Hello, my name is Morgan Katz and I'm an Assistant Professor of Infectious Disease at Johns Hopkins University. Today I'm going to share with you a brief background on COVID-19 and how it poses a risk to assisted living communities. Let's briefly run through our learning objectives. First, we're going to describe the origins of the virus that causes COVID-19. We will then talk about how this virus can be transmitted between people, the timeline of infection, and finally, the specific signs and symptoms that have been associated with this disease, as well as risk factors for developing severe disease. The virus that causes COVID-19 is a coronavirus. Coronaviruses are a diverse group of viruses and you need powerful microscopes to see them. Corona means crown, it is named this because of how it looks under a microscope. I'm showing a picture of the virus on the slide, and as you can see, it looks like it has a crown on it. There are many different types of coronaviruses that infect a wide range of mammals and birds. Some even cause mild respiratory diseases like the common cold in people every year. These are not new coronaviruses, but SARS-CoV-2, the virus that causes COVID-19 is a new coronavirus, solet's talk about it. SARS-CoV-2 originated in bats, so that means bats carry this virus and are infected with this all the time. But this virus specifically developed the ability to jump between species and infect people. This is the third coronavirus since 2002 that has developed this same trick. The first was SARS-CoV-1, which emerged in China in 2002, the second is Middle Eastern respiratory syndrome coronavirus, or MERS, which originated in the Middle East. Finally in 2019, we saw the spread of the virus that causes COVID-19, SARS-CoV-2, which originated in Wuhan, China. As we discussed, SARS-CoV-2 is the virus that causes the illness we call COVID-19, which is short for coronavirus disease 2019. It's important to note here that not everyone who becomes infected with SARS-CoV-2 develop symptoms. In fact, some research in long-term care facilities has shown that over 50 percent of residents who are infected with SARS-CoV-2 may not report any symptoms. However, this does not mean that they are not able to transmit the virus, which is part of the reason it has been so hard to contain. For those that do get sick, we will discuss how this virus may be transmitted, how long someone may remain infectious, and some of the most common signs and symptoms. There has been a lot of research and some early confusion and unknowns about exactly how this virus is transmitted. We know now that the most common cause of transmission and highest risk of transmission is through respiratory droplets. That is being in close contact with an infected person for a prolonged period of time without protective equipment such as masks and eye protection. Respiratory droplets that include virus can reach the mouth, nose, or eyes of a susceptible person and can result in infection if protective equipment is not worn appropriately. The best way to protect yourself from respiratory droplet transmission is by wearing a mask and keeping a distance of at least six feet from others when possible. Fomite transmission is an indirect form of transmission where a susceptible person can touch a surface contaminated with the virus, then touch their own eyes, mouth, or nose. We are beginning to understand that this is probably not a driving force of transmission. The best way to protect yourself from fomite transmission is by washing your hands regularly and disinfecting surfaces with EPA approved cleaners. There is some emerging evidence pointing to the potential for airborne transmission. That is transmission of smaller particles in ranges greater than six feet. This is not the driving force of transmission of SARS-CoV-2, but maybe a contributing mode of transmission, particularly in crowded indoor spaces with poor ventilation. The best way to protect yourself from airborne transmission is to always wear a mask, avoid crowded indoor spaces and by increasing ventilation indoors by opening windows or using air filters. Finally, the virus has been cultured in both stool and urine. However, there has been no documented transmission from these sources to date. Let's move on to discuss the incubation period. That is the time between when someone is exposed to the virus and infected to when symptoms develop. The incubation period of SARS-CoV-2 can range from today's after exposure to 14 days. This is a long timespan, and the reason why quarantine after exposure lasts for a full 14 days. Most people will develop symptoms about five days after they are infected. Let's walk through a visual representation of the timeline of infection. Remember, the incubation period runs from 2-14 days after exposure. That is, a person may develop symptoms at anytime in this range after exposure, but around five days is the most common. Over 95 percent of people who develop signs and symptoms, do this by 14 days. Illness typically lasts about 10 days in mild cases, but can last two weeks or more in severe cases. A person is infectious, meaning they can spread the virus to others anywhere from two days prior to when their symptoms begin to 10 days after their symptoms develop and they start to improve. Patients who are immune-compromised may remain infectious for even longer. To recap, the SARS-CoV-2 infectious period is the time when someone is infected with this virus and can spread it to other people. For people with symptomatic disease, the infectious period begins two days prior to the onset of symptoms and lasts at least 10 days after the onset of these symptoms. This is important in the assisted living setting, because people may actually be infectious prior to developing any symptoms. It is why this virus has been so challenging to control, and to prevent entry into closed communities, because temperature and symptom screening alone may not prevent entry into the community. I will also note here that in severe cases or severely immune-compromised individuals, this infectious period may extend as long as 20 days. The tricky part here is that people who have no symptoms at all, can also be infectious. In these cases, it is often difficult to determine when they started to become infectious, because there's no onset of symptoms. In general, in these cases, we consider them infectious and recommend isolation for ten days after their positive test. Next, let's discuss some of the common signs and symptoms we see in people who do develop symptoms with COVID-19. First, let's briefly review the general definition between signs and symptoms. Signs are objective measurements which can be identified by a physical exam. These include a fever or elevated temperature, or fast breathing rate. Low oxygen saturation or hypoxia, may also be identified by a low pulse oximetry reading. Symptoms are subjective measurements, and refer to how the patients may feel. It is important to note here that signs and symptoms can vary widely even, and in some cases, especially in older individuals. Many people have no symptoms at all, some may have mild disease and some may develop severe disease that can lead to death. Common signs and symptoms in those who do develop symptoms include, fever, which is defined as a 100.4 degrees Fahrenheit or above, but with a caveat that older individuals often have lower baseline temperatures and do not exhibit temperature elevations like younger adults. I like to use a 99 degrees Fahrenheit cutoff for fever for older adults. Fatigue, chills, muscle pain, or cough. While many of the symptoms of COVID-19 are considered nonspecific, and can be seen with other viral illnesses, there are some symptoms that appear more specific for COVID-19. One these is an acute loss of taste or smell. Over a third of patients reported a loss of taste or smell at the onset of infection. This is something that appears to be relatively unique to this illness and is not common in other viral infections. One of the ways that COVID-19 causes severe disease and death, is through congestion in the lungs. Our lungs are how we get oxygen into our body, and if the lungs don't function properly, we can't get enough oxygen. I'm showing two pictures of CT scans, one on the left of a patient with healthy lungs, and one on the right of someone with lungs congested with infection with severe COVID-19. You see on the left side here that the healthy lungs have dark-field tissue, this shows you that the tissue is healthy. On the right here, you can see the same lung area that's pictured on the left, except you can see that it is white instead of dark. That shows that the tissue is severely damaged by the virus. This means that this person may have a very difficult time breathing, and getting enough oxygen into their body. This really gives you a good depiction of what the virus can do, and how it can cause severe disease and death. As we have discussed, this virus can cause a wide range of different symptoms. Unfortunately, there's no way to tell how infection can affect each person. That is why we must continue to remain vigilant, and continue safe practices to prevent its spread.
