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Developing COVID-19 Vaccines
Overview
Bringing a new vaccine to the public involves many steps including vaccine development, clinical trials, US Food and Drug Administration (FDA) authorization or approval, manufacturing, and distribution. Many different public organizations and private companies have worked together to make COVID-19 vaccines available to the public. While COVID-19 vaccines have been developed rapidly, all steps have been taken to ensure their safety and effectiveness.
The Vaccine Process: From the Lab to You
New vaccines are first developed in laboratories. The virus that causes COVID-19 is related to other coronaviruses that cause diseases such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Scientists have been studying these other coronaviruses to develop vaccines against them for many years, long before SARS-COV-2 was identified. The knowledge gained through past research on coronavirus vaccines helped to accelerate the initial development of the current COVID-19 vaccines.
After initial development, vaccines go through three phases of clinical trials to make sure they are safe and effective. For other vaccines routinely used in the United States, the three phases of clinical trials are performed one at a time. During the development of COVID-19 vaccines, these phases have overlapped to speed up the process so the vaccines can be used as quickly as possible to control the pandemic. No trial phases have been skipped.
The clinical trials for COVID-19 vaccines have involved tens of thousands of volunteers of different ages, races, and ethnicities. Clinical trials for vaccines compare outcomes (such as how many people get sick) between people who are vaccinated and people who are not. Because COVID-19 continues to be widespread , the vaccine clinical trials have been conducted more quickly than if the disease were less common. Results from these trials have shown that COVID-19 vaccines are effective. They have also shown no serious safety concerns after more than 8 weeks following vaccination. This is an important milestone, as it is unusual for adverse effects caused by vaccines to appear after this amount of time.
Before vaccines are made available to people in real-world settings, FDA assesses the findings from clinical trials. So far, they have determined that three COVID-19 vaccines meet FDA’s safety and effectiveness standards and have granted those vaccines Emergency Use Authorizations (EUAs)external icon. The EUAs have allowed the vaccines to be quickly distributed for use while maintaining the same high safety standards required for all vaccines. Learn more in this video about EUAs.
The US government has invested substantial resources for both manufacturing and distribution of COVID-19 vaccines. This has allowed manufacturing to begin when the vaccines are still in the third phase of clinical trials so that distribution can begin as soon as the FDA has authorized each vaccine.
As vaccines are distributed outside of clinical trials, several monitoring systems continue to track them to ensure their safety. Millions of people have received COVID-19 vaccines, and results from ongoing vaccine safety monitoring efforts are reassuring. Some people have no side effects. Many people have reported mild side effects after COVID-19 vaccination, like pain or swelling at the injection site, a headache, chills, or fever. These reactions are common. A small number of people have had a severe allergic reaction (called “anaphylaxis”) after vaccination, but this is extremely rare. If this occurs, vaccination providers have medicines available to treat the reaction effectively and immediately.
No unexpected patterns of reactions or other safety concerns have been identified during early vaccine safety monitoring. CDC and FDA continue to closely monitor several reporting systems, like the Vaccine Adverse Event Reporting System (VAERS), Vaccine Safety Datalink (VSD), and v-safe, which help look for any safety issues now that the vaccines are being given to patients in real-world settings across the country.
What This Means for You
COVID-19 vaccines have been rapidly developed and distributed to help fight the pandemic. During this process, all steps have been taken to ensure their safety and effectiveness. CDC recommends you get a COVID-19 vaccine as soon as it is available to you so you can protect yourself and others.
- Common Questions People May Ask About COVID-19 Vaccines pdf icon[217 KB, 2 Pages]
- Answering Your Questions About the New COVID-19 Vaccines pdf icon[367 KB, 4 Pages]
- COVID-19 Vaccine Basics: What Healthcare Personnel Need to Know pdf icon[1.29 MB, 23 Pages]
- COVID-19 Vaccination Communication Toolkit
- COVID-19 Clinical Resources
- COVID-19, MERS & SARSexternal icon
- Time Saved pdf icon[779 KB, 1 Page]external icon
FDA infographic on how time was saved in the vaccine development process