 In the previous video on the coronavirus which I heavily recommend you check out, we took a look at the basics of what exactly the coronavirus is. But of course, many of you by now are asking another important question. In the unfortunate event where you do get corona, how does your immune system fight it off? Before we get started, I wanted to mention a quick clarification from the last video. The virus which is in the news right now is called the SARS-CoV-2 virus and the disease name is COVID-19. But at this point, given what the WHO and media keep calling it, it's alright if you called it the COVID-19 virus. Anyways, let's jump right into it. The coronavirus usually invades the respiratory system through the nose and then proceeds to cause respiratory illness. Symptoms may not show up for 3 to 13 days, but when they do it's usually in the form of fever, body aches, coughing, nasal congestion, runny nose, sore throat, and in severe cases, shortness of breath. The coronavirus can't replicate on its own and needs a host in order to do so, which is why it likes to infect us. Once inside the airway, the coronavirus will usually invade cells by attaching onto a protein receptor on top of the cell, which is usually the ACE2 receptor. Once the cell fuses with the virus, the virus then releases its genetic material, consisting of a single-stranded RNA molecule from its spherical body. The viral RNA is then translated inside the cell into the proteins needed to assemble more viruses, which are then released from the cell. In some coronaviruses, the viral RNA codes for a protein which can go to the surface of the host cell and essentially give the false impression to all neighboring cells that everything is all right, allowing the virus to spread without being detected by the immune system. But what happens in the typical scenario where your immune system does come to the rescue? Upon the infection of the epithelial cells in the airway, special cells called RDCs acquire a surface protein from the infected epithelial cells and proceed to the lymph nodes and present the protein to immune system cells called T cells. These T cells then go to the infected area and release molecules called cytokines, chemokines, and cytotoxic molecules, which kill infected cells, stop viral replication, and call for backup from other immune system cells to help fight the virus. Despite the very important role T cells play in fighting respiratory illnesses, as well as any illness in general, not much is known about their responses to corona infections. Although past studies have shown that in severe cases of SARS-CoV infections, T cell counts decreased. Causes of this could be the RDCs not properly traveling to the lymph nodes and activating the T cells, or the body releasing steroid hormones due to the stress it's going through which can result in the T cells killing themselves, as well as a multitude of other reasons which are far too complicated to go into for now. Most people infected manage to fight it off, but that doesn't mean this virus should be treated like it's simple cold. People have been hospitalized by this, and we already know by now that it can hinder or in some cases completely bypass your immune system, which can be fatal. Worst of all, we don't know what the long-term effects of this virus are, and some doctors suspect that COVID-19 could lead to permanent lung damage in the long run, even after recovery, although it's too early to know for sure. In the meantime, you as an individual have the power to stop this virus through social distancing. Now, we're not going to go too deep into the numbers or math, but just take a look at this diagram where the dots are people and the arrow is the virus being spread. Notice just how one person deciding to not make that unnecessary trip or quarantine him or herself after being diagnosed can mean the difference between good health and potential death for many others. Even if everything else in this video flew right over your head, it's important that you understand why social distancing is an absolute must. Even if you can fight the coronavirus, you may pass it on to someone with the compromised immune system, such as an elderly individual or someone undergoing chemotherapy or a patient with pre-existing respiratory conditions who can't. So please do the right thing and stay home if you're sick. Don't be a COVID-yit. In the meantime, be sure to stay tuned for more updates on the coronavirus as the situation unfolds. And no matter what, don't forget to stay tuned for more science videos.