Currently, the nine-valent vaccine usually requires three injections to achieve a better preventive effect. Nine-valent vaccine usually refers to the HPV (human papillomavirus) 9-valent vaccine, which is a vaccine capable of preventing human papillomavirus infection. The vaccine is relatively widely used in clinical practice and is suitable for people aged 16 to 26 years old, and is usually maintained in the body for about 5 to 20 years. The nine-valent vaccine is capable of preventing infection with a wide range of HPV subtypes, such as high-risk types of HPV16 and HPV18, as well as some low-risk subtypes of the virus. The vaccine works by stimulating a cellular immune response to clear virus-infected or mutated cells. The nine-valent vaccine usually requires three injections to achieve a better preventive effect. Before the injection, you should undergo a detailed physical examination and judge whether you are suitable for the injection according to the results and the doctor’s guidance.