People around the world have felt as if more than a year of their lives had been taken away due to the COVID-19 pandemic. How can they not? The pandemic has caused multiple businesses to close and has resulted in the loss of many lives. COVID-19 can be transmitted through the fecal-oral route or through respiratory droplets. Some people who were infected with the virus often compare it to the ordinary flu. However, vulnerable groups have experienced much more severe symptoms including organ dysfunction. Unfortunately, the death rates in Indonesia seem to rise due to the shorthanded number of medical practitioners and hospital facilities to treat those who are experiencing said symptoms.
Firstly, the common and mild symptoms of COVID-19 are flu symptoms, anosmia, and ageusia, most commonly experienced by teenagers and young adults. Influenza (flu) and COVID-19 seem to present similar symptoms and transmit through contact and droplets but are two different viruses. COVID-19 is proven to be more contagious and takes longer for symptoms to develop compared to the common flu. Furthermore, 55% of Covid-19 patients experience anosmia which is the transient inability to smell. However, it is important to understand how our sense of smell works. When an individual inspires air, it brings in chemicals and odorants into our nose that will be taken in by the olfactory epithelium with millions of sensory neurons, then to the olfactory bulb, and it will eventually send messages to the central nervous system. Within the olfactory epithelium, there are many supporting cells such as the microvillar cells, globular basal cells, and more that ensure homeostasis. When presented with the SARS-CoV-2 virus, it will bind to ACE-2 (angiotensin-converting enzyme 2) and TMPRSS2 (serine protease) will cut some of the protein that is found on the outside surface of the virus to allow the protein to activate and embed itself into the membrane. Once the DNA of the virus is replicated, it damages the ability of the supporting cells in the olfactory epithelium to maintain homeostasis. This causes the sensory neurons to lose their ability and fails to send information to the brain. Hence the loss of the sense of smell. Once the virus is gone, the supporting cells will regain their ability and return the sense of smell. On the other hand, ageusia is the loss of taste. The tongue consists of papillae that have sensitive microscopic hairs called microvilli that send messages to the brain for our taste bud. However, the recognition of flavor works together with the olfactory sensory neurons to be sent to the brain. Thus, when the olfactory sensory neurons are unable to fulfill their ability, the brain is unable to recognize the taste. 10% of people were still unable to taste and smell a month after being infected by COVID-19. Fortunately, mild symptoms will clear up in a week or two. Physicians recommend smelling strong fragranced items such as essential oils, coffee, or spices to help the body regain its senses.
Secondly, the heavier symptoms of COVID-19 are usually experienced by vulnerable groups and require medical care. The organ that is most affected by COVID-19 is the lungs since it is a respiratory disease. When the SARS-CoV-2 particle is inhaled, it will go to the alveoli, tiny air sacs in the lungs where gas exchange of O2 and CO2 occurs. There are three main types of cells which are type I pneumocytes to ensure gas exchange between the alveolus and the bloodstream, type II pneumocytes produce surfactants to prevent the walls of the alveoli from sticking to each other, and macrophages are immune cells that capture particles such as bacteria and viruses. The S protein from the virus will bind to type II pneumocytes through ACE-2 (angiotensin-converting enzyme 2) cells. This enzyme turns AT2 (angiotensin 2) to AT 1-7 (angiotensin 1-7) resulting in a decrease in blood pressure and has anti-inflammatory properties. Once the virus is taken into the cell, the RNA will be released into the cytoplasm of the type II pneumocytes allowing it to replicate with the help of ribosomes and take control of the body’s transcriptional machinery. From there, 67.7% of patients develop a dry cough and the virus is now transmissible through respiratory droplets. By then, the type II pneumocytes will be destroyed and released inflammatory mediators causing macrophages to release pro-inflammatory chemicals such as cytokines. Cytokines cause the endothelial cells of the capillary to undergo dilation and become more permeable. As a response to that, the plasma fluid leaks to the interstitial space and the alveoli. The excessive amount of fluid in the lungs hinders gas exchange and disrupts the ability of the surfactant leading to acute respiratory distress syndrome (ARDS). This condition is 30%-40% fatal where the patient would require a ventilator and oxygen tanks to treat shortness of breath to bring oxygen into the bloodstream. Most COVID-19 deaths are due to when the lungs are too flooded and hypoxia occurs (not enough oxygen reaching the tissues). Those who survive may suffer from long-term lung damage such as holes- giving a honeycomb effect. Then, the inflammation in the alveoli attracts white blood cells called neutrophils which release proteases in hopes of destroying the virus. However, healthy cells will also be destroyed causing pus and the thickening of the barrier, making it even harder for gas exchange to transpire. Other than that, cytokines will send signals to the hypothalamus through the bloodstream, a part of the brain that regulates temperature, causing the patient to suffer from a fever which is one of the most common COVID-19 symptoms.
The critical condition happens when the inflammatory chemicals can jump into the bloodstream and affect the rest of the body. Eventually, systemic inflammation causes septic syndrome. The capillaries throughout the body will increase in permeability causing a decrease in blood volume and the patient will become hypotensive. Eventually, a drastic decrease in perfusion or delivery of blood can result in multisystem organ failure (MSOF). For example, the kidney will lose its ability to remove waste. Subsequently, resulting in kidney damage due to the elevated amount of creatinine and blood urea nitrogen (BUN). A second example is when the liver will start to release inflammatory enzymes and acute phase reactant proteins, indicating organ failure.
COVID-19 symptoms differ depending on the immune system and medical history of the infected individual. Those who have a good immune system are more likely to experience mild symptoms such as coughing, runny nose, and the loss of the sense of taste (ageusia) and smell (anosmia) which do not require medical attention. Whereas those in vulnerable groups are more likely to suffer from acute respiratory distress syndrome, organ dysfunction, and post-covid conditions which require immediate medical attention. In conclusion, it is important for us to be responsible for our actions throughout the pandemic to prevent this community disease from continuously infecting others, especially vulnerable groups.
Works Cited
Matt. “COVID-19 and Loss of Smell Explained.” YouTube, 27 Aug. 2020, www.youtube.com/watch?v=h1kDzqpDlY0.
Matt. “COVID-19 | Pathophysiology.” YouTube, 28 Mar. 2020, www.youtube.com/watch?v=OW7UP_JllO8.
motivationaldoc. “Lost Your Sense of Taste? Ways to Get It Back | Dr Alan Mandell.” YouTube, 22 Dec. 2020, www.youtube.com/watch?v=YgfEhn075Bs.
Ninja Nerd. “COVID-19 | Coronavirus: Epidemiology, Pathophysiology, Diagnostics.” YouTube, 16 Mar. 2020, www.youtube.com/watch?v=PWzbArPgo-o.
Science Insider. “What Coronavirus Symptoms Look Like, Day by Day.” YouTube, 18 Mar. 2020, www.youtube.com/watch?v=OOJqHPfG7pA.
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