Safety Trials

FDA Phase 1 Clinical Trials

Typical size

20-100 volunteers

Focus

Researchers continue to ask basic safety questions and identify whether the vaccine produces an immune response. They watch for serious side effects. If side effects are noticed, they look at whether the dose (amount or concentration) changes the side effects observed.

Oversight

Each clinical trial has a Data Safety Monitoring Board (DSMB). This group is made up of non-governmental and non-industry healthcare providers, vaccine experts, immunologists and statisticians. This group can pause, modify or stop a study if they are worried about safety or how well the vaccine is working FDA provides regulatory oversight.

Expanded Trials

FDA Phase 2 Clinical Trials

Typical size

Hundreds of volunteers

Focus

Researchers continue to ask whether the vaccine is safe and produces an immune response. They watch for serious side effects. In this phase researchers begin to determine whether the immune response is strong enough to create immunity by looking at antibody levels. The larger group size allows researchers to start comparing and contrasting how well the vaccine works in different groups, such as men and women, racial and ethnic groups, and people of different age groups.

Oversight

Each clinical trial has a Data Safety Monitoring Board (DSMB). This group is made up of non-governmental and non-industry healthcare providers, vaccine experts, immunologists and statisticians. This group can pause, modify or stop a study if they are worried about safety or how well the vaccine is working. FDA provides regulatory oversight.

Efficacy Trials

FDA Phase 3 Clinical Trials

Typical size

Hundreds to thousands of volunteers

COVID Vaccine Trial

Many of the COVID-19 vaccine trials are much larger than a typical phase 3 clinical trial, with some studies enrolling as many as 30,000 to 60,000 volunteers.

Focus

Scientists give the vaccine to thousands of people and wait to see how many become infected, compared with volunteers who received a placebo. These trials can determine if the vaccine protects against the coronavirus in large numbers of people. In June, the FDA advised vaccine makers that they would want to see evidence that vaccines can protect at least 50% of those who receive it. In addition, Phase 3 trials are large enough to reveal evidence of relatively rare side effects that might be missed in earlier studies.

Oversight

Each clinical trial has a Data Safety Monitoring Board (DSMB). This group is made up of non-governmental and non-industry healthcare providers, vaccine experts, immunologists and statisticians. This group can pause, modify or stop a study if they are worried about safety or how well the vaccine is working. FDA provides regulatory oversight.

Approval Process

If successful, the vaccine maker submits a license application to FDA that provides efficacy and safety information FDA makes a risk/benefit assessment and decides whether to recommend or oppose the approval of a vaccine. Also, during this stage, the proposed manufacturing facility undergoes a pre-approval inspection during which production of the vaccine as it is in progress is examined in detail.

Following FDA's review of a license application, the vaccine maker and FDA may present their findings to the Vaccines and Related Biological Products Advisory Committee (VRBPAC). This committee is a group of non governmental and non-industry scientists, physicians, statisticians, and a consumer representative that provides advice to the FDA regarding the safety and efficacy of the vaccine for the proposed use.

Vaccine approval also requires that the product be labeled to allow health care providers to understand the vaccine's proper use, including its potential benefits and risks, to safely deliver the vaccine to the public. The vaccine and the manufacturing processes are approved by FDA during a pandemic. A vaccine may receive an Emergency Use Authorization (EUA) before getting approval. Once a vaccine is licensed, researchers continue to monitor people who receive it to make sure it Is safe and effective.

CDC Recommendation

Once FDA approves a vaccine, the U.S. Centers for Disease Control and Prevention provides guidance on whether and how products should be used by public health. CDC guidance is informed by an outside advisory committee called the Advisory Committee on Immunization Practices (ACIP). ACIP independently reviews the vaccine safety and efficacy data, as well as epidemiologic data describing which groups are most at risk and likely to benefit from vaccination.

Vaccine Adverse Event Reporting System (VAERS)

The government uses the Vaccine Adverse Event Reporting System to identify problems after a vaccine is given to the public. This system allows additional formal studies on a vaccine to continue once it is on the market. Unlike other medications and devices, vaccines are closely monitored for safety and effectiveness after they become available to the public. VAERS is one of multiple monitoring systems used to monitor vaccine safety.