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.
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.
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.