Types of Vaccines
Biological preparations which provides active acquired immunity to a particular disease is known as Vaccines. Vaccines contain a microorganism in a weakened or killed state, or proteins or toxins from the organism. Vaccines can be prophylactic or therapeutic. The World Health Organization (WHO) reports that currently, licensed vaccines are available for twenty-five different preventable infections. For example, vaccines that have proven effective include the influenza vaccine, HPV vaccine and chicken pox vaccine.