How Do We Know the COVID-19 Vaccines Are Safe and Effective? One Expert Explains.
A doctor and infectious diseases expert shares what she tells her patients.
This article was published in December 2020. Since then, millions of people have received COVID-19 vaccines, and studies continue to show the vaccines are safe and effective. Dr. Shana Miles and her children have received all the recommended vaccines and booster shots. Read the latest information on COVID-19 vaccines.
As a doctor, I’ve been hearing a lot of talk about vaccines for the coronavirus (COVID-19). Some of my patients say they wish they could be first in line to get a vaccine. They’re looking forward to protecting their families from the virus, returning to work, and getting their kids back in school.
Other patients seem unsure about getting a vaccine. And I understand there are questions out there that might make them feel this way. There are some questions we just don’t have clear answers to yet. (See this page for what we know now about the vaccines and pregnancy.) After all, we’re still learning about the different vaccines made by different manufacturers.
But there is a lot we do already know. Here, I’ll tell you what I tell my patients: how we know these vaccines will be safe, how well they’re expected to work, and why I’m excited for my own family to be vaccinated.
The journey of a vaccine
First, it helps to understand all the steps vaccines go through before they are given to the public. There are many layers of testing and review to check that vaccines work and will be safe. These are just a few of the steps required for all vaccines in the United States, including the COVID-19 vaccines:
Once scientists design the basic approach for a new vaccine, tests with animals and then small groups of human volunteers begin. These tests help scientists understand the safety of the vaccine, the right dose, and whether the vaccine seems to work as expected. The tests with people are called clinical trials.
If all goes well, then larger clinical trials begin – studies with thousands of volunteers. Some of the volunteers get the vaccine and some get a placebo (an injection that looks the same but has no effect). Scientists then track all the volunteers and compare the two groups over time. They look to see whether the people who got the vaccine were better protected against the disease. They also confirm there are still no safety concerns.
If the clinical trials show the vaccine is safe and effective, there are another few layers of safety checks. Different committees of vaccine experts meet to review the data. These reviews are done by experts who were not involved in making the vaccine, so they are not biased.
Finally, a committee considers all of the findings and advises the U.S. Food and Drug Administration (FDA) on whether to approve the vaccine. After careful review, the FDA decides whether the vaccine should be approved. During a public health crisis, the FDA can approve vaccines with an “emergency use authorization,” or EUA. This is faster than the typical approval process, but it still requires high standards and strict safety criteria.
Only the best vaccines make it through all of these steps. Others get weeded out along the way and are never considered for approval.
So rest assured: Any vaccine that you are offered has gone through a great amount of testing and oversight. The COVID-19 vaccines are no exception.
Working smarter and faster
You may have heard that the COVID-19 vaccines were developed in record time. I know this is a real concern for some people. How has this happened so quickly? Here are a few factors that speed up the process without cutting corners:
Since COVID-19 is a global health crisis, there has been a huge sharing of information among scientists, governments, and industry partners around the world. We’ve never seen this level of global cooperation before. It has helped everyone make faster progress and smarter decisions.
Governments made changes to make the process more efficient. For example, a lot more funding than usual was provided to speed along the vaccine development. Meetings to review the studies were scheduled much faster than normal.
At the same time, there are some new quality controls added for the COVID-19 vaccines. For example, new tools and systems in development will help with ongoing safety checks as people get vaccinated.
Really, this has been an amazing process to watch unfold. Without these changes, vaccines for COVID-19 would not have been ready for many years.
FDA officials set a goal for how well COVID-19 vaccines should work. They want the vaccines to protect at least 50 percent of the people who receive it, by preventing disease or reducing symptoms. So far, the results we’ve seen from the large clinical trials have gone far above that goal.
Several vaccine manufacturers have shared results as their studies unfold, and some of the vaccines’ efficacy rates have been around 95 percent. This means that among people who were given these vaccines in the trials, more than 9 in 10 were protected from the coronavirus. This is exciting news.
Of course, we will learn more about the vaccines over time. We don’t know, for example, exactly how long the vaccines will protect you from the coronavirus. But even with just the data we have now, we can be confident that the vaccines will prevent many hospitalizations and deaths.
My own family
I am the mom of two young boys. I plan to get a COVID-19 vaccine as soon as one is offered to me. So does my husband. And when a vaccine becomes available for children, my boys will be vaccinated too.
I say this without hesitation, because I know the vaccines were made, tested, and approved with a process I can trust. And I’ve seen firsthand the dangers of COVID-19. I have close friends and family members who have been infected. They were young and otherwise healthy people who got very sick from the coronavirus. Some of my friends were avid hikers and marathon runners before COVID-19, and now they can barely get up a flight of stairs.
Beyond the immediate disease risks, there’s a lot we don’t know about how COVID-19 may affect your body in the long run. So if I can give my boys a vaccine that might prevent unknown long-term problems, I will absolutely do that.
But my plan to get the vaccine goes beyond my concern for my family. I want to be part of the solution to end this pandemic. I want to help get all of our families out of quarantine and our children back into schools. I want to help relieve the stress on our hospitals, our economy, and our country.
This will only happen if enough people get the vaccine. The more people who get vaccinated, the sooner we’ll be able to start returning to our normal lives.
It may be hard to imagine life without fear of the virus. But because we know the COVID-19 vaccines will be safe and effective, we know we’re on the path to get there.
Published: December 2020
Last reviewed: September 2022
Copyright 2023 by the American College of Obstetricians and Gynecologists. All rights reserved. Read copyright and permissions information.
This information is designed as an educational aid for the public. It offers current information and opinions related to women's health. It is not intended as a statement of the standard of care. It does not explain all of the proper treatments or methods of care. It is not a substitute for the advice of a physician. Read ACOG’s complete disclaimer.