ALBANY, N.Y. (NEWS10) — The relative quickness of their development, manufacture, and distribution has some people worried about the safety of COVID-19 vaccines. That and reported cases of severe side effects may make people reluctant to get vaccinated.

It’s also the first time a vaccine has been used to vaccinate millions in the U.S. and billions worldwide using messenger RNA (ribonucleic acid).

“There is not as much (ingredients) in these as traditional vaccines. That doesn’t mean we shouldn’t be concerned with safety but there is less to be concerned about, per se,” said Associate Professor of Microbiology at Albany College of Pharmacy and Health Sciences (ACPHS), Dr. Eric Yager.

To understand how mRNA vaccines work, it’s important to understand why they work. Because they teach the body to recognize and fight a particular virus or disease. A response, whether it be injection site reaction, the most commonly reported side effect for the Moderna and Pfizer COVID-19 vaccines, is a sign the body is producing an immune response to it, Dr. Yager said.

The mRNA present in the vaccines, provokes an immune system response. By teaching the body how to fight COVID-19, the vaccines provide protection against future infection.

A body’s response to COVID-19, whether through infection or vaccine is dependent on the individual. Just as responses vary in people who have been sick with COVID-19, it’s the same with the vaccination. Genetically, some people are more prone to have an allergic reaction, said Dr. Yager, who is also a faculty member of ACPHS’s Center for Biopharmaceutical Education and Training.

Moderna (mRNA-1273)

Pfizer-BioNTech (BNT162b2)

What’s the difference?



The Moderna and Pfizer COVID-19 vaccines contain four parts, the messenger RNA (the major component), lipids (fat droplets), salts, and sugars. Messenger RNA is the “blueprint that’s going to produce the viral protein that’s going to teach our body how to respond to the actual virus,” said Dr. Yager.

Messenger RNA is already present in the body. Scientists have been studying the use of mRNA for vaccines between 20-30 years but this is the first time it’s been able to be used in the creation of one, said Dr. Yager. Scientists isolated the COVID-19 spike protein (mRNA) so they could then synthesize it.

On its own mRNA is ineffectual. It breaks down easily and needs a component to keep it safe and allows it to bind to cells, something it also can’t do on its own. That’s why the vaccines contain a lipid (fat droplets), which protects and helps it stick to cells.

WATCH: Dr. Eric Yager further explains the ingredients in Pfizer’s and Moderna’s mRNA COVID-19 vaccines

All in all, the number of people who have experienced serious side effects from either vaccine remains low. The Moderna vaccine was looked at by the Centers for Disease Control and Prevention (CDC) after a string of serious adverse reactions, including anaphylaxis, were reported.

Out of ten cases of anaphylaxis, nine had experienced a prior allergic reaction to a vaccine, the CDC concluded. They also concluded that 2.5 people per million vaccinated had anaphylactic reactions. This was based on the more than four million people to have received Moderna’s COVID-19 vaccine and reported in the CDC’s Morbidity and Mortality Weekly Report released January 22, 2021.

Serious adverse reactions were reported in up to 4.8% in Pfizer’s clinical trial after the second dose and were more likely to occur in participants over the age of 55. Serious adverse reactions were reported in between .2-9.7% in Moderna’s clinical trial after the second dose and were more likely in participants over the age of 65.