As an adult, you still need vaccinations to protect against certain diseases. You should have a flu shot every year to protect yourself against several strains of the influenza virus. If you decide to get the HPV vaccine, you will need three doses to protect yourself against human papillomavirus. The vaccination for hepatitis A is two doses, while the vaccination against hepatitis B consists of three doses. You may also need to be vaccinated against shingles, chickenpox, pneumonia, or meningitis