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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., This community randomized trial evaluating two HPV vaccination strategies (girls only and gender neutral) in Finland failed to show indirect benefit for girls by vaccinating boys. Several factors might have prevented to show herd effect such as randomization bias. However, the study confirms the high total effectiveness of the vaccine in girls.

With optimal strategy, human papillomavirus (HPV) vaccines have the potential to control HPV. We have assessed vaccine efficacy (VE), herd effect (HE) of HPV vaccination and overall protective effectiveness (PE) against high-risk HPV infections by HPV type and vaccination strategy in a community-randomized trial using the bivalent HPV16/18 vaccine. We randomized 33 communities to gender-neutral HPV vaccination (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Entire 1992-1995 male (40,852) and female (39,420) birth cohorts were invited, and 11,662 males and 20,513 females vaccinated with 20-30% and 45% coverage in 2007-2010. During 2010-2014, 11,396 cervicovaginal samples were collected from 13,545 18.5-year-old attendees. HPV typing was performed by a high-throughput PCR. VE was calculated for HPV vaccinated women and HE for non-HPV-vaccinated women, using the HBV vaccinated, for HE all non-HPV vaccinated, Arm C women as controls. PE was calculated as coverage rate-weighted mean of VE + HE. HPV16/18/45 and 31/33/35 VEs varied between 86-94% and 30-66%, respectively. Only the gender-neutral vaccination provided significant HEs against HPV18 (61%) and HPV31 (72%) in the 1995 birth cohort-increased HEs against HPV33 (39%) and HPV35 (42%) were also observed. Due to the increased HEs, PEs for HPV16/18/45 and HPV31/33/35 were comparable in the gender-neutral arm 1995 birth cohort. High vaccine efficacy against HPV16/18/45 and, gender-neutral vaccination-enforced, herd effect against HPV18/31/33/35 by the bivalent vaccine rapidly provides comparable overall protective effectiveness against six oncogenic HPV types: 16/18/31/33/35/45.

Efficacy of human papillomavirus (HPV) vaccines promises to control HPV infections. However, HPV vaccination programs may lay bare an ecological niche for non-vaccine HPV types. We evaluated type-replacement by HPV type and vaccination strategy in a community-randomized trial executed in HPV vaccination naive population. Thirty-three communities were randomized to gender-neutral vaccination with AS04-adjuvanted HPV16/18 vaccine (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Resident 1992-95 born boys (40,852) and girls (39,420) were invited. 11,662 boys and 20,513 girls were vaccinated with 20–30% and 45–48% coverage, respectively. HPV typing of 11,396 cervicovaginal samples was performed by high throughput PCR. Prevalence ratios (PR) between arms and ranked order of HPV types and odds ratio (OR) for having multiple HPV types in HPV16 or 18/45 positive individuals were calculated. The ranked order of HPV types did not significantly differ between arms or birth cohorts. For the non-HPV vaccinated 1992–1993 birth cohorts increased PR, between the gender-neutral intervention versus control arms for HPV39 (PRA 1.84, 95% CI 1.12–3.02) and HPV51 (PRA 1.56, 95% CI 1.11–2.19) were observed. In the gender-neutral arm, increased clustering between HPV39 and the vaccine-covered HPV types 16 or 18/45 (ORA16 = 5.1, ORA18/45 = 11.4) was observed in the non-HPV vaccinated 1994–1995 birth cohorts. Comparable clustering was seen between HPV51 and HPV16 or HPV18/45 (ORB16 = 4.7, ORB18/45 = 4.3), in the girls-only arm. In conclusion, definitively consistent postvaccination patterns of HPV type-replacement were not observed. Future occurrence of HPV39 and HPV51 warrant investigation.

Human papillomavirus (HPV) vaccine is efficacious but the real-life effectiveness of gender-neutral and girls-only vaccination strategies is unknown. We report a community-randomized trial on the protective effectiveness [(PE) = vaccine efficacy (VE) + herd effect (HE)] of the two strategies among females in virtually HPV vaccination naive population. We randomized 33 Finnish communities into Arm A) gender-neutral vaccination with AS04-adjuvanted HPV16/18 vaccine (11 communities), Arm B) HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (11 communities) or Arm C) gender-neutral HBV vaccination (11 communities). All resident 39,420 females and 40,852 males born 1992-95 were invited in 2007-09. Virtually all (99%) 12- to 15-year-old participating males (11,662) and females (20,513) received three doses resulting in uniform 20-30% male and 50% female vaccination coverage by birth cohort. Four years later (2010-14) 11,396 cervicovaginal samples obtained from 18.5 year-old women were tested for HPV DNA, and prevalence of cervical HPV infections by trial arm and birth cohort was the main outcome measure. VEs against HPV16/18 varied between 89.2% and 95.2% across birth cohorts in arms A and B. The VEs against non-vaccine types consistent with cross-protection were highest in those born 1994-95 for HPV45 (VEA 82.8%; VEB 86.1%) and for HPV31 (VEA 77.6%, VEB 84.6%). The HEs in the non HPV-vaccinated were statistically significant in those born 1994-95 for HPV18 (HEA 51.0%; 95% CI 8.3-73.8, HEB 47.2%; 6.5-70.2) and for HPV31/33 in arm A (HEA 53.7%; 22.1-72.5). For HPV16 and 45 no significant herd effects were detected. PE estimates against HPV16/18 were similar by both strategies (PEA 58.1%; 45.1-69.4; PEB 55.7%; 42.9-66.6). PE estimates against HPV31/33 were higher by the gender-neutral vaccination (PEA 60.5%; 43.6-73.4; PEB 44.5%; 24.9-60.6). In conclusion, while gender-neutral strategy enhanced the effectiveness of HPV vaccination for cross-protected HPV types with low to moderate coverage, high coverage in males appears to be key to providing a substantial public health benefit also to unvaccinated females. Trial registration www.clinicaltrials.gov.com NCT000534638.

Oncogenic non-vaccine human papillomavirus (HPV) types may conceivably fill the vacated ecological niche of the vaccine types. The likelihood of this may differ by the risk of acquiring HPV infections. We examined occurrence of HPV types among vaccinated and unvaccinated subgroups of 1992-1994 birth cohorts with differing acquisition risks up to 9 years post-implementation of HPV vaccination in 33 Finnish communities randomized to: Arm A (gender-neutral HPV16/18 vaccination), Arm B (girls-only HPV16/18 vaccination and hepatitis B-virus (HBV) vaccination of boys), and Arm C (gender-neutral HBV vaccination). Out of 1992-1994 born resident boys (31,117) and girls (30,139), 8,618 boys and 15,615 girls were vaccinated, respectively, with 20-30% and 50% coverage in 2007-2009. In 2010-2013, 8,868 HPV16/18 and non-HPV vaccinated females, and in 2014-2016, 5,574 originally or later (2010-2013) HPV16/18 vaccinated females attended two cervical sampling visits, aged 18.5 and 22-years. The samples were typed for HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/66/68 using PCR followed by MALDI-TOF MS. HPV prevalence ratios (PR) between Arms A/B vs. C were calculated for Chlamydia trachomatis positives (core-group), and negatives (general population minus core group). At both visits the vaccine-protected HPV type PRs did not significantly differ between the core-group and non-core group. Among the vaccinated 18-year-olds, HPV51 occurrence was overall somewhat increased (PRcore = 1.4, PRnon-core. = 1.4) whereas the HPV52 occurrence was increased in the core-group only (PRcore = 2.5, PRnon-core = 0.8). Among the non-HPV vaccinated 18-year-olds, the HPV51/52 PRs were higher in the core-group (PRcore = 3.8/1.8, PRnon-core = 1.2/1.1). The 22-year-olds yielded no corresponding observations. Monitoring of the sexual risk-taking core-group may detect early tendencies for HPV type replacement.

Oncogenic non-vaccine human papillomavirus (HPV) types may conceivably fill the vacated ecological niche of the vaccine types. The likelihood of this may differ by the risk of acquiring HPV infections. We examined occurrence of HPV types among vaccinated and unvaccinated subgroups of 1992-1994 birth cohorts with differing acquisition risks up to 9 years post-implementation of HPV vaccination in 33 Finnish communities randomized to: Arm A (gender-neutral HPV16/18 vaccination), Arm B (girls-only HPV16/18 vaccination and hepatitis B-virus (HBV) vaccination of boys), and Arm C (gender-neutral HBV vaccination). Out of 1992-1994 born resident boys (31,117) and girls (30,139), 8,618 boys and 15,615 girls were vaccinated, respectively, with 20-30% and 50% coverage in 2007-2009. In 2010-2013, 8,868 HPV16/18 and non-HPV vaccinated females, and in 2014-2016, 5,574 originally or later (2010-2013) HPV16/18 vaccinated females attended two cervical sampling visits, aged 18.5 and 22-years. The samples were typed for HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/66/68 using PCR followed by MALDI-TOF MS. HPV prevalence ratios (PR) between Arms A/B vs. C were calculated for Chlamydia trachomatis positives (core-group), and negatives (general population minus core group). At both visits the vaccine-protected HPV type PRs did not significantly differ between the core-group and non-core group. Among the vaccinated 18-year-olds, HPV51 occurrence was overall somewhat increased (PR

With optimal strategy, human papillomavirus (HPV) vaccines have the potential to control HPV. We have assessed vaccine efficacy (VE), herd effect (HE) of HPV vaccination and overall protective effectiveness (PE) against high-risk HPV infections by HPV type and vaccination strategy in a community-randomized trial using the bivalent HPV16/18 vaccine. We randomized 33 communities to gender-neutral HPV vaccination (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Entire 1992-1995 male (40,852) and female (39,420) birth cohorts were invited, and 11,662 males and 20,513 females vaccinated with 20-30% and 45% coverage in 2007-2010. During 2010-2014, 11,396 cervicovaginal samples were collected from 13,545 18.5-year-old attendees. HPV typing was performed by a high-throughput PCR. VE was calculated for HPV vaccinated women and HE for non-HPV-vaccinated women, using the HBV vaccinated, for HE all non-HPV vaccinated, Arm C women as controls. PE was calculated as coverage rate-weighted mean of VE + HE. HPV16/18/45 and 31/33/35 VEs varied between 86-94% and 30-66%, respectively. Only the gender-neutral vaccination provided significant HEs against HPV18 (61%) and HPV31 (72%) in the 1995 birth cohort-increased HEs against HPV33 (39%) and HPV35 (42%) were also observed. Due to the increased HEs, PEs for HPV16/18/45 and HPV31/33/35 were comparable in the gender-neutral arm 1995 birth cohort. High vaccine efficacy against HPV16/18/45 and, gender-neutral vaccination-enforced, herd effect against HPV18/31/33/35 by the bivalent vaccine rapidly provides comparable overall protective effectiveness against six oncogenic HPV types: 16/18/31/33/35/45.

Efficacy of human papillomavirus (HPV) vaccines promises to control HPV infections. However, HPV vaccination programs may lay bare an ecological niche for non-vaccine HPV types. We evaluated type-replacement by HPV type and vaccination strategy in a community-randomized trial executed in HPV vaccination naïve population. Thirty-three communities were randomized to gender-neutral vaccination with AS04-adjuvanted HPV16/18 vaccine (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Resident 1992-95 born boys (40,852) and girls (39,420) were invited. 11,662 boys and 20,513 girls were vaccinated with 20-30% and 45-48% coverage, respectively. HPV typing of 11,396 cervicovaginal samples was performed by high throughput PCR. Prevalence ratios (PR) between arms and ranked order of HPV types and odds ratio (OR) for having multiple HPV types in HPV16 or 18/45 positive individuals were calculated. The ranked order of HPV types did not significantly differ between arms or birth cohorts. For the non-HPV vaccinated 1992-1993 birth cohorts increased PR, between the gender-neutral intervention versus control arms for HPV39 (PR

Objective Due to long lag time between infection/cancer diagnoses human papillomavirus (HPV) vaccination programs will deliver vaccine efficacy (VE) estimates against cancer end-points late. Cancer registry follow-up of population-based, randomised trial cohorts of vaccinated and unvaccinated women was undertaken for the estimation of VE against cervical intraepithelial neoplasia grade three and invasive cancer (CIN3+). Methods We report interim results with 98 561 person years of Finnish Cancer Registry -based follow-up of individually and/or cluster randomised cohorts of HPV-16/18 vaccinated and unvaccinated adolescent women enrolled in June 2003/2005, and between May 2004 and April 2005, respectively. The cohorts comprised 15 627 18- to 19-year-old unvaccinated women (NCT01393470), and 2 401 and 64 16- to 17-year-old HPV-16/18 vaccinated women participating the PATRICIA (NCT00122681) and HPV-012 (NCT00169494) trials, respectively. The age-aligned passive follow-up started 6 months after the clinical trials’ end. Results During the follow-up of 4.5 to 10 years post enrolment we identified 75 cases of cervical intraepithelial neoplasia grade 3 (CIN3) and 4 cases of invasive cervical cancer (ICC) in the unvaccinated cohort, and 4 CIN3 cases in the HPV-16/18 vaccinated women. Diagnostic blocks were available for HPV typing from 87% of the cases. CIN3+ lesions were detectable in 54 cases. HPV16 was found in 26 of 50 unvaccinated CIN3+ cases, and in 3 CIN3+ cases in the HPV-16/18 vaccinated women. The latter were all baseline positive for cervical HPV16 DNA. Baseline data was not available for the unvaccinated women. Intention-to-treat VE against any CIN3+ was 66% (95% CI 8, 88). Conclusions Ten years post vaccination the AS04-adjuvanted HPV-16/18 vaccine shows continued efficacy against CIN3+ irrespectively of HPV type. Vaccine efficacy was not observed in baseline HPV16 DNA positive subjects. Trial registration number NCT01393470.

The risk of seroconversion for multiple human papillomavirus (HPV) types over time was studied in a cohort of 532 women with cervical HPV infection, prospectively followed-up for >10 y. Of the women who were HPV-antibody positive for at least 1 of the HPV types (6, 11 (low risk, lr), 16, 18, 31, 33, and 45 (high risk, hr)) at baseline, 73-98% seroconverted for 1 or more HPV types over time. Baseline lrHPV-seropositive women had 2.3-fold risk (95% confidence interval (CI) 1.1-4.7) for hrHPV seroconversion, but the opposite was not the case. Cross-protection by the natural HPV16 or HPV18 infection against other types of the HPV species A9 or A7 was not seen. These data suggest that protection against other HPV genotypes (as indicated by the lack of seroconversion) may not be provided by humoral HPV antibodies derived from a natural infection. Instead, these unvaccinated, HPV-antibody-positive women continue to be susceptible to infections by the other HPV genotypes over time.

Human papillomaviruses (HPVs, most notably types 16 and 18) cause cervical carcinoma, the second most common cancer among women. Vaccination of adolescents against HPV16/18 might prevent large proportion of cervical and other anogenital cancers. However, because of ethical reasons this cannot be proven by clinical studies. To determine the long-term vaccine efficacy (VE) of HPV16/18 virus-like-particle (VLP) vaccine against cervical carcinoma in situ (CIS+) and invasive cervical carcinoma, the following three population-based cohorts of adolescent women have been enrolled: (1) women vaccinated with the HPV vaccine; (2) women vaccinated with hepatitis A control vaccine; and (3) unvaccinated control women. These cohorts will be passively followed for cumulative incidence of CIS+ endpoints by population-based cancer registry. Overall 24,046 16- to 17-year-old adolescent women from 18 cities in Finland were invited between May 2004 and June 2005 to participate in a phase III trial with bivalent HPV16/18 VLP vaccine. A total of 58,996 18- to 19-year-old women were invited in May 2005 to participate as unvaccinated controls. Women who reported their willingness to participate in an HPV vaccination trial had they been 1–2 years younger were eligible. Cumulative incidence (CI) of CIS+ in our cohorts over 15 years is approximately 0.45%. VE of 70% against CIS+ with 80% power requires 3357–3189 HPV16/18 vaccine recipients, 3357–3189 other vaccine recipients, and 6714–9567 unvaccinated controls. We have now enrolled 2404 HPV16/18 vaccine recipients, 2404 hepatitis A-vaccine recipients, and 5130 unvaccinated controls. This enrolment in addition to our earlier enrolment in another phase III trial guarantees enough power so that by 2020 we can ultimately provide data on the efficacy of HPV16/18 vaccination against CIS+.

ObjectiveDue to long lag time between infection/cancer diagnoses human papillomavirus (HPV) vaccination programs will deliver vaccine efficacy (VE) estimates against cancer end-points late. Cancer registry follow-up of population-based, randomised trial cohorts of vaccinated and unvaccinated women was undertaken for the estimation of VE against cervical intraepithelial neoplasia grade three and invasive cancer (CIN3+).MethodsWe report interim results with 98 561 person years of Finnish Cancer Registry -based follow-up of individually and/or cluster randomised cohorts of HPV-16/18 vaccinated and unvaccinated adolescent women enrolled in June 2003/2005, and between May 2004 and April 2005, respectively. The cohorts comprised 15 627 18- to 19-year-old unvaccinated women (NCT01393470), and 2 401 and 64 16- to 17-year-old HPV-16/18 vaccinated women participating the PATRICIA (NCT00122681) and HPV-012 (NCT00169494) trials, respectively. The age-aligned passive follow-up started 6 months after the clinical trials’ end.ResultsDuring the follow-up of 4.5 to 10 years post enrolment we identified 75 cases of cervical intraepithelial neoplasia grade 3 (CIN3) and 4 cases of invasive cervical cancer (ICC) in the unvaccinated cohort, and 4 CIN3 cases in the HPV-16/18 vaccinated women. Diagnostic blocks were available for HPV typing from 87% of the cases. CIN3+ lesions were detectable in 54 cases. HPV16 was found in 26 of 50 unvaccinated CIN3+ cases, and in 3 CIN3+ cases in the HPV-16/18 vaccinated women. The latter were all baseline positive for cervical HPV16 DNA. Baseline data was not available for the unvaccinated women. Intention-to-treat VE against any CIN3+ was 66% (95% CI 8, 88).ConclusionsTen years post vaccination the AS04-adjuvanted HPV-16/18 vaccine shows continued efficacy against CIN3+ irrespectively of HPV type. Vaccine efficacy was not observed in baseline HPV16 DNA positive subjects.Trial registration numberNCT01393470.

BACKGROUND: The control arm of PATRICIA (PApilloma TRIal against Cancer In young Adults, NCT00122681) was used to investigate the risk of progression from cervical HPV infection to cervical intraepithelial neoplasia (CIN) or clearance of infection, and associated determinants. METHODS AND FINDINGS: Women aged 15-25 years were enrolled. A 6-month persistent HPV infection (6MPI) was defined as detection of the same HPV type at two consecutive evaluations over 6 months and clearance as ≥2 type-specific HPV negative samples taken at two consecutive intervals of approximately 6 months following a positive sample. The primary endpoint was CIN grade 2 or greater (CIN2+) associated with the same HPV type as a 6MPI. Secondary endpoints were CIN1+/CIN3+ associated with the same HPV type as a 6MPI; CIN1+/CIN2+/CIN3+ associated with an infection of any duration; and clearance of infection. The analyses included 4825 women with 16,785 infections (3363 women with 6902 6MPIs). Risk of developing a CIN1+/CIN2+/CIN3+ associated with same HPV type as a 6MPI varied with HPV type and was significantly higher for oncogenic versus non-oncogenic types. Hazard ratios for development of CIN2+ were 10.44 (95% CI: 6.96-15.65), 9.65 (5.97-15.60), 5.68 (3.50-9.21), 5.38 (2.87-10.06) and 3.87 (2.38-6.30) for HPV-16, HPV-33, HPV-31, HPV-45 and HPV-18, respectively. HPV-16 or HPV-33 6MPIs had ~25-fold higher risk for progression to CIN3+. Previous or concomitant HPV infection or CIN1+ associated with a different HPV type increased risk. Of the different oncogenic HPV types, HPV-16 and HPV-31 infections were least likely to clear. CONCLUSIONS: Cervical infections with oncogenic HPV types increased the risk of CIN2+ and CIN3+. Previous or concomitant infection or CIN1+ also increased the risk. HPV-16 and HPV-33 have by far the highest risk of progression to CIN3+, and HPV-16 and HPV-31 have the lowest chance of clearance. ispartof: PLoS One vol:8 issue:11 ispartof: location:United States status: published

Vaccines against high-risk (hr) human papillomaviruses (HPVs) causing cervical cancer may soon be licensed. Thus, nature of HPV epidemics needs to be studied now. Random sampling for studies on HPV epidemiology was done from all 230,998 women belonging to the population-based Finnish Maternity Cohort and having a minimum of 2 pregnancies between 1983 and 1994. First pregnancy serum specimens were retrieved for 7,805 subjects, and were analyzed for antibodies to HPV6/11, 16 and 18 with standard ELISAs. HPV16 seroprevalence almost doubled from the 1980s to the 1990s, and the epidemic spread to new areas in 23-31 year olds, i.e. the bulk of pregnant female population in the southwest part of the country. The HPV16 epidemic in the 14-22 year olds in 1983-1988 (1961-1974 birth cohorts) and in the 23-31 year olds in 1989-1994 (1958-1971 birth cohorts) overlapped with strong clustering of HPV16 and HPV18 infections in the latter (odds ratio 8.0, 95% confidence interval 6.6-9.7). Similar clustering of HPV16 and HPV6/11 infections was not found. The epidemic and the clustering may be due to high transmission probability of the hrHPV types and increase in sexual activity of the index birth cohorts.

We evaluated a study setting for assessment of the long-term vaccine efficacy (VE) of human papillomavirus (HPV) virus-like-particle (VLP) vaccine against cervical carcinoma. A total of 22,412 16- to 17-year old adolescent women from seven cities in Finland were invited by letter to participate in a phase III study of a quadrivalent HPV (types 6, 11, 16, 18) VLP vaccine, between September 2002 and March 2003. A total of 30,947 18-year old women were invited to participate as unvaccinated controls. These women were asked about their willingness to participate in an HPV vaccination trial and to fill a health questionnaire. These three population-based cohorts of adolescent women, including women vaccinated with HPV vaccine or placebo vaccine and unvaccinated control women, are systematically followed over time. The study cohort database will be linked with the Finnish Cancer Registry using cervical carcinoma in situ (CIS) and invasive cervical carcinoma (ICC) as endpoints. Assuming that the cumulative incidence of CIS and ICC over 15 years is 0.45%, and that there is no loss to follow-up, and power of 80%, the determination of 70% total VE will require 3357 HPV vaccine recipients, 3357 placebo vaccine recipients, and 6714 unvaccinated controls. At the baseline, 2632 (12%) of the invited adolescents volunteered to the phase III vaccination trial, and 6790 (22%) responded to the questionnaire study. During a recruitment period of 10 months, 874 HPV vaccine recipients, 875 placebo recipients and 1919 unvaccinated controls were enrolled. Population-based enrolment of large cohorts of vaccinated and unvaccinated adolescents for passive registry-based follow-up with cervical carcinoma as the end-point is feasible and currently going on in Finland.