biostudies-literatureUnknown62Zhong GH<h4>Background</h4>Cecolin9, a second-generation 9-valent HPV vaccine derived from the WHO-prequalified Cecolin, has received marketing authorisation in China in May 2025. The non-inferiority of type-specific immune responses between Cecolin9 and Gardasil9 has been previously established at month 7 in Chinese women aged 18-26 years (NCT04782895). This study aimed to compare the plateau antibody levels between the two vaccines three years post the first dose.<h4>Methods</h4>This was a prospective extension study of a randomised, single-blind trial conducted in China (ClinicalTrials.gov, NCT06197802). All the participants included in the base study were invited to participate in this extension. Blood samples were collected at year 3 (median follow-up time of 34 months) for neutralising antibThe Lancet regional health. Western Pacific101671https://www.ebi.ac.uk/biostudies/studies/S-EPMC12408396biostudies-literatureImmunogenicity comparison of an &lt;i&gt;Escherichia coli&lt;/i&gt;-produced 9-valent human papillomavirus vaccine and Gardasil9 in Chinese women aged 18-26 years: three-year follow-up data from a randomised clinical trial.PMC12408396Chen QZhu KXZhang JZhang MLNie LLChen LZhang LLiu SXia NSLi KLi JXNie CXu JBBi ZFHuang WJQuan JLSu YYChu KQiu LXHuang SJWu TZhang QFZhong GHPan HXfalseImmunogenicity comparison of an &lt;i&gt;Escherichia coli&lt;/i&gt;-produced 9-valent human papillomavirus vaccine and Gardasil9 in Chinese women aged 18-26 years: three-year follow-up data from a randomised clinical trial.<h4>Background</h4>Cecolin9, a second-generation 9-valent HPV vaccine derived from the WHO-prequalified Cecolin, has received marketing authorisation in China in May 2025. The non-inferiority of type-specific immune responses between Cecolin9 and Gardasil9 has been previously established at month 7 in Chinese women aged 18-26 years (NCT04782895). This study aimed to compare the plateau antibody levels between the two vaccines three years post the first dose.<h4>Methods</h4>This was a prospective extension study of a randomised, single-blind trial conducted in China (ClinicalTrials.gov, NCT06197802). All the participants included in the base study were invited to participate in this extension. Blood samples were collected at year 3 (median follow-up time of 34 months) for neutralising antib2025-01-01T00:00:00Z2025 Sep2026-06-03T07:00:47.766Z2026-05-29T03:05:53.994ZS-EPMC124083964091938510.1016/j.lanwpc.2025.101671