You will find hundreds of articles, studies, research that shows the American Academy of Pediatrics, the American Medical Association, the CDC, the EPA, scientists, doctors, pharmacists around the world all agree that vaccines are safe. Most vaccines have a protective effect through not only protecting you, but it also protects the population through something called "herd immunity." Herd immunity describes when a high percentage of the population is protected through vaccination against a virus or bacteria such as the flu, and this makes it difficult for a disease to spread. It makes sense as the more people who are vaccinated, the chances of spreading the flu are less likely. This is one of the many reasons why a vaccine is recommended.