>> So, everyone, I'm Abby Carlson. I'm an infectious diseases physician and a doctor here at the Centers for Disease Control and Prevention in Atlanta, Georgia. And today, we're going to talk about a topic that you hear about a lot, respiratory droplets and how they spread COVID-19. Okay, we know that we want to keep from getting infected with the virus, SARS CoV2, so that we don't get sick with the disease, COVID-19, but how does the virus get from one person to another? The answer is actually different for every virus, but for SARS CoV2, the main way that the virus seems to travel between people is through something called respiratory droplets, but what are those? In this case, droplets doesn't just mean a water that you can see, like big raindrops or splashes in the sink or a pool. These droplets we're talking about are actually really tiny, and where they come from might surprise you. You might think that when you breathe out, all that comes out is air, right? You don't see anything else. But in fact, our breath contains a lot of water, and usually, you can't see that water. But think about it for just a moment. When you go outside in cold weather and you breathe out, you see your breath, or if you breathe on a mirror, it fogs up, or this one actually happens to me all the time. When I'm in the hospital, I put on my mask, and my glasses start fogging up. What you're seeing in all these cases is not air. It's all the water in your breath. Those are your respiratory droplets. So, every time that we let out air when we breathe, whether we're talking or singing or just sitting here breathing, we also let out those little, tiny, respiratory droplets. I'll pause here for a moment and say that although all of these droplets are small, they aren't all the same size of small. Some you can actually see, like when you sneeze. Most of them, though, are sizes that we can't see, and different-sized droplets can travel different distances in the air. Some will go farther than others. The distance they travel also depends on other things like the air currents in the room or how strongly they were pushed out, like when you cough. We'll talk about these ideas more in another episode later on, because this difference in sizes is very important for certain things we do in infection control. For now, though, it's important to know that even though these droplets come in a lot of different sizes, they're all small enough and light enough that it another person is close by, and we aren't wearing our masks, say, we're eating at a table or we're with the patient who doesn't have a mask on either, then that person can breathe in the droplets that we've just breathed out. And when someone is infected with SARS CoV-2, those tiny respiratory droplets have virus particles inside of them. If you breathe in respiratory droplets, they're caring that virus that can then get onto your nose and into your throat and your lungs. It sounds really gross, I know, but that's what happens. And they can also land on your eyes. And when those droplets landed in all of those places, the virus lands on cells. Some cells, they can't get into. They just don't have the way in, but like many other respiratory viruses, SARS CoV-2 is able to get into a lot of cells in our nose, our throat, our eyes, and our lungs, and when that happens, virus can then hijack the cells. And that's how we get sick with COVID-19. We'll talk more about how, exactly, viruses hijack cells in another episode. So, be sure to stay tuned for that. Now if the goal of infection control is to keep people from getting sick, and we know that respiratory droplets are the main way SARS CoV-2 moves between people, then we know that the actions that we take for infection control and that we need in healthcare settings are things to keep people, ourselves and our patients, from breathing in each other's respiratory droplets. I know there are already a lot more questions about this topic. We've covered respiratory droplets very quickly today, and we'll talk more about them in future episodes, because there's a lot to cover. For the meantime, thank you all for joining us. As always, be sure to follow up on Facebook or Twitter and check us out on our website at CDC.gov/ProjectFirstLine. We'll see you back to the next episode.