Vaccine Safety & Effectiveness

The vaccines authorized for use in the U.S. are highly safe and effective. All three vaccines were developed in the United States and have undergone U.S. Food and Drug Administration (FDA) scrutiny, the most rigorous vaccine approval process on the planet. They were found to be up to 95% effective in adults, and some clinical trial participants experienced mild to moderate side effects attributable to a normal, healthy immune response.
“We are committed to expediting the development of COVID-19 vaccines, but not at the expense of sound science and decision making. We will not jeopardize the public’s trust in our science-based, independent review of these or any vaccines. There’s too much at stake.”

Stephen M. Hahn, M.D., FDA Commissioner, and Peter Marks, M.D., Ph.D., Director, Center for Biologics Evaluation and Research

Vaccine Development & Approval Process

Each COVID-19 vaccine moved through a three-phase development process, including human clinical trials involving tens of thousands of people. Upon the completion of the clinical trials, the drug sponsors applied to the FDA to market and distribute the vaccine.

Prior to issuing guidance on each vaccine, the data and evidence was reviewed by an external panel of independent experts who provided a recommendation to the FDA to authorize the vaccine. The FDA ultimately determined that the safety and effectiveness of the vaccines, product quality, and consistency had been clearly demonstrated, so the vaccines were authorized. While the three-phase clinical trial process has historically taken an average of three years or more, the FDA allowed for the acceleration of the development timeline and permitted some trials to overlap rather than run sequentially.

But federal oversight does not end once the vaccines are authorized. Local healthcare workers have been among the first to receive the vaccine and they are using an after-vaccine health checker to provide additional data to a national database. Anyone who gets the vaccine may also use the vaccine reporting system – VAERS – to report undocumented side effects. This system is already used with other vaccines and immediately alerts health authorities to any possible issues.

Visit the FDA’s website to learn more about the development of the COVID-19 vaccines.

Side Effects

In clinical trials for all three COVID-19 vaccines available in the U.S., short-term side effects were common, but most were mild to moderate. Some people had no side effects. Common side effects include:

  • Chills
  • Fever
  • Fatigue
  • Headache
  • Nausea
  • Pain, redness or swelling at the injection site
  • Joint and muscle pain

Side effects from vaccines are not uncommon. The seasonal flu shot, for example, can cause fever and fatigue, among other symptoms.

The COVID-19 vaccines, in particular, are designed to teach your body how to recognize and fight the coronavirus. Therefore, mild to moderate side effects are the result of a normal, healthy immune system responding to the vaccine.

Side effects do not mean you have contracted COVID-19. You cannot get COVID-19 from the vaccine. Remember, mild to moderate symptoms are a sign that the body is building immunity.

Visit the Centers for Disease Control and Prevention website to learn more about the COVID-19 side effects.