Parental attitudes to pre-pubertal HPV vaccination

Parental attitudes to pre-pubertal HPV vaccination

Vaccine 25 (2007) 1945–1952 Parental attitudes to pre-pubertal HPV vaccination Laura A.V. Marlow, Jo Waller, Jane Wardle ∗ Cancer Research UK Health ...

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Vaccine 25 (2007) 1945–1952

Parental attitudes to pre-pubertal HPV vaccination Laura A.V. Marlow, Jo Waller, Jane Wardle ∗ Cancer Research UK Health Behaviour Unit, Department of Epidemiology and Public Health, UCL, Gower Street, 2-16 Torrington Place, London WC1E 6BT, United Kingdom Received 31 October 2006; received in revised form 3 January 2007; accepted 11 January 2007 Available online 22 January 2007

Abstract Objectives: To determine the acceptability of childhood HPV vaccination and examine demographic, cultural, and psychosocial predictors of vaccine acceptance. Design: School-based survey. Participants: Questionnaires sent to 1205 mothers of 8–14-year-old girls. Responses from 684 were included in the analyses. Setting: Ten schools (seven primary, three secondary) in four areas of England. Results: Seventy-five percent of mothers would accept the vaccine for their daughter. Vaccine acceptance was higher in mothers who had experience of cancer in the family (OR = 1.61, CI: 1.14–2.29), had older daughters (OR = 1.15, CI: 1.04–1.27), perceived approval from husband/partner (OR = 14.51, CI: 6.15–34.25) and believed vaccine acceptance would be more normative (OR = 1.78, CI: 1.59–2.01). Having concerns about too many vaccinations (OR = 0.22, CI: 0.15–0.31) or vaccine side effects (OR = 0.37, CI: 0.28–0.50) and worry about increasing promiscuity (OR = 0.47, CI: 0.36–0.62) emerged as deterrents. The modal preferred age was 12 years. Endorsing vaccination at earlier ages was predicted by feeling able to discuss related topics, including sex, at younger ages (OR = 1.37, CI: 1.24–1.51) and concern about increasing promiscuity (OR = 0.61, CI: 0.47–0.78). Conclusions: Overall, there was a favourable response to HPV vaccination. Emphasising the widespread acceptance of the vaccine might promote acceptance further, as would information on immunological and social benefits of earlier vaccination. © 2007 Elsevier Ltd. All rights reserved. Keywords: Human papillomavirus; Cancer prevention; Parents

1. Introduction Human papillomavirus (HPV) infection of the genital mucosa is a common, sexually transmitted condition and there is now conclusive evidence for its role in the aetiology of cervical cancer [1]. Prophylactic vaccination against HPV has been shown to be highly effective [2,3]. The quadrivalent vaccine, Gardasil, has recently been licensed by the European Commission [4] and is recommended for girls of 11–12 years by the CDC [5]. It is therefore timely to investigate public attitudes towards HPV vaccination in the UK. HPV vaccination is expected to reduce lifetime cervical cancer incidence [6], and in countries with cervical screening ∗

Corresponding author. Tel.: +44 20 7679 6642; fax: +44 20 7813 2848. E-mail address: [email protected] (J. Wardle).

0264-410X/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2007.01.059

programmes, may ultimately reduce the required frequency of cytological testing and expose fewer women to the stress of abnormal test results, colposcopy, and treatment. However, for vaccination to be cost-effective, uptake must be high. Mothers of adolescents in the US have been shown to be enthusiastic about HPV vaccination (see Zimet [7] for a review). Qualitative research with British mothers suggests they have concerns about vaccination in early puberty, the sexually transmitted nature of the virus, and possible harm from vaccinations [8]. In contrast, a survey of parents from Manchester schools found more than 70% were positive about HPV vaccination, although this conclusion was tempered by a low survey response rate (22%) [9]. Age of vaccination is an important issue, because for maximum effect the vaccine needs to be given in early puberty and certainly before the onset of sexual activity. However some parents

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Table 1 School characteristics School description Guildford (suburban)

Norfolk (rural)

Lambeth (inner city)

Nottingham (inner city)

Community Community VA Catholic Community Community Community Community VA Anglican Community Community Community

Secondary Primary Primary Secondary Primary Primary Secondary Primary Primary Secondary Primary

Percentage eligible for free school mealsa

Percentage Ethnic minoritya

Questionnaires returned (%)

3% 3% “Average” “Low” 2% 2% “Just over 50%” 23% 39% 50% 25%

10% “Low” “Mainly white” 2% 3% 0% 71% 62% 55% Low Low

222 (54%) 61 (69%) 40 (63%) 152 (70%) 37 (64%) 31 (76%) Withdrew 14 (45%) 24 (32%) 57 (44%) 45 (54%)

NB. Community schools are government funded and have no eligibility criteria. Voluntary aided (VA) schools are part-funded by religious groups and have their own eligibility criteria. a Figures were obtained from school inspection reports (http://www.ofsted.gov.uk).

are reluctant to consider their young adolescent daughters to be nearing their sexual debut, and express concern that vaccination could appear to condone early sexual activity [8,10]. The present study examined vaccine acceptance in mothers of 8–14 year olds to establish: (i) rates of HPV vaccine acceptance, (ii) the age at which mothers believe the HPV vaccine should be administered, (iii) attitudes towards HPV vaccination, and (iv) demographic and attitudinal predictors of vaccine acceptance and earlier vaccination age.

2. Materials and methods 2.1. Participants Participants were mothers with at least one daughter in school years 4–9 (ages 8–14). Convenience sampling was used to select four locations in England representing inner city, suburban, and rural areas (see Table 1) to ensure a range of parental backgrounds. Lists of all primary and secondary schools in these education authority areas were obtained. The largest secondary school and two primary schools were selected within the three areas (Guildford, Norfolk and Lambeth). In Nottingham, only one primary school was selected because we had reached the school recruitment target. The Head Teacher of each school was contacted and all 11 agreed to participate. One school withdrew from participation before data collection for reasons unrelated to the project. 2.2. Methods and measures Participants were asked to read brief information about HPV (see Appendix A) before completing the questionnaire. Intention to vaccinate was operationalised with the question: ‘If your daughter were invited to have the HPV vaccination, would you agree to her having it sometime soon’. Responses were on a 5-point scale (definitely not, probably not, not

sure, yes probably, yes definitely). The earliest age at which mothers thought girls should be vaccinated against HPV was assessed by asking them to identify an age from 8 or younger to 15 or older. Potential predictors were derived from social cognition theory, previous HPV vaccine acceptance research, and pilot focus groups [8]. Perceived severity of HPV and susceptibility to HPV were each measured using items from Witte et al’s scales [11] (e.g. ‘I believe that HPV can be serious’; ‘It is likely that my daughter will get HPV one day’), rated on 5-point scales from strongly disagree to strongly agree (total score range from 0 to 12). Social norms relating to important others were assessed by whether respondents thought their GP, husband/partner, friends, and mother would think that they should accept vaccination for their daughter. In each case they indicated whether the target person would ‘rather I vaccinated’, ‘wouldn’t mind whether I vaccinated’ or ‘would rather I did not vaccinate’. Normative belief was assessed by asking mothers what percentage of other mothers would want the vaccination for their daughters (options from less than 10 to 100%). The attitude items are listed in Table 4. They included positive items (e.g. ‘I wish the HPV vaccination had been around when I was young’) and unfavourable items (e.g. ‘Having the HPV vaccination might make girls more likely to have sex’). Vaccine-general items included ‘I don’t want to give my daughter too many vaccinations’. All responses were on 4-point scales (strongly disagree to strongly agree). Participants were asked to indicate the age they would feel able to talk to their daughter about a number of different topics including the general purpose of vaccinations, cervical cancer, sex in general, STIs, HPV, and the HPV vaccination (from 8 or younger to 14 or older). Demographic factors included mother’s age, marital status, employment, and educational qualifications. Ethnicity and religion were recorded. In addition, participants were asked if they had experience of cancer in their close family and whether they had heard of HPV before.

L.A.V. Marlow et al. / Vaccine 25 (2007) 1945–1952

2.3. Procedure The survey was mailed to home addresses from the participating schools in February 2006, and non-responders were sent two further mailings between March and June. Where questions referred to ‘your daughter’, mothers were asked to respond for their youngest daughter between 8 and 14 years, referred to in this paper as the ‘target daughter’. As an incentive, respondents were offered entry to a draw with prizes of £500, £250, and £100. The study was approved by UCL Research Ethics Committee. 2.4. Analysis Data were analysed using SPSS Version 14.0. For some analyses, intention to accept the vaccine was dichotomised:

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mothers who indicated ‘yes probably’ or ‘yes definitely’ were classified as ‘acceptors’ and those indicating ‘probably not’, ‘definitely not’, or ‘not sure’ classified as ‘non-acceptors’. A dichotomous variable was also created for earliest age that mothers thought girls should be vaccinated against HPV (12 years or younger versus over 12). The primary analyses were univariate and used logistic regression to establish whether the predictor variables were significantly associated with both acceptance and earlier age for vaccination. Ages of mother and target daughter were treated as continuous variables; other demographic variables were treated as categorical. Social norms were treated as categorical; all other psychosocial variables were continuous. Significant predictors were entered into a multivariate logistic regression model in order to obtain an overall estimate of variance explained.

Table 2 Sample characteristics

Respondent age Target daughter age

Mean

S.D.

41.1 11.1

4.9 1.8

%

N

Employment status Employed full-time Employed part-time Self-employed Student Full time homemaker Unemployed Disabled or too ill to work

23.5 47.5 8.8 0.9 15.0 1.0 2.2

160 323 60 6 101 7 15

Marital status Single Married Cohabiting Divorced/separated Widowed

6.2 72.1 8.7 11.2 0.7

42 490 59 76 5

Education No formal qualifications GCSE/Olevel/CSE Vocational qualifications A levels/highers College qualification (below degree) Degree level education Other

5.3 28.4 8.2 9.0 16.6 23.1 8.2

36 193 56 61 113 155 56

Experience of cancer Yes No

57.2 42.8

389 291

Ethnic background White Non-white Do not wish to answer

92.6 6.3 1.2

622 42 8

Religion None Christian Other religion

24.1 73.5 2.4

162 493 16

Heard of HPV before Yes No

26.0 72.8

177 495

NB: Unaccounted percentage is missing data.

3. Results The 1255 questionnaires were distributed. Parents were asked to complete and return the questionnaire or return it blank indicating their reason for non-completion. This allowed us to exclude families who received duplicate copies of the questionnaire through two daughters (n = 44) or where no mother lived at the address (n = 6). A potential sample of 1205 received the questionnaires, of which 684 (56.8%) were returned. Response rates varied across schools (Table 1), with lower rates in more socio-economically deprived areas. Demographic characteristics are shown in Table 2. Three cases were excluded from further analysis as suspected duplicates. An additional case was excluded because the participant reported her age as 74 years and was more likely to be a grandparent. 680 cases were therefore included in the final analyses. There was very little missing data (less than 5% on any item), but where data were missing, cases were excluded from analyses involving that variable. 3.1. Vaccine acceptance and age of vaccination Seventy-five percent of mothers said they would ‘probably’ (48%) or ‘definitely’ (27%) accept the HPV vaccine for their daughter, 19% were unsure, and 6% said they probably or definitely would not. Most mothers (80%) agreed that between 10 and 14 years would be an appropriate age for vaccination. The mean age (excluding those (n = 8) who responded ‘never’) was 12.2 years (S.D. = 1.8) (see Fig. 1 for spread of responses). Overall, 59% of mothers were in favour of early vaccination (12 years or younger) and 41% favoured later vaccination. 3.2. Attitudes towards HPV and vaccination Mothers thought their daughters would be at significant risk of HPV in the future (mean susceptibility score = 8.6 (S.D. = 1.8) out of a possible 12). They also believed that

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Table 3 Mean age of discussing HPV related topics

The purpose of vaccinations Sex in general Cervical cancer HPV vaccination HPV Sexually transmitted infections generally

Mean

S.D.

Statistical difference from discussing HPV vaccination

9.58 10.61 11.04 11.08 11.18 11.38

1.72 1.73 1.69 1.61 1.60 1.57

t = −24.46, p < 0.0001 t = −8.07, p < 0.0001 n.s.

Fig. 1. Percentage of mothers endorsing each age for HPV vaccination.

HPV could be severe (mean severity score = 9.5 (S.D. = 1.9) out of 12). In terms of social norms, nearly all mothers thought other people around them would either rather they vaccinated or would not mind. This was the case for their GP (99.2%), husband/partner (94.5%), friends (96.5%), mother (92.7%), and other people close to them (95.3%). The modal answer to the normative belief question (what percentage of other mothers would want HPV vaccination for their daughters) was 80%. Most mothers (77%) wished the vaccine had been around when they themselves were young, and 70% would be glad if the vaccination meant an end to smear tests. The majority agreed they would be glad if the vaccination also prevented genital warts (92%). Few thought that HPV vaccination would make girls more likely to have sex (12%), but slightly more saw an increased risk of unprotected sex (18%). Potential vaccine side effects were a worry for 65% of mothers, and 43% were concerned about giving their daughter too many vaccinations. The age at which mothers would discuss related topics with their daughter varied by topic (see Table 3). Mothers thought their daughter would need to be older to discuss HPV vaccination than the general purpose of vaccinations or sex in general, and even older to discuss HPV or STIs. 3.3. Demographic, cultural, and psychosocial predictors of acceptance Most demographic variables, including parental age, parental education and ethnicity, were not associated with

t = 4.00, p < 0.0001 t = 7.27, p < 0.0001

acceptance. Being of an ‘other religion’ was associated with lower acceptance than being of no religion (OR = 0.32). Having an older ‘target daughter’ (OR = 1.15) or a family member with cancer were associated with higher acceptance (OR = 1.61). Results are shown in Table 4. Higher scores on perceived severity of HPV (OR = 1.15) or susceptibility (OR = 1.27) were associated with higher acceptance. Mothers who believed their husband/partner (OR = 14.51), mother (OR = 6.28), and friends (OR = 9.13) would be in favour of the vaccine, or expected a greater percentage of other mothers to want the vaccine for their daughters (OR = 1.79) were more likely to say they would accept vaccination. Mothers who were willing to discuss cervical cancer (OR = 1.17), sex (OR = 1.12), STIs (OR = 1.22), HPV (OR = 1.26) or the HPV vaccine (OR = 1.29) at earlier ages were more likely to accept the vaccine. As expected, mothers who agreed with positive statements about HPV were more likely to be acceptors, while those agreeing with the negative statements about HPV were less likely to accept the vaccine. General concerns about vaccination were associated with not intending to accept the vaccine (see Table 4 for odds ratios associated with each of the attitude statements). The multivariate analysis was included to assess the amount of variance explained by the demographic, cultural, and psychological variables together. The model was significant (χ2 (17) = 245.63, p < 0.0001) and a good fit for the data (Hosmer & Lemeshow test; χ2 (8) = 4.71, p = 0.79); explaining a reasonable proportion of the variance (pseudo R2 = 0.34–0.52). Six variables were significant predictors of vaccine acceptance in the multivariate model: discussing sex at an early age (OR = 1.22, CI: 1.05–1.43), high normative belief (OR = 1.53, CI: 1.30–1.79), husband’s approval of the vaccination (OR = 8.18, CI: 2.21–30.25), and mothers wishing the vaccine had been around when they were young (OR = 2.99, CI: 1.87–4.78). Mothers who were concerned about giving too many vaccines (OR = 0.43, CI: 0.28–0.68) or about vaccine side effects (OR = 0.48, CI: 0.31–0.73) were less likely to accept the vaccine. 3.4. Demographic, cultural, and psychosocial predictors of earlier acceptance age White mothers were more in favour of earlier vaccination than non-white mothers (OR = 3.09), while older mothers (OR = 0.93) and those who were Christian (OR = 0.53) or

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Table 4 Demographic, cultural, and psychosocial predictors of attitudes towards HPV vaccination Intention to vaccinate OR [95% CI] Demographic/cultural predictors Respondent age

Earlier age for vaccination P-value

OR [95% CI]

P-value

0.98 [0.94–1.01]

0.177

0.93 [0.90–0.97]

< 0.0001

Employment status Employed (full-time/part-time/self-employed) Unemployed Full-time homemaker

1.00 0.83 [0.16–4.35] 0.96 [0.59–1.56]

0.829 0.875

1.00 0.50 [0.11–2.25] 0.71 [0.56–1.10]

0.365 0.123

Marital status Married Single Cohabiting Divorced/separated

1.00 0.70 [0.36–1.38] 1.22 [0.68–2.17] 1.87 [0.89–3.92]

0.302 0.503 0.097

1.00 0.51 [0.26–0.97] 1.07 [0.66–1.79] 1.11 [0.62–1.97]

0.041 0.747 0.726

Education level None/GCSE/O’level A-level or equivalent University degree

1.00 1.25 [0.80–1.98] 0.81 [0.52–1.26]

0.330 0.351

1.00 0.96 [0.65–1.42] 1.00 [0.67–1.50]

0.844 0.994

Ethnicity Non-white White Do not wish to answer

1.00 1.77 [0.92–3.41] 0.33 [0.07–1.59]

0.089 0.169

1.00 3.09 [1.59–5.98] 3.33 [0.69–16.00]

0.001 0.132

Religion None Christian Other

1.00 0.72 [0.46–1.12] 0.32 [0.11–0.93]

0.138 0.036

1.00 0.53 [0.36–0.78] 0.14 [0.04–0.45]

0.001 0.001

Experience of cancer in family Age of target child Previous knowledge of HPV

1.61 [1.14–2.29] 1.15 [1.04–.27] 1.25 [0.83–1.88]

0.007 0.007 0.287

1.24 [0.90–1.69] 0.93 [0.85–1.02] 1.27 [0.89–1.27]

0.186 0.112 0.189

1.15 [1.05–1.26] 1.27 [1.14–1.40]

0.003 <0.0001

1.06 [0.98–1.16] 1.26 [1.15–1.40]

0.165 <0.0001

1.00 14.51 [6.15–34.25] 11.56 [3.76–35.51]

<0.0001 <0.0001

1.00 1.82 [0.83-4.00] 1.10 [0.40-3.05]

0.138 0.852

1.78 [1.59–2.01] 1.12 [1.01–1.24]

<0.0001 0.036

1.15 [1.05-1.26] 1.37 [1.24–1.51]

0.002 <0.0001

HPV specific positive items I wish the vac had been around when I was young I would be glad if the vac meant an end to smears I would be glad if the vaccine was against genital warts

5.21 [3.75–7.24] 1.89 [1.52–2.35] 2.78 [2.01–3.86]

<0.0001 <0.0001 <0.0001

2.03 [1.59–2.61]

<0.0001

1.19 [0.91–1.56]

0.206

HPV specific negative items Vac would make girls more likely to have sex Vac would make girls more likely to have unprotected sex

0.47 [0.36–0.62] 0.54 [0.41–0.71]

<0.0001 <0.0001

0.61 [0.47–0.78] 0.66 [0.52–0.85]

<0.0001 0.001

General vaccination concerns I would be very worried about side effects I do not want to give my daughter too many vacs

0.37 [0.28–0.50] 0.22 [0.15–0.31]

<0.0001 <0.0001

0.65 [0.51–0.82] 0.53 [0.41–0.69]

<0.0001 <0.0001

Psychosocial predictors Severity Susceptibility Social norm—husband Would not want me to vaccinate Would want me to vaccinate/would not mind N/A Normative belief Discussing sex at an early age

from other religious groups (OR = 0.14) were less in favour of earlier vaccination. Other demographic/cultural variables including parental education and age of target child, or having cancer in the family, were not associated with vaccine acceptance age. Perceiving their daughter as more susceptible to HPV was associated with earlier vaccination (OR = 1.26), as was

believing that other mothers would want the vaccine for their daughter (OR = 1.15). Perceived severity of HPV and social norms were not associated with age of vaccination. Mothers who were willing to discuss related topics with their daughter at an earlier age, were also more likely to be in favour of early age vaccination; this was the case for discussing cervical cancer (OR = 1.58), sex (OR = 1.37), STIs (OR = 1.62),

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HPV (OR = 7.78), or the HPV vaccine (OR = 1.87). Only one of the HPV-specific positive items was associated with endorsing earlier vaccination (mothers who wished the vaccine had been around then they were young were more likely to endorse earlier vaccination; OR = 2.03). However all the negative items were associated with being less likely to accept earlier vaccination. The multivariate model was significant (χ2 (17) = 126.54, p < 0.0001) and a good fit for the data (Hosmer & Lemeshow test; χ2 (8) = 11.49, p = 0.18) and explained a significant proportion of the variance in age of acceptance (pseudo R2 = 0.19–0.26). Seven variables emerged as significant predictors of early vaccine acceptance in the multivariate model: mother’s age (OR = 0.92, CI: 0.89–0.96), discussing sex at an early age (OR = 1.35, CI: 1.21–1.52), believing their daughter would one day be susceptible to HPV (OR = 1.13, CI: 1.01–1.27), and wishing the vaccine had been around when they were young (OR = 1.69, CI: 1.23–2.34). Mothers who were unmarried (OR = 0.39, CI: 0.18–0.85), Christian (OR = 0.62, CI: 0.39–0.98) or concerned about giving too many vaccines (OR = 0.65, CI: 0.47–0.90) were less likely to accept early vaccination. Ethnicity was no longer significant once the psychological variables were included in the model, probably because they mediated the ethnicity effect.

4. Discussion Rates of HPV vaccine acceptance were similar to those reported from the United States [12,13] with 75% of mothers saying they would ‘probably’ or ‘definitely’ accept the HPV vaccination for their daughter. While few mothers said they would not accept the vaccine (only 6%), a significant proportion (19%) were unsure about it. Campaigns to ensure good uptake of the HPV vaccination may benefit from focusing on this undecided group. HPV vaccination is recommended for 11–12-year-old girls in the US, with licensing covering girls as young as 9. In the present study, a substantial minority (over 40%) were unwilling to endorse ages 12 or younger as appropriate for HPV vaccination. Educational materials aimed at parents will need to include a good justification for why the vaccine is recommended at a particular age. Respondents who were religious were less likely to accept the vaccine and more likely to be in favour of later vaccination; consistent with previous findings [9]. However, parental educational level was not associated with intention to vaccinate or endorsing earlier vaccination, although the trend was for higher acceptance among mothers with less education. One previous study had found lower income to be associated with HPV vaccine acceptance [14], but others have found no association with markers of SES [9,12]. Some of the psychosocial variables identified as predictors in this study are consistent with previous research. Normative beliefs of peer groups have been implicated in previous work [15], which the present results confirmed. This suggests

that emphasising the socially normative nature of vaccinating against HPV is likely to facilitate public acceptance. Mothers who thought their husband/partner and GP would be in favour were more likely to accept for their daughter, highlighting the importance of fathers and primary care staff in the decision process. This is the first quantitative study to investigate the correlates of accepting early vaccination; a topic that has provoked controversy in the media. Consistent with findings from qualitative work, the need to discuss the vaccine with preadolescents emerged as a barrier to vaccination [8]. Mothers appeared to be prepared to discuss vaccination at around the same time that they would discuss cervical cancer, but would not discuss HPV or STIs until their daughters were older. This suggests that some mothers would prefer to explain the vaccination as a vaccine ‘against cancer’ or simply as ‘one of the vaccines you have’, and avoid details about HPV infection until the child is older. Materials advising parents about how to talk to their child about the vaccine may help to ensure this does not remain a barrier. Mothers who intended to accept HPV vaccination or were in favour of early vaccination had more positive attitudes towards the vaccine across the board. Negative attitudes towards HPV vaccination (e.g. it may cause promiscuity) and concerns about safety (e.g. vaccine side effects, too many vaccinations) were stronger in those who would not accept the vaccine or favoured later vaccination. Concern about the safety of vaccines is a common explanation for why parents fail to vaccinate their children [16,17], and there appears to be a belief among some parents that too many vaccinations are bad and can lead to ‘weakening of the immune system’ [18]. Addressing such misconceptions is likely to be beneficial in increasing uptake. 4.1. Limitations This study used a school-based survey methodology, with larger schools being chosen from the selected areas, so participants may not be representative of the UK population. In this sample, religion and ethnicity were associated with being in favour of later vaccination, but as the sample was relatively homogeneous in ethnicity and religion, more research is needed to investigate cultural differences in attitudes to vaccination. All mothers were provided with a page of information about HPV and the vaccine. Although the material was fairly standard (see Appendix A), the specific content could have influenced the responses and results may be different with alternative information. 4.2. Conclusion These results present an encouraging view of parental acceptance both of vaccination and vaccination before age 12, suggesting that a school-based immunisation programme is likely to meet with a favourable response. There was no evidence that lower SES parents were less enthusiastic about

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the vaccine. Barriers to HPV vaccination came from both general concerns about vaccinations (e.g. too many vaccines, side effects) and specific concerns related to children’s sexual behaviour. Future promotion of vaccination might consider emphasising the socially normative nature of vaccination and informing parents of the immunological as well as the behavioural arguments for early vaccination age.

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• If HPV infection persists, it can cause cell changes which eventually lead to cervical cancer if left untreated. • HPV can also cause genital warts, but the types that cause warts do not cause cervical cancer. Can HPV be detected and treated?

Acknowledgements The study was funded by Sanofi Pasteur MSD. Jane Wardle and Laura Marlow are supported by Cancer Research UK. Jo Waller has an ESRC/MRC fellowship. We thank the schools involved for their help and the parents who took the time to complete the questionnaires. Contributors: All authors contributed to the overall conception and design of the study. Laura Marlow and Jane Wardle were responsible for data analysis and all authors contributed to interpretation of the results. The article was drafted by Laura Marlow and revised critically by Jane Wardle and Jo Waller. All authors approved the final version to be published. Jane Wardle is the guarantor.

Appendix A

• Cervical screening (the smear test) picks up cell changes in the cervix that are caused by HPV. • Treating cells that have been affected by HPV prevents cancer from developing. What is the HPV vaccination? • A vaccination has now been developed that will protect women against HPV. • The vaccination will help to prevent cervical cancer. • It will also protect against genital warts. • Trials of the vaccination have shown it to be 100% effective in protecting against HPV. • To give full protection, the vaccination must be given to girls before they become sexually active.

Information provided about HPV References What causes cervical cancer? • Scientists have linked nearly all cases of cervical cancer to a common virus called human papillomavirus or HPV. What is HPV? • HPV is a group of viruses—there are many different types. • HPV is sexually transmitted, caught by having sexual contact with someone who is infected. • HPV is very common–most sexually active people will get it at some point in their lives. • Condoms do not provide full protection against HPV, although they may reduce the risk of infection. How serious is HPV? • The types of HPV that cause cervical cancer have no symptoms. • HPV can lie dormant for many years without causing any problems. • HPV usually clears up on its own without needing any treatment.

[1] Bosch FX, Munoz N. The viral etiology of cervical cancer. Virus Res 2002;89(2):183–90. [2] Villa LL, Costa RL, Petta CA, Andrade RP, Ault KA, Giuliano AR, et al. Prophylactic quadrivalent human papillomavirus (types 6, 11, 16 and 18) L1 virus-like particle vaccine in young women: a randomised double-blind placebo-controlled multicentre phase II efficacy trial. Lancet Oncol 2005;6(5):271–8. [3] Harper DM, Franco EL, Wheeler C, Ferris DG, Jenkins D, Schuind A, et al. Efficacy of a bivalent L1 virus-like particle vaccine in prevention of infection with human papillomavirus types 16 and 18 in young women: a randomised controlled trial. Lancet 2004;364(9447):1757– 65. [4] Merck. European Commission approves Gardasil® , Merck’s cervical cancer vaccine. Retrieved September 29, 2006. http://www.merck.com/newsroom/press releases/product /2006 0922a.html. [5] Kuehn BM. CDC panel backs routine HPV vaccination. JAMA 2006;296(6):640–1. [6] Goldie SJ, Kohli M, Grima D, Weinstein MC, Wright TC, Bosch FX, et al. Projected clinical benefits and cost-effectiveness of a human papillomavirus 16/18 vaccine. J Natl Cancer Inst 2004;96(8):604– 15. [7] Zimet GD. Improving adolescent health: focus on HPV vaccine acceptance. J Adolesc Health 2005;37(6):S17–23. [8] Waller J, Marlow LA, Wardle J. Mothers’ attitudes towards preventing cervical cancer through human papillomavirus vaccination: a qualitative study. Cancer Epidemiol Biomarkers Prev 2006;15(7):1257–61. [9] Brabin L, Roberts SA, Farzaneh F, Kitchener HC. Future acceptance of adolescent human papillomavirus vaccination: a survey of parental attitudes. Vaccine 2006;24(16):3087–94.

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