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Safety of the COVID-19 vaccines


Content Reviewers:

Rishi Desai, MD, MPH

There’s a lot of pressure on researchers and pharmaceutical companies to create a vaccine for COVID-19.

You might be wondering, how can we be sure that the vaccine will be safe?

To start, this isn’t the first time we’ve made a vaccine.

There are currently over 50 vaccines covering 26 diseases used within the United States alone.

Many of the candidate COVID-19 vaccines being tested right now are based on the ideas and technology used to make vaccines that are already approved.

This is how in the span of just a few months we’ve had so many vaccines enter preclinical and clinical trials.

Researchers are not starting from scratch.

In addition, the Food and Drug Administration (also called the FDA) in the United States has given specific guidelines to researchers on how to develop COVID-19 vaccines.

Once we have a candidate vaccine, researchers subject that vaccine to a gauntlet of animal and clinical trial tests, to ensure that it’s both safe and effective.

Researchers initially test candidate vaccines on animals first in preclinical trials, and if testing goes well, the candidate vaccine can begin human clinical trials, starting with Phase I, then Phase II, and finally Phase III.

With each phase, more and more participants are recruited to be vaccinated with the candidate vaccine.

Researchers want to test the vaccine in a large and diverse group of people, to make sure that it’s safe and effective for the whole population.

Researchers need to test the candidate vaccine in people who differ in age, sex, race, and exisiting health status, like people who have asthma or are pregnant.

If a candidate vaccine successfully passes Phase III clinical trials, that means researchers are very confident the vaccine will be effective for everyone.

As of October 1st, 2020, there are 10 COVID-19 vaccines currently in Phase III trials, 13 in Phase II, 17 in Phase I, and 151 in preclinical trials.

That’s a lot of vaccines, but that’s on purpose.