How Vaccines are Developed

Vaccines help protect us from many diseases, making our lives much happier and healthier. Have you ever wondered what it takes to create and get approval for a vital new vaccine, such as one for COVID-19?

A Step-by-Step Process

Getting approval for a new vaccine requires rigorous testing to ensure the vaccine’s safety and effectiveness. The step-by-step process includes:

1. Exploratory and Preclinical Research. In the earliest stages of development, lab scientists conduct basic research — such as exploring the feasibility of a vaccine to address a new disease begin with. If a vaccine is thought to be a viable solution, a candidate vaccine may then be studied in cell or tissue cultures, or in animals.

2. Clinical Trials. Next, if approved by the U.S. Food and Drug Administration (FDA), a promising vaccine may be studied in people. Among other things, scientists will assess the vaccine's safety and ability to provide immunity, the number of doses needed, and any potential side effects.

Most clinical trials happen in three phases:

  • Phase 1: The vaccine is given to a small group of adult volunteers. (Later, children also may get the trial vaccine, if it is intended for them, after it is first tested in adults.)
  • Phase 2: The vaccine is given to hundreds of people, and some of the participants are similar to those for whom the new vaccine is intended. These trials are randomized and well controlled and include a placebo group.
  • Phase 3: The vaccine is given to thousands of people and compared to a placebo. The trials are randomized and double blind — meaning that neither the trial participants nor the health officials know which participants are receiving the vaccine and which are receiving the placebo.

3. A New Vaccine is Ready. Once the clinical studies are complete, a successful candidate vaccine may be licensed for use if it is found to be safe and effective, and if its benefits outweigh the potential side effects.

4. Ongoing Monitoring. Even after a new vaccine is licensed, the FDA will continue to monitor it for safety. This includes periodic inspections of the vaccine maker's production facilities. In addition, the FDA and the Centers for Disease Control and Prevention (CDC) track side effects linked to the new vaccine that get reported by individuals, and doctors.

How Long Does this Process Take?

Vaccines often take several years to develop. But, as we've seen with efforts to develop a COVID-19 vaccine, the process can sometimes be fast-tracked.

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