Vaccine development typically begins not at a pharmaceutical company, but in a research laboratory in a university, medical center or small biotech company. During this time, several different scientists or groups of scientists may be working toward the same goal: developing a vaccine against a certain virus or bacteria.

By the time a vaccine is offered to the public, it has been studied for at least 15 to 20 years in tens of thousands of study participants, by thousands of scientists, statisticians, health care providers and other personnel, and has cost at least $1 billion dollars to produce.

Currently, the United States has the safest, most effective vaccine supply in its history. Clinical trials are conducted to evaluate the safety and effectiveness of a vaccine before it can be brought to market. Vaccines are first tested in laboratory studies and animal studies. If the results indicate the vaccine is safe, additional testing in people must be done before the vaccine can be approved by the Food and Drug Administration (FDA).

Many potential vaccines that never go beyond the research stage. Scientists and researchers are constantly evaluating a product during the trials to determine whether they are worth pursuing. Many ideas are abandoned during the different trial phases.

Learn more about each stage of the vaccine development process and how vaccines are licensed.

See the CDC infographic: The Journey of Your Child’s Vaccine.

CDC: Vaccine Testing and the Approval Process
Children’s Hospital of Philadelphia: Process of Vaccine Development
Children’s Hospital of Philadelphia: Licensure, Recommendations and Requirements