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Safe, swift vaccine production: A triumph of science

COVID-19 vaccines are safe and effective—thanks to great science, incredible collaboration and careful approval processes.

By Elizabeth Jane Walker

To understand one of history’s most extraordinary scientific accomplishments, you need only take a look at your calendar. Two years ago, we were all blissfully unaware of COVID-19. No one had mentioned it, died of it, bought a mask to protect against it or tweeted about it.

At that time, not one scientist on the planet had researched the SARS-CoV-2 virus—because nobody knew of its existence.

By December 2019, the invisible foe had begun its stolid march around the world, wreaking unspeakable devastation. That’s when the first superheroes emerged: Scientists. In many academic institutions—including St. Jude—researchers paused crucial investigations to take aim at a common enemy. By January 2020, scientists had sequenced the virus’ genome. By fall of that year, clinical trials were underway. And by December, safe and effective vaccines were within reach.

 Today, nearly 4.5 billion vaccine doses have been given worldwide. And yet, some people continue to worry about the very aspects that made this modern marvel possible—the speed of development and streamlined production time. 


The great thing about these vaccines is that they don’t have the live, attenuated virus like we see with some other vaccines, With COVID-19, there is no live virus. So, you cannot get COVID from the vaccine.

Diego Hijano, MD, Infectious Diseases


mRNA to the rescue

In 1918, more people died of influenza than died on the battlefields of World War I. Since that time, scientists have added volumes to our knowledge about pathogens and prevention. So, when SARS-CoV-2 appeared on the horizon, we knew a thing or two about how to approach it. 

For decades, researchers have been perfecting the technology used in the Pfizer-BioNTech and Moderna SARS-CoV-2 vaccines. Instead of using an inactivated germ to prompt an immune response, the new vaccines use bits of the virus’ genetic material delivered using a different mechanism, called messenger RNA, or mRNA. When your body’s cells encounter mRNA, they create a harmless protein that generates antibodies against the virus. The mRNA never enters the cell’s nucleus, where DNA resides. After the vaccine does its work, the cell breaks down the mRNA and gets rid of it.

“The great thing about these vaccines is that they don’t have the live, attenuated virus like we see with some other vaccines,” said Diego Hijano, MD, Infectious Diseases. “With COVID-19, there is no live virus. So, you cannot get COVID from the vaccine.”

Recent mRNA advances have also resulted in vaccine platforms against several types of cancer, as well as infectious diseases such as flu, Zika virus and rabies.

infographic timeline for mRNA vaccine development

Layers of safety review 

The U.S. Food and Drug Administration (FDA) has the responsibility of making sure drugs we take are safe and effective. The FDA uses a variety of different review processes to do that. These processes may seem arcane, but they are designed to carefully evaluate drugs. 

FDA reviews include a public component in which independent experts review the data and provide advice. Clinical trials, including the COVID-19 vaccine trials, include data safety monitoring boards where experts not involved in the trial critique and review the data. The Centers for Disease Control and Prevention (CDC) also provides additional recommendations and safety monitoring processes. U.S. officials share information with European and other regulators as the vaccines continue to be used around the globe. 

EUA and you 

In an emergency situation such as a pandemic, the FDA can evaluate their review options. They could decide a different review process may be needed in order to save the most lives. The Emergency Use Authorization (EUA) involves the same thorough standards, but other resources are added to make decisions more quickly than usual. In the case of COVID-19 vaccines, studies involving more than 50,000 people showed the vaccines to be safe and effective. The EUA process is not static, and data continue to be collected and reviewed by the FDA and others. 

At one point, the CDC and the FDA paused the use of Johnson & Johnson’s Janssen vaccine, which had received emergency authorization. Officials wanted to evaluate an extremely rare side effect that affected only 7 women out of a million who received the vaccine. Once the issue had been evaluated and safety assured, the pause on the Johnson & Johnson Janssen vaccine was lifted. 

Other vaccine candidates simply didn’t make the cut. For instance, when clinical trials showed that two potential vaccines failed to provide adequate immune responses, the pharmaceutical giant Merck called a halt to its vaccine production efforts.

The FDA granted approval of the Pfizer-BioNTech COVID-19 vaccine for people ages 16 and older August 23. 

Safe and effective

According to the CDC, COVID-19 vaccines are part of the most intensive vaccine safety monitoring effort in U.S. history.

It took scientific ingenuity, collaboration and substantial funding to move the vaccines from concept to reality. Today, more than 165 million Americans are fully vaccinated. The FDA and CDC continue to carefully monitor each of the authorized COVID-19 vaccines for safety concerns.

“There have been multiple layers of review by independent safety and monitoring committees consisting of scientists, doctors and other health care providers from government and private groups,” said James Hoffman, PharmD, chief patient safety officer. Some of these systems existed before; some are newer. 

“But, each of them has been created for one reason: To ensure that the vaccines are safe and effective, which will keep us all safe from COVID-19.”