The nine-valent vaccine generally refers to the nine-valent cervical cancer vaccine. The current age limit for vaccination in China is 16-26 years old, and the nine-valent cervical cancer vaccine is currently not allowed in China if you are younger than 16 years old, or older than 26 years old. In addition to the nine-valent cervical cancer vaccine, the bivalent cervical cancer vaccine is currently available for ages 9-45, and the quadrivalent cervical cancer vaccine is currently available for ages 20-45. The nine-valent cervical cancer vaccine reduces the virulence of the HPV virus and is able to prevent more than 90% of cervical cancers. The age limit for this vaccine is due to the fact that most women over 26 years old have a history of HPV exposure, on the other hand, most clinical trials of this vaccine in China have been conducted among women aged 16-26 years old, and the research data can prove the safety and efficacy of this vaccine in the age group of 16-26 years old. The bivalent cervical cancer vaccine targets HPV types 16 and 18, the quadrivalent cervical cancer vaccine targets HPV types 16, 18, 6 and 11, while the nine-valent cervical cancer vaccine targets a wider range of virus types and provides a broader scope of protection. There are two types of HPV vaccine: high-risk and low-risk, and persistent infection of high-risk viruses may cause cervical cancer. Among the high-risk viruses, the main ones are HPV type 16 and 18. Whether it is bivalent, quadrivalent or nine-valent cervical cancer vaccine, it can provide better protection against HPV type 16 and 18.