What to Know About COVID-19 RNA Vaccines

Angela Cabotaje Fact Checked
gloved hand holding COVID vaccine vial
© Addictive Creatives / Stocksy United

Good news is finally here: The first vaccines for COVID-19 have been approved for emergency use in the United States.

While initial doses are being prioritized for front-line healthcare workers and those living in long-term care facilities — meaning most of us will have to wait several months for our turn — it’s still a light at the end of the pandemic tunnel.

Some more good news? These COVID-19 vaccines also represent a breakthrough in how we’ll fight future diseases.

Dr. Deborah Fuller, a vaccinologist and microbiology professor at the University of Washington School of Medicine, explains what makes these COVID-19 vaccines notable, what to expect when you get yours and where vaccine technology is headed in the decades to come.

What are the different types of vaccines?

Vaccines are a powerful tool that doctors use to help prevent you from getting sick with a variety of diseases. (And, just for the record, there’s no evidence that vaccines are unsafe or can cause autism.)

While you might think of all vaccines in the same way — a shot you get at a clinic, pharmacy or doctor’s office — there are differences in how they’re made and how they work.

Most of today’s mainstream vaccines fall into one of three categories.

Inactivated vaccines

These vaccines use a “dead” form of the pathogen — aka the virus or bacteria that causes a disease — to help your body recognize the germ and build up appropriate defenses. Because the pathogen is inactive, it can’t infect you and you don’t get sick.

“The virus is killed using chemicals or heat, and then the inactive pathogen is injected,” Fuller explains. “Your body then recognizes the antigens, or foreign substance, on the pathogen and stimulates an immune response.”

The flu shot is a common example of this type of vaccine.

Live attenuated vaccines

This type of vaccine again uses the pathogen, but with mutations purposefully inserted into its genetic code to weaken it so it can’t cause disease.

“This way, the pathogen can only replicate once or twice so you don’t get sick, but it makes your body think you’re infected and you launch an immune response,” Fuller says. “That later protects you from the real deal.”

Most of the current vaccines used today fall into this category, including the one for measles.

Recombinant protein vaccines

Rather than using a weakened or inactivated form of the pathogen, genetic code and all, these vaccines simply use a structural protein found on the outside of a virus that is used by the virus to infect your cells.

Think of the pathogen like a thief with a crowbar. In order to get into and infect your cells, the virus needs to attach to your cells — or, in other words, use a crowbar — to get inside.

In the case of recombinant protein vaccines, researchers identify the protein “crowbar” that a germ uses — for example, the spikes on the outside of a coronavirus — and then find the viral gene responsible for producing it. They then give that gene to cells in a lab, which produce the protein in large quantities.

“Then we purify that protein and inject it into people to stimulate the antibody response,” Fuller says.

Two common examples of this vaccine are the ones for hepatitis B and HPV, which can cause cervical cancer.

What to know about RNA vaccines

So where do the COVID-19 vaccines fall in all this?

They actually represent a different category of vaccines called nucleic acid vaccines, which include messenger RNA vaccines (mRNA or RNA vaccines) as well as DNA vaccines. Both Pfizer’s and Moderna’s approved COVID-19 vaccines are RNA vaccines.

“They’re similar to recombinant protein vaccines, but rather than taking that genetic code and using cells to make that protein in the lab, you take the genetic code and you put it right into people,” Fuller explains. “Your own cells then make the protein, and you essentially have your own body make the vaccine.”

If this seems like something straight out of a sci-fi movie, well, that’s understandable. The COVID-19 vaccines are, after all, the first time most of us have even heard about RNA vaccines — but they’ve actually been around for decades.

Fuller, who has been working on RNA and DNA vaccines since the late 1980s, says one of the key innovations allowing these types of vaccines to succeed for COVID-19 focuses on getting the RNA into our cells.

If RNA were injected into your arm by itself, it would simply float around outside of the cells and quickly become degraded. With RNA vaccines, however, researchers figured out how to encapsulate the RNA into lipid nanoparticles, a biomaterial that not only protects the RNA from degradation but also helps the RNA get into your cells by fusing with the cell’s membrane.

The only catch is that certain formulas of lipid nanoparticles aren’t stable at room temperature and need to be kept very cold, which is why Pfizer’s vaccine needs to be stored at minus 70 degrees Celsius and Moderna’s at minus 20 degrees Celsius.

Why RNA vaccines worked for COVID-19

Although traditional vaccines are more mainstream than RNA vaccines, there’s one reason why RNA vaccines crossed the COVID-19 finish line first: They’re much quicker to produce.

“RNA vaccines are the perfect rapid-response vaccine to pandemics because, unlike traditional vaccines, all you need is the genetic code,” Fuller notes. “The code for SARS-CoV-2 was revealed in early January, and it only took a few days to generate a candidate RNA vaccine that could be tested and prepared for clinical trials.”

A traditional vaccine, on the other hand, would take months to produce in the lab before it was ready for any sort of testing.

It’s this quick-turn adaptability of RNA vaccines that Fuller says can change modern medicine.

In her lab, for example, they’re currently working on a second-generation COVID-19 vaccine candidate. Their version uses a slightly different lipid nanoparticle that’s more stable at room temperature and can be produced separately from the RNA. This allows for faster manufacturing and easier storage (no ultracold freezers required) of the RNA and lipid nanoparticle, which can then be mixed right before use.

“RNA vaccines are going to be here to stay, and they’re going to be ready to pivot even faster to respond to future emerging pandemics,” Fuller says. “It’s really, in my mind, a revolution in vaccinology that allows us to continue improving and moving forward.”

What to know about COVID-19 vaccines

While Fuller and other researchers consider RNA vaccines a revolutionary step forward in modern medicine, that doesn’t mean they’re experimental or untested by any means.

“RNA vaccines have a pretty darn good safety profile,” Fuller says. “The COVID-19 vaccines that have been approved have been through phase 3 clinical trials, and that is where safety is truly evaluated.”

As with any vaccine, some people may experience moderate to minor side effects while others experience none at all. The most common side effects include soreness or inflammation where you receive the shot, as well as a mild headache, fever or muscle aches.

It’s also important to note that both of the approved COVID-19 RNA vaccines for emergency use are given in two doses. And, yes, you really do need both shots for full effectiveness.

“The first dose is to prime your immune system,” Fuller explains. “You produce memory cells to remember the antigen and you also produce some antibodies, but the level is usually below the threshold to provide you protection.”

It takes around three to four weeks for your body to generate enough memory cells. That’s why Pfizer’s vaccine doses are given 21 days apart, while Moderna’s are given 28 days apart.

By the time you receive that second dose, your body is prepared enough to expand those memory cells, which create a strong and more lasting immune response.

Although experts don’t yet know if you’ll need to get the COVID-19 vaccine every year, like you do with the flu shot, Fuller says the current approved vaccines are very good.

Just how well do these COVID-19 vaccines work? Both boasted around 95% efficacy in clinical trials, which Fuller notes is as good as any vaccine currently in use.

The bottom line

Receiving the COVID-19 vaccine is a major step forward, but it’s not the only thing you can do to help end the pandemic.

Most of the people who get the COVID-19 vaccine will be completely protected from getting ill with the disease, but since they can still get infected and carry the virus for a short time, they may still be able to pass the virus on to others.

In other words, don’t burn your face mask just yet.

Until enough people get the vaccine — and again, that can be several months still — we all need to continue wearing our masks and keeping our distance from others.

That said, the end is in sight.

“We encourage people to continue wearing masks for the time being and to get vaccinated when it’s their turn,” Fuller says. “For a little bit of discomfort, we can all end this long-term pain.”

The info in this article is accurate as of the publishing date. While Right as Rain strives to keep our stories as current as possible, the COVID-19 pandemic continues to evolve. It’s possible some things have changed since publication. We encourage you to stay informed by checking out your local health department resources, like Public Health Seattle King County or Washington State Department of Health.