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- Hi, I'm Julie from the Exploratorium Welcome to Viral Questions, a video series where we answer your questions about COVID and vaccines. We finally have vaccines to help prevent COVID, but how do they work? These vaccines are an incredible feat of science but the real hero of this story is your immune system. I'm gonna bet you've seen this image from the CDC of the SARS-CoV-2 virus, the virus that causes COVID. We're gonna turn this into a simple cartoon that highlights the important parts for thinking about vaccines. The famous red bumps on the surface are the spike proteins. These are how the virus attaches to your cells in order to infect them. Since these are on the outside of the virus, they're the first thing your body might notice and identify as a foreign object. When you get infected with a virus, its main task is to make more copies of itself. It does this by getting into your cells and using them to make more viruses. Those viruses infect more cells, and it keeps going until your body can get rid of them all. Once your body recognizes that it's been invaded, your immune system gets to work fighting off the invaders. Your immune system is one of the most sophisticated systems in your body. I'm not gonna get into all of its details today. And it has a number of strategies to identify and fight off foreign invaders. What I wanna focus on starts with some of your immune cells noticing a foreign object and ends with some of them producing a special type of protein called an antibody, which are those Y-shaped things. These antibodies identify a specific foreign object that your cells have seen before and they're how we build lasting resistance to different viruses. The next time that foreign object comes into your body, it will be recognized and attacked. Now it takes some time for your immune system to do all of its work and fight off an invasion. When you feel sick, your body's undergoing a battle between your cells making more viruses and your immune system getting rid of all of them. When it succeeds in doing that, that's when you start to feel better. But being sick can be terrible, so wouldn't it be great if there was a way to shorten the time that it takes your immune system to respond? The way to do that is through vaccines, which give your immune system a preview of what the virus looks like before you ever actually get sick. The way most of the vaccines developed for COVID do this is to focus on that spike protein that covers the surface of the virus. If your cells can be trained to recognize spike proteins, they'll be prepared to attack a virus that has those proteins, if it ever gets in your body. You might think that one way to do this is to just inject spike proteins directly into your body. That might work, but it's really difficult to produce and deliver that. The current COVID vaccines actually take advantage of your own cells to make the spike proteins. Everything else about that cell is normal, it just has spike proteins on its surface. This difference is enough to alert your immune system and train it to fight anything with a spike protein. The critical thing is that it does this without introducing the whole coronavirus, just the surface protein, which can't hurt you on its own. So how do you get your cells to make spike proteins? You may have heard that the first two coronavirus vaccines approved in the US are mRNA vaccines. These are a new type of vaccine that holds great promise for many areas of medicine. So how does a mRNA vaccine get your cells to produce spike proteins? We'll explore that in our next episode of Viral Questions. See you then.