nationally, with an estimated 118 million females targeted [
1].
In the UK, uptake of the vaccination is high, with 87% of girls receiving at least one dose of the vaccine in 2015/2016 [
2], although there is considerable variation in uptake across the country, ranging from 68% in Brent, to 97% in Sunderland, and as high as 100% in areas with small populations [
2]. Furthermore, ethnic inequalities in uptake have been consistently documented, which appear to be independent of deprivation [
3,
4].
It is important that we devise approaches to improve uptake of the vaccination. In the UK and elsewhere in the world, there is evidence of assortivity of sexual mixing (sexual partnerships being more likely between people within the same ethnic group) [
5,
6]. Whilst high uptake of the vaccine should offer herd protection to those who remain unvaccinated, such patterns of sexual mixing may exacerbate disease inequalities as unvaccinated individuals who engage in sexual partnerships with others who have not been vaccinated will not benefit from herd immunity.
One potential way of encouraging healthy behaviours, such as vaccination, is through the use of incentives, which have been successfully used to encourage behaviour such as attending non-smoking clinics, attending check-ups or completing screening [
7,
8], although much of the research in this area has been conducted in the United States. Defined as a direct or indirect reward for attaining a goal [
9], types of incentives may include the provision of gifts or prizes, lotteries, free or reduced price goods or services, or financial rewards such as cash, or cash-like rewards, such as shopping vouchers [
10,
11]. Financial incentives have been found to be around 1.5 to 2.5 times more effective at encouraging healthy behaviours than no intervention or usual care [
11]. In the context of vaccination, financial incentives have been used to encourage vaccination receipt, with varying success [
12‐
15].
However, opinion on the use of financial incentive interventions varies widely; while some believe such incentives play an important role in the promotion of health behaviours, they can be viewed as a form of bribery or coercion, and are perceived by some to undermine individual autonomy [
16,
17]. Financial incentives have been found to be less acceptable than other methods of behaviour change, such as education or peer support [
18], although acceptability has been shown to increase with reported effectiveness [
19]. If the financial incentive is considered to be an effective way to change behaviour and to be cost-effective, if it provides benefits to individuals and wider society, and is considered to be fair, then it is also more likely to be viewed as acceptable [
20]. Furthermore, financial incentives in the form of food or shopping vouchers are viewed as more acceptable than cash incentives [
17,
19], as it reduces the chance that the incentive is used to engage in negative health behaviours such as tobacco use or alcohol consumption [
17].
These ethical concerns, combined with the fact that vaccination is not mandatory in the UK, suggests that incentivising vaccine receipt in itself is not an acceptable option for increasing HPV vaccination rates. An alternative option which has not previously been explored is incentivising the return of vaccination consent forms. This is an approach which has previously been recommended by adolescents, as a way to increase school-based vaccinations [
21]. In practice, individuals under the age of 16 are usually required to have consent from a person with parental responsibility in order to receive a vaccination [
22], although they may legally consent for themselves [
23]. This is variably implemented. The HPV vaccination consent process involves girls delivering information about the vaccination and a consent form to their parent
1. Parents are asked to give their child the completed consent form to return to the school, regardless of whether they are providing consent or refusing vaccination. The number of consent forms that are returned, for school-based vaccinations, has been shown to be improved if non-responsive parents are prompted with a second consent form [
24]. Similar prompts have also been found to be effective at improving consent form return for HPV vaccination; it has been suggested that around 60% of HPV vaccination consent forms are returned to schools, unprompted [
25]. Of the remaining 40%, half of these consent forms will be returned, consenting to vaccination, if followed up by a telephone call from an immunisation nurse [
25]. This suggests that by increasing consent form return rates, vaccination uptake rates should show a concomitant increase.
Between July 2016 and January 2017, we conducted a randomised feasibility trial of an adolescent incentive intervention to increase HPV vaccination uptake by incentivising HPV vaccination consent form return. The key objectives of the trial were to assess the feasibility of a future randomised controlled trial (RCT) and to generate proof of concept evidence of the effect of the intervention on both consent form return and vaccination uptake, as well as any unintended consequences of the intervention, mechanisms of action and incentive acceptability [
26,
27].
As with any intervention, successful implementation depends not only on the feasibility, but also on the acceptability. Acceptability is a necessary but not sufficient condition for intervention efficacy [
11] and reflects “the extent to which people delivering or receiving a healthcare intervention consider it to be appropriate, based on anticipated or experienced cognitive and emotional responses to the intervention” [
11]. We therefore collected qualitative data assessing the acceptability of the incentive, as part of a process evaluation embedded into the feasibility trial. In this paper, we present this qualitative data and aim to assess the acceptability of the incentive for adolescent girls, their parents, and participating school staff.
Discussion
The purpose of this paper was to assess the acceptability of an incentive intervention to encourage the return of HPV vaccination consent forms for adolescent girls, their parents and participating school staff members. The aim of the incentive was to indirectly increase HPV vaccination uptake by improving the number of consent forms returned in schools. Our analysis of free-text questionnaire data identified a mix of views from girls and parents regarding the acceptability of the incentive; Positive, negative and ambivalent responses were expressed by girls and their parents, and both these groups of participants held misconceptions about the nature of the incentive. The analysis of interview data with school staff members also highlighted a mix of opinions on the acceptability of the incentive, which included perceptions of effectiveness and ethics.
Sekhon, Cartwright and Francis [
29] have proposed a theoretical framework that can be used to guide the assessment of acceptability of interventions from both a recipient and deliverer’s perspective. The framework comprises seven component constructs to assess acceptability and we have interpreted our results using these constructs as a guide; Affective attitude (how an individual feels about the intervention) was relatively positive for most school staff members, who believed the intervention was a good idea and felt that girls had responded positively. In terms of the ethicality of the intervention (the extent to which the intervention has a good fit with the individual’s value system) one school staff member questioned the appropriateness of using an incentive and a number of parents and girls reported feeling as though the incentive was being used as a bribe. However, this view was often linked to misconceptions about the nature of the incentive. Related to this, intervention coherence (the extent to which the individual understands the intervention and how it works) was not always high, as some girls and parents believed that the incentive was dependent on vaccine receipt, not consent form return. With regard to perceived effectiveness, school staff members were divided. However, those that felt it had been ineffective did so because of the high form return rates they ordinarily have at their school, not due to the design of the intervention. Many girls and parents felt that an incentive was an effective way to encourage form return. The constructs, opportunity costs (the extent to which benefits, profits or values must be given up to participate), burden, and self-efficacy, were not discussed by participants in relation to the incentive itself, suggesting they play less of a role in the perceived acceptability of the incentive in this context. Based on this framework the incentive intervention was found to be moderately acceptable to both the recipients (girls and parents) and deliverers (school staff members
3) of the intervention, although it is evident that some improvements could be made to improve overall acceptability and clarity of its purpose.
The findings support previous research which has found that financial incentives may be viewed as a bribe or form of coercion [
16,
17], a concern that a number of participants expressed. However, this concern was often based on the misconception that the incentive was dependent on vaccination receipt, rather than consent form return. This is an important finding, as the concept of the intervention is called into question if participants misunderstand how the incentive works. It is therefore vital that communication about the nature of the incentive is clarified and/or simplified. This may consequently improve acceptability of the incentive. This might be achieved by amending the wording of the letters given to girls via the schools or by clarifying the verbal instructions tutors are requested to deliver to girls in their tutor groups. Future qualitative research with girls may be beneficial to help us understand specifically which part of the information is misleading or easily misinterpreted, and to identify how we can better communicate the details of the incentive.
As previously discussed, incentivising vaccination receipt has ethical implications that mean it is not likely to be an acceptable option for improving HPV vaccination rates [
16‐
18]. Our findings demonstrate that incentivising consent form return instead of vaccine receipt, is a moderately acceptable form of intervention for those receiving and delivering the incentive, which may have implications for the types of interventions used, not only within the HPV vaccination context, but potentially within the context of other school-based vaccinations. However, a number of improvements would be required in order to increase the acceptability of the incentive.
Furthermore, our findings suggest that for some girls, the incentive could lessen feelings of worry and fear about the vaccination, and make the process more positive. Experiencing fear and anxiety about the vaccination is common for adolescent girls within a school context and in some instances this can result in vaccination refusal [
30]. The use of the incentive may therefore have the potential to improve vaccination uptake, not only by increasing the number of forms that are returned consenting to vaccination, but by lessening the fear experienced by some girls who might otherwise refuse the vaccination at the point of receipt. Bernard et al. [
30] also found that parents were often aware of their daughter’s fear about the vaccination, which may potentially act as a barrier to providing consent. Lessening fear amongst girls, via the use of the incentive, may also help to mitigate this situation and help to facilitate consent provision from the point of view of the parent.
However, it is important to acknowledge the ethical implications of delivering an intervention such as this. Although the potential for serious harm appears to be relatively low, there are a number of issues that need to be considered. There may be the potential for girls to become distressed if they do not win the prize, and the results show that for some girls this was the case. Furthermore, girls may become distressed if their parent is unwilling to sign the form. Relatedly, it is important to consider if such disappointment may manifest into negative attitudes or behaviour towards prize winners. Other concerns include the possibility that some girls may forge their parent’s signature in order to be entered into the draw, or that parents may have grievances about the incentive being offered to girls, as opposed to parents, or about what the voucher is spent on. In order to identify whether such concerns are warranted and to assess the impact of such issues, further work with both girls and parents will be required.
Based on the coherence of participants’ responses with previously theorised aspects of intervention acceptability [
29], we feel confident that making improvements to the way in which the nature of the incentive is communicated would likely increase acceptability of the incentive. However, there is reason to remain cautious; five out of the six interviews conducted with school staff members were with those who worked at schools randomised to the incentive intervention arm of the trial. Schools in this arm may have had more positive attitudes towards the incentive, than those working in schools randomised to the standard invitation arm, due to observing the impact of the incentive in their schools. A further limitation is that only 17% of parents responded to the questionnaire. The views of these participants are therefore not representative of all parents who took part in the trial and there may be a response bias towards those who felt more strongly, or more negatively, about the intervention. Due to the low response rate, data collected from parents in both arms of the trial were interpreted together. We were therefore unable to compare differences in parental attitudes between trial arms, which is an additional limitation. Furthermore, there was weak inter-rater reliability for the coding of the parents data. However, all discrepancies were resolved through discussion before the coded data were interpreted. The acceptability of incentive interventions has been found to be dependent on the context in which the intervention is delivered [
31]. It is therefore important to be mindful that the incentive was trialled in only one context, in UK schools, and that the acceptability of the incentive may therefore differ if implemented in other settings, such as non-UK countries or outside of the school environment.