Developing COVID-19 Vaccines

The vaccination process: from the laboratory to you

First development

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 Eastern Respiratory Syndrome (MERS). Scientists spent many years studying these other coronaviruses developing vaccines against them long before SARS-COV-2 was identified. The knowledge gained through previous research on coronavirus vaccines helped accelerate the initial development of the current COVID-19 vaccines.

Clinical trials

Once developed, vaccines go through three phases of clinical trials to ensure they are safe and effective. For other vaccines routinely used in the United States, the three phases of clinical trials are carried out sequentially. During the development of COVID-19 vaccines, these phases have overlapped to expedite the process so that the vaccines can be used as soon as possible to fight the pandemic. No test phases were skipped.

The clinical trials for COVID-19 vaccines involved tens of thousands of volunteers of various ages, races, and ethnicities. Vaccine clinical trials compare results (such as how many people get sick) between vaccinated and unvaccinated people. With COVID-19 remaining widespread, vaccine clinical trials have been conducted faster than if the disease were less common. The results of these studies have shown that COVID-19 vaccines are effective. You have not shown any serious safety concerns even more than 8 weeks after vaccination. This is an important milestone as it is uncommon for vaccine-induced side effects to occur after this time.

Emergency approval

Before vaccines are made available to humans in real-world environments, the FDA evaluates the results of clinical trials. So far, they have determined that three COVID-19 vaccines meet FDA safety and efficacy standards and have issued Emergency Use Authorizations (EUAs) to those vaccines.external symbol

Manufacturing and distribution

The U.S. government has invested significant funds in both the manufacture and distribution of COVID-19 vaccines. That way, when the vaccines are still in the third phase of clinical trials, manufacturing has been able to begin, so distribution can begin as soon as the FDA clears each vaccine.

Tracking safety using vaccine monitoring systems

As vaccines are marketed outside of clinical trials, multiple surveillance systems continue to track them to ensure their safety. Millions of people have received COVID-19 vaccines and the results of ongoing efforts to monitor vaccine safety are reassuring. Some people have no side effects. Many people have reported mild side effects such as pain or swelling at the injection site, headache, chills, or fever after receiving the COVID-19 vaccination. These reactions are common. A small number of people have had a severe allergic reaction (called 'anaphylaxis') after vaccination, but it is extreme Rare. In this case, medication is available to vaccination providers to effectively and promptly treat the reaction.

No unexpected reaction patterns or other safety concerns were identified during the early monitoring of vaccination safety. The CDC and FDA continue to closely monitor multiple reporting systems, such as the Vaccine Adverse Event Reporting System (VAERS), Vaccine Safety Datalink (VSD), and v-safe, which help identify safety issues once the vaccines are administered to patients in real-world environments throughout the country.

What this means for you

COVID-19 vaccines were quickly developed and distributed to fight the pandemic. During this process every step has been taken to ensure its safety and effectiveness. CDC recommends that you get a COVID-19 vaccine as soon as it becomes available so that you can protect yourself and others.