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The science behind COVID-19 vaccines

By Jennifer Robinette

It may seem like the COVID-19 vaccine moved quickly to emergency use authorization and approval. But the reality is researchers and scientists were able to use years of data, research and advances to fast-track these lifesaving vaccines.

“All science builds,” said James Hoffman, PharmD, chief patient safety officer. “The fact that we were able to make these vaccines available so quickly can be traced back to many different scientific advances.”

Knowledge of similar viruses

In some ways, researchers had a head start in the race to create effective vaccines for COVID-19.

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is a novel virus that causes Coronavirus disease 2019 (COVID-19). That means it wasn’t known or recorded before it emerged. But that doesn’t mean we’ve never encountered a virus like it before 2019.

An article published in Nature explains SARS-CoV-2 is like other viruses that have appeared in humans before. But none of them spread like SARS-CoV-2 has. SARS-CoV, more commonly known as severe acute respiratory syndrome (SARS), appeared between 2002 and 2004. MERS-CoV (Middle Eastern respiratory syndrome or MERS) first appeared in 2012.

These viruses are important because they’re similar in some ways to SARS-CoV-2. And researchers were already working on vaccines to treat them. According to Nature, there are two vaccines for SARS that were never offered to the public but were in Phase I clinical trials. 

Because of existing research about how to optimize vaccination against SARS and MERS, those working on COVID-19 vaccines already knew targeting the spike protein would be an effective way to help people make antibodies to protect against COVID-19. 

Understanding mRNA vaccines

Two of the three vaccines the FDA authorized for emergency use (Pfizer/BioNTech and Moderna) are mRNA vaccines. They help our bodies create an immune response to help stop an infection if we encounter the virus. 

Graphic explains mRNA COVID-19 vaccine

These vaccines are different than traditional vaccines because they don’t contain dead or attenuated viruses.

mRNA is fragile. So, the vaccines were formulated with lipid nanoparticles that protect the mRNA as it goes into the body. While “lipid nanoparticles” may sound exotic or even a bit scary, they are simply special harmless oils that encase the mRNA.

For decades a variety of lipid delivery systems have been used to safely deliver different medications within the body.  This experience gained over many years was critical to design the right delivery vehicle for the mRNA vaccines.   

It’s important to remember that mRNA vaccines don’t change our DNA. The vaccine doesn’t enter a cell’s nucleus. After injection, the cell’s processes the information and start building spike proteins. The mRNA from the vaccine is eventually destroyed by the cell, leaving no permanent trace. 

Over the years, many researchers have worked on developing mRNA vaccine technology. Researchers were exploring other uses for mRNA vaccines (combating diseases like rabies and Zika) as well as immunotherapy uses (fighting certain types of cancer) before COVID-19 appeared.

Thorough approval process

Emergency use authorization for COVID-19 vaccines moved quickly, thanks to the understood need to produce an effective vaccine against the virus as fast as possible. 

Communication, collaboration and resources were fundamental in this process.  The combined effort of many scientists working from existing technologies allowed the vaccines to be developed and tested in a shorter time period.  

But that doesn’t mean researchers and scientists weren’t putting the population’s safety first during the process. Getting a vaccine authorized was still a rigorous process. In fact, at one point more than 180 COVID-19 vaccines were in development. In the United States, only three vaccines are currently authorized by the FDA for emergency use. In late August 2021, the Pfizer/BioNTech vaccine received full FDA approval for use in people ages 16 and older.

“From a process standpoint, the failure of vaccine candidates illustrates the rigor that was involved in developing, testing and authorizing these vaccines,” Hoffman said. 

Work is continuing

While all data points to COVID-19 vaccines being both safe and effective, work on monitoring the vaccines continues. The Food and Drug Administration (FDA), CDC, researchers and developers are continuing to gather information about the safety and efficacy of COVID-19 vaccines. 

“The science is not stopping,” Hoffman said. “There are different layers of reviews and analysis happening. We are constantly learning about the vaccines. We continue to learn more about the vaccines every day.”

The benefit of COVID-19 vaccines outweighs the risks. And the data backs it up.


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