An observational study in Human Papillomavirus Infection, sponsored by Shanghai Zerun Biotechnology Co.,Ltd. Active, not recruiting at 2 sites in China. Open to female participants aged 16 Years to 34 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-17.
Sponsored by Shanghai Zerun Biotechnology Co.,Ltd · Observational
This long-term extension study evaluates the persistence of neutralizing antibody responses to a bivalent human papillomavirus vaccine in females who previously participated in study 311-HPV-1004 (NCT02740777). Participants belonged to one of three vaccination cohorts in the base study: adolescents who received two doses at Months 0 and 6, adolescents who received three doses at Months 0, 2, and 6, and adults who received three doses at Months 0, 2, and 6. No vaccine is administered in the extension study. Blood samples are collected at Months 84, 108, and 132 after the first dose in the base study and tested for HPV-16 and HPV-18 neutralizing antibodies using a high-throughput pseudovirus-based neutralization assay.
576 studies on the registry are indexed under Papillomavirus Infections; 132 are open to participants now.
This study's enrollment of 348 is below the median of 490 across 157 observational studies indexed under Papillomavirus Infections.
Browse Papillomavirus Infections studies →Shanghai Zerun Biotechnology Co.,Ltd is the lead sponsor of 14 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
Females previously enrolled in study 311-HPV-1004 (NCT02740777) at the Hezhou and Zhongshan study sites in Guangxi, China, who completed the required blood-collection visits in the base study and met the eligibility criteria for the extension study.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants who were aged 9 to 14 years at enrollment in the base study and received the bivalent HPV vaccine at Months 0 and 6. No vaccine is administered in the extension study.
Biological: Bivalent Human Papillomavirus Vaccine (Types 16 and 18, Pichia pastoris)
Participants who were aged 9 to 14 years at enrollment in the base study and received the bivalent HPV vaccine at Months 0, 2, and 6. No vaccine is administered in the extension study.
Biological: Bivalent Human Papillomavirus Vaccine (Types 16 and 18, Pichia pastoris)
Participants who were aged 18 to 26 years at enrollment in the base study and received the bivalent HPV vaccine at Months 0, 2, and 6. No vaccine is administered in the extension study.
Biological: Bivalent Human Papillomavirus Vaccine (Types 16 and 18, Pichia pastoris)
Each 0.5 mL dose contained 40 micrograms of HPV-16 L1 virus-like particles and 20 micrograms of HPV-18 L1 virus-like particles adsorbed to aluminum phosphate. The vaccine was administered only in the base study 311-HPV-1004; no study vaccine is administered in 311-HPV-1004-EXTEND.
Geometric Mean Titer of HPV-16 Neutralizing Antibodies
The geometric mean and two-sided 95% confidence interval of HPV-16 neutralizing antibody titers are summarized separately for each prior-vaccination cohort using the high-throughput pseudovirus-based neutralization assay.
Time frame: Months 84, 108, and 132 after the first dose in the base study
Geometric Mean Titer of HPV-18 Neutralizing Antibodies
The geometric mean and two-sided 95% confidence interval of HPV-18 neutralizing antibody titers are summarized separately for each prior-vaccination cohort using the high-throughput pseudovirus-based neutralization assay.
Time frame: Months 84, 108, and 132 after the first dose in the base study
Seropositivity Rate for HPV-16 Neutralizing Antibodies
The percentage of participants meeting the assay-defined seropositivity threshold for HPV-16 neutralizing antibodies and its exact two-sided 95% confidence interval are summarized separately for each prior-vaccination cohort.
Time frame: Months 84, 108, and 132 after the first dose in the base study
Seropositivity Rate for HPV-18 Neutralizing Antibodies
The percentage of participants meeting the assay-defined seropositivity threshold for HPV-18 neutralizing antibodies and its exact two-sided 95% confidence interval are summarized separately for each prior-vaccination cohort.
Time frame: Months 84, 108, and 132 after the first dose in the base study
Geometric Mean Titer of HPV-16 Neutralizing Antibodies in Stored Serum Samples
The geometric mean and two-sided 95% confidence interval of HPV-16 neutralizing antibody titers measured using the high-throughput pseudovirus-based neutralization assay are summarized separately for each prior-vaccination cohort using available stored serum samples collected in the base study from participants who subsequently enrolled in the long-term extension study.
Time frame: Before the first dose on Day 0 and at Months 7, 12, 24, and 36 after the first dose in the base study
Geometric Mean Titer of HPV-18 Neutralizing Antibodies in Stored Serum Samples
The geometric mean and two-sided 95% confidence interval of HPV-18 neutralizing antibody titers measured using the high-throughput pseudovirus-based neutralization assay are summarized separately for each prior-vaccination cohort using available stored serum samples collected in the base study from participants who subsequently enrolled in the long-term extension study.
Time frame: Before the first dose on Day 0 and at Months 7, 12, 24, and 36 after the first dose in the base study
Seropositivity Rate for HPV-16 Neutralizing Antibodies in Stored Serum Samples
The percentage of participants meeting the assay-defined seropositivity threshold for HPV-16 neutralizing antibodies and its exact two-sided 95% confidence interval are summarized separately for each prior-vaccination cohort using available stored serum samples collected in the base study from participants who subsequently enrolled in the long-term extension study.
Time frame: Before the first dose on Day 0 and at Months 7, 12, 24, and 36 after the first dose in the base study
Seropositivity Rate for HPV-18 Neutralizing Antibodies in Stored Serum Samples
The percentage of participants meeting the assay-defined seropositivity threshold for HPV-18 neutralizing antibodies and its exact two-sided 95% confidence interval are summarized separately for each prior-vaccination cohort using available stored serum samples collected in the base study from participants who subsequently enrolled in the long-term extension study.
Time frame: Before the first dose on Day 0 and at Months 7, 12, 24, and 36 after the first dose in the base study
Plan to share: No — Individual participant data are not planned to be shared.
Started Mar 2023 (actual). Primary completion is estimated for Apr 2027, 49 months after the start.
Of 66 observational studies under Papillomavirus Infections, half reached primary completion within 46 months of starting (the median), counting those still running; a quarter within 24 and three quarters within 90. This study's planned 49 months is close to that.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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