Science Buddies: "Ask an Expert"

Hello. I have the following question: why are we able to produce vaccines against a lot of viruses and much less against bacteria? I find it very impressive that vaccines work even for lokalised infections without systemic manifestations/inflammation, such as HPV vaccine for cervical infection.

Hello,
The Science Buddies Ask the Expert forum is for students in grades K-12 who are doing science projects. If you are a student in grades K-12 and are doing a science project, please provide more detail about your project, including your hypotheses and how you plan to conduct experiments to test your hypotheses. If you are not a student, there are other sites on the web where your questions would be more appropriate. Thank you.