Public Health Madison & Dane County

The news that so many have waited for this year has arrived: A COVID-19 vaccine has been authorized for use. We know there’s a lot of information flying around about the vaccine and about the authorization process that got us to this point, and that it can be confusing. Here’s a breakdown.

How are vaccines developed?

All vaccines, when developed, go through trial phases. In those phases, the researchers recruit people to try the vaccine. The COVID-19 vaccine process moved quickly, but no phases were skipped.

Phases of development

In phase 1 of vaccine trials the researchers give the vaccine to a small number of volunteers, usually less than 100. They determine if the vaccine is safe, but they also find out if they’ve given the right dosage, and if there are any serious side effects.

In phase 2, after determining in phase 1 that there were no serious side effects, researchers look to see if the vaccine works. They give it to hundreds of people and typically add a control group who gets a placebo instead of the vaccine. This phase continues to shed light on the best dosage, the safety of the vaccine, and the addition of the control group helps to prove that the vaccine works to prevent disease.

In phase 3, the vaccine is given to tens of thousands of people to fully determine if it works and if it is safe. It’s the last step before applying for approval to be used from the Food and Drug Administration (FDA). A control group is used to help researchers compare how many people who got the vaccine got sick compared to how many people who got the placebo from the control group got sick. That tells them how effective the vaccine is at preventing the disease. In this phase, because the group size is so large, the group is much more diverse, which helps find less common side effects, confirms safety and that it works well for everyone.

Phase 4 Safety monitoring doesn’t stop when the vaccine is approved. Phase 4 allows safety monitoring to still occur even when many people are getting the vaccine.

Ensuring safety

Sometimes, as in the case of the COVID-19 pandemic, a vaccine needs to be developed quickly. It’s normal to feel some hesitancy about a new vaccine. This process is happening very fast, but there are steps in place to make sure the vaccine is safe.

In order for a vaccine to be approved by the Food and Drug Administration (FDA), an Institutional Review Board (IRB) assures that steps are taken to protect the rights and welfare of the people participating in the research.

Emergency Use Authorization (EUA)

You’ve been hearing that the Pfizer vaccine was authorized by Emergency Use Authorization (EUA), but what does that mean? An EUA is a type of authority by the FDA to allow use of medical products to prevent serious or life-threatening diseases when certain safety criteria are met and there are no alternatives.

The Pfizer COVID-19 vaccine was just authorized for use through this mechanism. While it was developed quickly, safety steps were not skipped. When an EUA is submitted to the FDA it includes safety data from both phase 1, 2 and3. The phase 3 data includes follow up at least 2 months after participants have received both doses of vaccine.

So what were all the steps in the process of authorizing this new vaccine?

• The EUA was submitted to the FDA and it was approved.
• The FDA signed the EUA.
• The Advisory Committee on Immunization Practices (ACIP) voted to authorize the vaccine for use.
• Finally, the director of the Centers for Disease Control (CDC) signed off, as the final authorization.

What’s Next?

So there you have it. That’s how the first COVID-19 vaccine was authorized for use in the United States. Next up? Getting vaccine distributed to states, where distribution to the first tier, or group of people, will begin. Stay tuned for details on that in a future blog!