Dataset Information

Effectiveness of various human papillomavirus vaccination strategies: A community randomized trial in Finland.

ABSTRACT:

Introduction

We conducted a community-randomized trial (NCTBLINDED) in Finland to assess gender-neutral and girls-only vaccination strategies with the AS04-adjuvanted human papillomavirus (HPV)-16/18 (AS04-HPV-16/18)vaccine.

Methods

Girls and boys (12-15 years) were invited. We randomized 33 communities (1:1:1 ratio): Arm A: 90% of randomly selected girls and boys received AS04-HPV-16/18 vaccine and 10% received hepatitis B vaccine (HBV); Arm B: 90% of randomly selected girls received AS04-HPV-16/18 vaccine, 10% of girls received HBV, and all boys received HBV; Arm C: all participants received HBV. Effectiveness measurements against prevalence of HPV-16/18 cervical infection were estimated in girls at 18.5 years. The main measures were: (1) overall effectiveness comparing Arms A or B, regardless of vaccination status, vs Arm C; (2) total effectiveness comparing AS04-HPV-16/18 vaccinated girls in pooled Arms A/B vs Arm C; (3) indirect effectiveness (herd effect) comparing girls receiving HBV or unvaccinated in Arm A vs Arm C. Co-primary objectives were overall effectiveness following gender-neutral or girls-only vaccination.

Results

Of 80,272 adolescents invited, 34,412 were enrolled. Overall effectiveness was 23.8% (95% confidence interval: -19.0, 51.1; P = 0.232) with gender-neutral vaccination. Following girls-only vaccination, overall effectiveness was 49.6% (20.1, 68.2; P = 0.004). Total effectiveness was over 90% regardless of vaccination strategy. No herd effect was found. Immunogenicity of the AS04-HPV-16/18 vaccine was high in both sexes.

Conclusions

This study illustrates the difficulty in conducting community randomized trials. It is not plausible that vaccinating boys would reduce overall effectiveness, and the apparent lack of herd effect was unexpected given findings from other studies. This analysis was likely confounded by several factors but confirms the vaccine's high total effectiveness as in clinical trials.

SUBMITTER: Lehtinen M

PROVIDER: S-EPMC8559511 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundCervical cancer elimination through human papillomavirus (HPV) vaccination programs requires the attainment of herd effect. Due to its uniquely high basic reproduction number, the vaccination coverage required to achieve herd effect against HPV type 16 exceeds what is attainable in most populations. We have compared how gender-neutral and girls-only vaccination strategies create herd effect against HPV16 under moderate vaccination coverage achieved in a population-based, community-randomized trial.Methods and findingsIn 2007-2010, the 1992-1995 birth cohorts of 33 Finnish communities were randomized to receive gender-neutral HPV vaccination (Arm A), girls-only HPV vaccination (Arm B), or no HPV vaccination (Arm C) (11 communities per trial arm). HPV16/18/31/33/35/45 seroprevalence differences between the pre-vaccination era (2005-2010) and post-vaccination era (2011-2016) were compared between all 8,022 unvaccinated women <23 years old and resident in the 33 communities during 2005-2016 (2,657, 2,691, and 2,674 in Arms A, B, and C, respectively). Post- versus pre-vaccination-era HPV seroprevalence ratios (PRs) were compared by arm. Possible outcome misclassification was quantified via probabilistic bias analysis. An HPV16 and HPV18 seroprevalence reduction was observed post-vaccination in the gender-neutral vaccination arm in the entire study population (PR16 = 0.64, 95% CI 0.10-0.85; PR18 = 0.72, 95% CI 0.22-0.96) and for HPV16 also in the herpes simplex virus type 2 seropositive core group (PR16 = 0.64, 95% CI 0.50-0.81). Observed reductions in HPV31/33/35/45 seroprevalence (PR31/33/35/45 = 0.88, 95% CI 0.81-0.97) were replicated in Arm C (PR31/33/35/45 = 0.79, 95% CI 0.69-0.90).ConclusionsIn this study we only observed herd effect against HPV16/18 after gender-neutral vaccination with moderate vaccination coverage. With only moderate vaccination coverage, a gender-neutral vaccination strategy can facilitate the control of even HPV16. Our findings may have limited transportability to other vaccination coverage levels.Trial registrationClinicalTrials.gov number NCT00534638, https://clinicaltrials.gov/ct2/show/NCT00534638.

Project description:ImportanceDespite availability of a safe and effective vaccine, an estimated 36 500 new cancers in the US result from human papillomavirus (HPV) annually. HPV vaccine uptake falls short of national public health goals and lags other adolescent vaccines.ObjectiveTo evaluate the individual and combined impact of 2 evidence-based interventions on HPV vaccination rates among 11- and 12-year-old children.Design, setting, and participantsThe study team conducted a cluster randomized clinical trial with a stepped-wedge factorial design at 6 primary care practices affiliated with Mayo Clinic in southeastern Minnesota. Using block randomization to ensure balance of patient volumes across interventions, each practice was allocated to a sequence of four 12-month steps with the initial baseline step followed by 2 intermediate steps (none, 1, or both interventions) and a final step wherein all practices implemented both interventions. Each month, all eligible children who turned 11 or 12 years in the 2 months prior were identified and followed until the end of the step. Data were analyzed from April 2018 through March 2019. Participants included children who turned 11 or 12 years old and were due for a dose of the HPV vaccine.InterventionsParents of eligible patients were mailed reminder/recalls following their child's birthdays. Health care professionals received confidential audit/feedback on their personal in-office success with HPV vaccine uptake via intra-campus mail. These 2 interventions were assessed separately and in combination.Main outcomes and measuresEligible patients' receipt of any valid dose of HPV vaccine during the study step.ResultsThe cohort was comprised of 9242 11-year-olds (5165 [55.9%]) and 12-year-olds (4077 [44.1%]), and slightly more males (4848 [52.5%]). Parent reminder/recall resulted in 34.6% receiving a dose of HPV vaccine, health care professional audit/feedback, 30.4%, both interventions together resulted in 39.7%-all contrasted to usual care, 21.9%. Compared with usual care, the odds of HPV vaccination were higher for parent reminder/recall (odds ratio [OR], 1.56; 95% CI, 1.23-1.97) and for the combination of parent reminder/recall and health care professional audit/feedback (OR, 2.03; 95% CI, 1.44-2.85). Health care professional audit/feedback alone did not differ significantly from usual care (OR, 1.19; 95% CI, 0.94-1.51).Conclusions and relevanceIn this cluster randomized trial, the combination of parent reminder/recall and health care professional audit/feedback increased the odds of HPV vaccination compared with usual care. These findings underscore the value of simultaneous implementation of evidence-based strategies to improve HPV vaccination.

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