Our Immune System and COVID-19

Amid the growing panic of the novel COVID-19 pandemic, there have been many questions arising about our body’s built-in defense, our immune system: What exactly is our immune system? How does our immune system work? And most importantly: if our immune systems are our built-in defense, why isn’t it protecting us from COVID-19? What is our immune system and how does it work? Our immune system is our body’s defense system in order to fight illnesses like COVID-19. Our immune system is essentially made up of 3 parts, or lines of defense: our skin and external barriers, phagocytic cells and our inflammatory response, and antibodies. First Line of Defense Our first line of defense against invading bacteria and other infections is our skin and external barriers, such as mucus membranes. These barriers act as a gate that bars anything from our environment from entering our body. Our skin secretes oil which traps any bacteria that we may have touched or come into contact with and prevents it from entering our bodies. Since bacteria and other debris gets trapped on our skin oils, it's important to wash your hands and not touch our eyes, noses, or our mouths so we don’t introduce that bacteria directly into our bodies. Mucus membranes act in a similar way. The mucus membranes that line our mouths and noses, along with similar structures like our tear ducts for our eyes, trap and flush out any bacteria that has found its way there. Essentially any bacteria or debris that gets caught in these places are trapped in our mucus and get flushed out either by tears, or swallowing, or blowing our noses. However, since mucus traps debris and bacteria, it’s important to stay hydrated in order to help our bodies flush out the mucus as well as to produce more mucus. Second line of Defense However, if the invading pathogen gets past our first line of defense, it then has to face our second line of defense: phagocytic cells and internal defenses. Phagocytic cells are essentially “eating” cells. These cells include our white blood cells, which recognize pathogens and engulf or “eat” the invader. White blood cells recognize pathogens via the proteins on the invader’s cell surface. Each cell has its own surface proteins that act as a name tag that identifies it as our own body, or as an invader. Once the white blood cell recognizes this “name tag,” it undergoes a process called phagocytosis, which is when the white blood cell “eats” the invader, neutralizing it, and breaking it down. Our body also responds to the pathogen that has invaded with an inflammatory response. There are two types of inflammatory responses: local and systemic. Local inflammation happens in instances such as a splinter, where there is a cut in our skin, and therefore an opening for bacteria to enter. In this case, the swelling and redness stays in the area of the splinter, or locally, hence the name. The inflammation comes from our body flooding the area with blood, and therefore white blood cells, to fight the infection. Systemic inflammation is what happens when someone becomes infected with COVID-19. It is a whole-body, or whole system, response to the invading virus. What happens is our body releases a hormone that raises our body temperature. By doing this, microbial growth is inhibited, making it harder for bacteria and pathogens to survive and reproduce in our bodies. However, it comes at the risk of harming our own cells as well, since our own cells can’t survive outside of a certain range. Third line of Defense Our third line of defense works in tandem with our second line of defense and is our body developing cells that can defend against specific pathogens. These cells are our B and T cells, and they have “hands” that have a specific shape in order to bind to the specific proteins of the invading pathogen. Once our body pieces together the correct shape that fits the proteins of the invading pathogen, our body is able to fend off that specific pathogen. The best part is once our bodies have found a shape that works, it gets committed to our bodies memory via memory cells. If we get infected with the same pathogen again, our bodies will remember how to fight it, and thus strengthens our immune system. Why can’t our immune systems fight COVID-19? However, initially finding the right shape that fits the pathogen takes time, and in the case of COVID-19, many that are infected often don’t have that time. For example, people with compromised immune systems such as the elderly, babies, or those who have specific underlying health problems have weaker immune systems than healthy individuals. This puts them at a greater risk of infection, as well as compromises their ability to fight COVID-19 once they do get infected. For healthy individuals that become infected, it’s not that our immune systems are failing, but that COVID-19 is able to act faster. As our bodies scramble to make the right antigen, COVID-19 progressively advances within our bodies, causing pneumonia and difficulty breathing. Essentially, time is our biggest enemy. This race against time is why our best bet at fighting COVID-19 is by preventing infection altogether. Although scientists and doctors are working to find a treatment and a vaccine, those measures will also take time. So it’s important that we do all that we can to keep ourselves safe by washing our hands, maintaining a healthy lifestyle, and practicing social distancing. Sources: “Overview of the Immune System.” National Institute of Allergy and Infectious Diseases, U.S. Department of Health and Human Services, www.niaid.nih.gov/research/immune-system-overview. Harvard Health Publishing. “How to Boost Your Immune System.” Harvard Health, 2014, www.health.harvard.edu/staying-healthy/how-to-boost-your-immune-system. “How to Protect Yourself & Others.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 13 Apr. 2020, www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.