Transmission Reduction and Prevention With HPV Vaccination (TRAP-HPV) Study

Human papillomavirus (HPV) vaccination for the prevention of cervical cancer and other HPV-related diseases: a network meta-analysis

Cervical cancer is the fourth most common cause of cancer-related death amongst females worldwide. Persistent infection with high-risk human papillomavirus (HPV) is the key factor in cervical cancer development. HPV vaccines aim to prevent cancer by generating antibodies against HPV infection. To evaluate the safety and efficacy of HPV vaccines, in females and males, to prevent cervical cancer and other HPV-related diseases, in standard (pairwise) and network meta-analysis (NMA) of randomised controlled trials. On 10 January 2022, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase. We searched Epistemonikos, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, the Health Technology Assessment database and vaccine manufacturer websites, and we checked reference lists from other relevant systematic reviews. We applied for Clinical Study Reports (CSRs) from the European Medicines Agency. An update search of electronic databases was done on 18 September 2024. We included randomised controlled trials (RCTs) regardless of language or publication status, assessing HPV vaccines pre-qualified by the World Health Organization (WHO) (Cervarix, Gardasil, Gardasil-9 and Cecolin). We used methods recommended by Cochrane. We primarily used CSRs to collect data, and we included outcome data irrespective of participants' baseline HPV infection or serostatus. We assessed risk of bias using the Cochrane tool (RoB 2). All outcomes were dichotomous, and we estimated risk ratios (RR) with 95% confidence intervals (CI). We used pairwise analysis for all outcomes. Where data were available, we carried out NMA for critical outcomes for networks in females and males in three age groups, ranking the vaccines using surface under the cumulative ranking curve (SUCRA) and mean ranks. We assessed the certainty of evidence using the GRADE approach. We included 60 individual studies with 157,414 participants ranging in follow-up from seven months to 11 years. Few participants were under 15. There were no studies for males under 15 years and males over 25 years. We obtained CSRs for 33 of the included studies. We assessed the risk of bias as low to 'some concerns' for the critical outcomes. Cancer and pre-cancer outcomes The studies were not of sufficient duration for cancers to develop. Four studies reported on cancer. No cancers were detected. Critical pre-cancer outcomes were reported in 15- to 25-year-old populations by 11 studies and in > 25-year-old females by three studies with up to seven years follow-up. None were reported in the under 15 years age group. In 15- to 25-year-old females, there was a reduction in CIN2+ irrespective of HPV type after six years (RR 0.70, 95% CI 0.56 to 0.88) (moderate-certainty) and a larger reduction in CIN2+ from vaccine-matched HPV types after six years (RR 0.40, 95% CI 0.30 to 0.54) (moderate-certainty). In females over 25 years old, there was little to no difference between Cervarix and Gardasil compared with control (moderate-certainty). There was no evidence on CIN2+ irrespective of HPV type from studies assessing Cecolin, or from studies assessing different dose schedules. In 15- to 25-year-old females, there was a slight reduction in vaccine-matched HPV-type high-grade vulval (VIN) or vaginal (VaIN) intraepithelial neoplasia following vaccination with Gardasil or Gardasil-9 (moderate-certainty). The NMA found a slight reduction of 1 case per 1000 following Gardasil (RR 0.21, 95% CI 0.1 to 0.45) and 0 cases per 1000 following Gardasil-9 (RR 0.16, 95% CI 0.05 to 0.51). Little to no difference was found in the NMA for Cervarix compared with control (RR 0.28, 95% CI 0.06 to 1.37), or for Cervarix, Gardasil and Gardasil-9 compared to each other. There was a reduction in high-grade anal intraepithelial neoplasia (AIN) irrespective of HPV type in the Gardasil group in one study in men who have sex with men (RR 0.75, 95% CI 0.53 to 1.07) (low-certainty). For both high-grade penile intraepithelial neoplasia (PeIN) irrespective of HPV type and vaccine-matched HPV-type high-grade PeIN, little to no difference per 1000 participants was reported in the Gardasil group in one study with 3880 participants at 36 months follow-up (RR 1.00, 95% CI 0.20 to 4.93) (low-certainty). Serious adverse events In a pairwise analysis of serious adverse events in 39 studies across all vaccine types with 97,272 participants, there was little to no difference in the HPV vaccine groups compared with the control group at up to 72 months follow-up (RR 0.99, 95% CI 0.94 to 1.04) (high-certainty). Treatment rates for HPV-related pre-invasive disease In pairwise analysis of five studies with 38,606 participants, there were 12 fewer people that needed to seek treatment per 1000 participants (95% CI 5 to 17 fewer per 1000) in the HPV vaccine groups compared with the control group rate at up to 84 months follow-up (RR 0.76, 95% CI 0.65 to 0.89) (moderate-certainty). Anogenital warts In pairwise analysis of three studies with 21,271 participants, there were 25 fewer cases of anogenital warts irrespective of HPV type per 1000 participants (95% CI 22 to 28 fewer per 1000) in the HPV vaccine groups compared with the control group rate at up to 48 months follow-up (RR 0.38, 95% CI 0.32 to 0.46) (high-certainty). In the NMA for females 15 to 25 years old, Gardasil-9 was most likely to reduce the risk of developing anogenital warts. The evidence in this network meta-analysis of HPV vaccines is based on extensive searches and analyses. There is evidence from randomised controlled trials that HPV vaccination reduces the risk of pre-cancerous outcomes such as CIN2+ and anogenital warts. No data were available for cervical cancer or other cancer outcomes, and no data on pre-cancer outcomes were available for vaccination under age 15 years. There were no safety concerns noted in the studies.

Transmission reduction and prevention with HPV vaccination (TRAP-HPV) study protocol: a randomised controlled trial of the efficacy of HPV vaccination in preventing transmission of HPV infection in heterosexual couples

Introduction Human papillomavirus (HPV) is a causal agent of malignancies including cervical, vulvar, vaginal, penile, anal and oropharyngeal cancer, as well as benign conditions such as anogenital warts. HPV vaccination protects individuals against infections with the target HPV types and their clinical outcomes. However, little is known about the protection an immunised individual confers to their sexual partner or its impact on HPV transmission dynamics. In this context, the Transmission Reduction and Prevention with HPV vaccination (TRAP-HPV) study was designed to determine the efficacy of an HPV vaccine in reducing transmission of genital and oral HPV infection in sexual partners of vaccinated individuals. Methods and analysis The TRAP-HPV study is an ongoing randomised controlled trial among heterosexual couples living in Montreal, Canada. Sexually active couples, aged between 18 and 45 years, who have been in a relationship no longer than 6 months are considered eligible. Participants are independently randomised to receive either the intervention HPV vaccine, Gardasil 9, or a placebo hepatitis A vaccine, Avaxim, creating four vaccination groups among couples: intervention–intervention, intervention–placebo, placebo–intervention and the placebo–placebo. Participants provide genital (vaginal/penile) and oral samples at baseline and five follow-up visits over a 1-year duration. Linear Array HPV genotyping is used to detect 36 HPV types. Cox proportional hazard regression models will be used to estimate the effect of vaccination on HPV transmission. Ethics and dissemination The TRAP-HPV study received ethical approval by institutional review boards McGill University, Concordia University and Centre Hospitalier de l’Université de Montréal. Before enrolment, all participants provide informed written consent. Results will be published in peer-reviewed journals and presented at national and international conferences. The generated empirical evidence could be used in mathematical models of vaccination to inform policymakers in Canada and elsewhere. Trial registration number NCT01824537 .

Eduardo L. Franco

Professor Eduardo Franco is a Distinguished James McGill Professor in the Departments of Oncology and Epidemiology & Biostatistics at McGill University. He served as Director of the Division of Cancer Epidemiology (1995–2024) and Chair of the Department of Oncology (2011–23). Earlier, he was on the faculty of Université du Québec and Head of the Epidemiology Unit at the Ludwig Institute for Cancer Research in São Paulo, Brazil. He holds biology degrees from the Universidade de Campinas and MPH and DrPH degrees from the University of North Carolina at Chapel Hill. His early training included fellowships at the U.S. Centers for Disease Control, the International Agency for Research on Cancer, the U.S. National Cancer Institute, and Louisiana State University. Since 1985, his research has contributed to understanding and preventing cervical cancer and HPV‑related diseases, and to studies of upper aerodigestive tract, prostate, endometrial, and childhood cancers. His work spans cancer screening evaluation, measurement error, and factors influencing cancer survival. He has led international collaborations in the Americas, Europe, Africa, and through IARC. His research has been funded by CIHR, NIH, the National Cancer Institute of Canada, the Canadian Cancer Society, FRSQ, and the Cancer Research Society. As of March 2026, he had published more than 600 scientific papers (Google Scholar link: https://scholar.google.com/citations?user=9GDejd4AAAAJ&hl=en). His work has appeared in The Lancet, JAMA, NEJM, JNCI, BMJ, and PLOS Medicine. He is Editor‑in‑Chief of the Journal of the National Cancer Institute and JNCI Monographs, and Editor‑in‑Chief Emeritus of Preventive Medicine and Preventive Medicine Reports. He has served on more than a dozen major editorial boards, on scientific and grant‑review panels internationally, and twice advised the U.S. President’s Cancer Panel. Professor Franco has mentored 101 graduate students, 36 postdoctoral fellows, and 41 undergraduate trainees, and has taught widely in North America, Latin America, Europe, Asia, and the Middle East. He has held leadership roles in 68 conference committees, chaired the 16th World Congress of Epidemiology, and served as Vice-President and President of the Canadian Society for Epidemiology and Biostatistics. He is President‑Elect of the International Epidemiological Association (2024–27). His honours include major lifetime achievement awards from McGill and international organizations, and national distinctions such as Officer of the Order of Canada, Fellow of the Royal Society of Canada, the Canadian Academy of Health Sciences, and Foreign Fellow of the Brazilian Academy of Sciences.

Hanna Bergman