An mRNA vaccine sounds very science-y. And it is. It relies on known science to produce immunity without ever needing to inoculate the body with dead virus. Pretty nifty.

Though mRNA vaccines are new, they have been studied for decades. Basically, once we know some key information about a virus, we can use that intel to produce an immune response. Here’s how it works.

Instead of putting a weakened or inactivated virus into the body like the more “traditional” vaccines do, mRNA vaccines, such as the Pfizer and Moderna COVID-19 vaccines, send in a set of instructions (the mRNA) to create a protein that will trigger an immune response inside the body.

Specifically, for the mRNA COVID-19 vaccine, the mRNA, housed in a fat molecule to keep it all nice and cozy and protected as it gets transported, enters cells and says, “Here are instructions to make the ‘spike protein.’ Please read them carefully and follow all the steps.” The cells do what cells do: They read the mRNA like you would read a recipe and then out pops a spike protein, which is totally harmless.

After that, the cell breaks down the mRNA, like ripping paper instructions, and trashes it. The mRNA never gets into the nucleus, so there are no chances of it interfering with your DNA. Essentially, once the spike protein is made, the cells wipe their hands of the mRNA: thanks, bye!

The cells then put this spike protein on their surface, like a pirate flag, and the immune system says something like, “Oh heck no, techno! You don’t belong here.” And so begins the immune response. Antibodies are created.

These antibodies are basically troops trained and ready to recognize anything with these spike proteins, latch onto it, and flag it for destruction. Basically, should the virus dare enter the body, the antibodies are like, “Hey, it’s those spikey things! Does not belong. Must destroy!” The immune system listens and fights off the danger all while you, you vaccinated smarty pants you, sip your coffee, or take a warm bath, or run around the park, or [enter preferred leisure activity here] in peace.

In short, mRNA COVID-19 vaccines work by giving your cells step-by-step instructions on how to make copies of the harmless spike proteins so that if you get exposed to the real virus later, your body will recognize it and fight it off.

The benefit of mRNA vaccines, like all vaccines, is that you gain protection from the virus without ever getting sick. For the COVID-19 vaccine, it’s a free pass to safety from evil COVID-19.

Speaking of safety, for the record, mRNA vaccines are held to the same rigorous safety and effectiveness standards as all other types of vaccines in the US. Just because it was developed quicker than other vaccines, doesn’t mean corners were cut. Once scientists knew the genetic code for those spike proteins, they could begin designing and testing mRNA technology that tells the body, “Hey, watch out for this, and when you see it, take care of it, and by that I mean end it.”

The science behind the mRNA vaccine is built on a solid foundation of earlier scientific insights, such as understanding how the structure of mRNA works to produce a protein, inventing the technology to get the genetic sequence of a virus and build an mRNA that creates a specific protein, and overcoming the challenges of making sure the mRNA that is injected into the arm muscle finds its way to immune cells. mRNA vaccines are new, but the science is not.

And the effectiveness? Well, good news there. The simple version: it works. A recently published real-world study by the CDC confirmed protective benefits of mRNA COVID-19 vaccines. Two weeks after the second dose (the recommended number of doses), risk of infection is reduced by 90%. That’s an A for mRNA vaccines.

If you’re interested in learning more about the COVID-19 vaccines, the CDC is a great resource with key things to know. Be wary of what you hear in popular media outlets unless it comes from a reliable source, such as your county or state health department, the CDC, or the World Health Organization (WHO). It’s very important that we only spread good, valid information. And in that vein, please feel free to share this evidence-based article with your circles.

If you’re more of a visual person, here’s a handy infographic from the CDC on how mRNA vaccines work. It can also be found in Spanish here.