[MUSIC PLAYING] SPEAKER: Now let's talk about how SARS-CoV-2 is transmitted between people. There are two main ways that SARS-CoV-2 is transmitted between people that you need to remember. So as you know, infected people have the virus in their respiratory tract, in their mouths, noses, and throats. And there are droplets that come out of our nose and mouth when we're talking, laughing, coughing, sneezing, singing even. Sometimes you can see them, but sometimes they're so small that you don't really notice them. But they're there anyway. If someone is infected with SARS-CoV-2, then those droplets that come out can have the virus in them. And then those droplets, if they land on someone else's face, in their mouth, nose, or eyes, can infect someone else. So if you are sitting close with someone, you're talking with them. You sneeze. You get a cough in the face. If you're sitting nearby someone, those droplets can travel far enough to infect you. The second way the virus is transmitted that you need to know about is through contact with surfaces that have viruses on them. So we just talked about how the virus is in respiratory droplets of people who are infected. So if those droplets get on surfaces, or they're on the infected person's hands and that person touches a surface like a table or a doorknob, they can leave the virus on that surface. And then the virus can survive or stay on those surfaces, and it contaminates the hands of other people. Now if you touch a surface that has the virus on it, and then your hands touch your mouth, nose, or eyes, the virus can infect you that way. That's why hand washing and cleaning are so important for preventing transmission, because many people can get infected through their hands. In hospitals, patients have procedures done that may increase transmission. But that's a specific setting, and we're really focused here in this lecture on transmission out in the communities, so outside of the hospital setting. So as you already know, people who are infected with this virus will have infectious virus in their respiratory droplets. When you sneeze, cough, talk, or sing, those viruses and those droplets can travel up to six feet, which is a pretty long way. And those viruses could land in eyes, noses, or mouths of other people and infect them that way. Or, as we already mentioned, they could land on surfaces. That's why mask use can be one way to reduce transmission. This is primarily to keep infectious droplets from contaminating the environment. So if someone who is infected is wearing a mask, then there are fewer infectious droplets that will come out from their mouth and nose. Wearing masks is a great way to prevent people from infecting others. Something to keep in mind is that SARS-CoV-2 is transmitted very efficiently. So this virus transmits between people in ways that make it very difficult to detect and stop. People are infectious before they have symptoms, so they may be infecting others and not even know it. Some people never develop symptoms, and so they could also infect other people without knowing that they, themselves, are infected. So it's important for us to test symptomatic people and identify who they've had contact with quickly to try to limit the spread. This is done through contact tracing, and you'll hear more about this. So knowing how the disease is transmitted, it makes sense that transmission is more likely to occur the closer the contact you have with someone else. So people who have physical contact with a patient or have close contact are more likely to be infected. By close contact, we mean people who are within six feet of the patient for 15 minutes or more. Now why six feet? Well, that's the distance that we know that those infectious respiratory droplets can travel. And 15 minutes means that you've been around them long enough so that you may have come into contact with some of those infectious droplets. So that's what we call a close contact. And close contacts may have never had actual physical contact with the patient, but they're close enough so that they could be at risk for transmission. People who share an environment with someone who's infected are at some risk for infection themselves. And an example of a shared environment is an office or even a restaurant, if you're close enough to the person. Sharing food and bathrooms is another example of a shared environment where infection could be transmitted. And sharing a bed is another way that transmission could occur. Again, because you're in close contact or physical contact with someone who has the disease. For all of these reasons, transmission is much more likely between people who live together, because they're often having physical contact as well as sharing spaces. There are some living conditions that dramatically increase the risk for transmission. Sometimes we call these congregate housing settings, and it means essentially when there are many people living in very close quarters. Prisons and jails are examples of congregate housing, as are group homes, dormitories as like at schools, or shelters. These places are all high risk for very quick spread of the infection, because people are living close together and sharing spaces. When we think about risk for transmission, nursing homes really represent a worst case scenario for COVID-19. This is because you have, of course, people living in close quarters together who may have frequent contact with each other. But they also represent a group of people who are at very high risk for severe disease because of older age, multiple underlying health conditions that put them at increased risk for severe disease. They may need multiple interventions, such as feeding and toileting, so they're having very close contact with caregivers. Staff are at increased risk because of this, because they're having such close contact with patients. And importantly, nursing homes aren't hospitals, so they're not well equipped to take care of people who develop severe infections from COVID-19. So nursing homes are a place where transmission can happen very quickly, and people will be at high risk for infection. And if they are infected, the health consequences are severe. So these really are worst case scenarios for outbreaks of COVID-19. [MUSIC PLAYING]
