MODEL RELEASED. Adult vaccination. Nurse's hand injects vaccine into the arm of an adult man. Vaccines are killed or weakened doses of microorganisms injected into the body to stimulate the immune system. They provide protection against many infectious diseases. This man may be receiving a tetanus vaccine. Children are routinely vaccinated against tetanus but booster vaccinations are recommended every 10 years in adults. The man might alternatively be receiving vaccines in preparation for a foreign holiday. Yellow fever, hepatitis A and typhoid are some of the diseases for which protection is often needed.