SARS-CoV-2

In December 2019, Wuhan, a city in the Humbai province of China, became ground zero for what has since become a worldwide pandemic marked by the alarming spread and catastrophic health effects of the novel coronavirus. Doctors in Wuhan reportedly first detected the existence of the virus when they noticed several unusual cases of pneumonia in local hospitals. These patients presented with clinical symptoms of dry cough, dyspnea, high fever, difficulty breathing, and bilateral lung infiltrates on the CT scan imaging, among others. The local doctors did not appreciate the dangers at first. They thought that new strains of the flu were developing and that they would soon be eradicated, as had been done with past strains as they arose. 

Fast forward six months: What was believed to be a conventional flu confined to Wuhan, China, has made its way to 214 countries and territories, infecting nearly 8 million people and killing more than 433,000 as of June 14, 2020. The disease caused by the virus is known today as COVID-19, shorthand for Coronavirus-19. In hopes of understanding and learning more about this disease, including how to better protect ourselves and our loved ones from getting infected, how to develop appropriate habits to ward off infection, what to do when symptoms are felt, and what to expect in the future, I have decided to write about SARS-CoV-2, the virus the causes COVID-19. 

Before it was named SARS-CoV-2 – short for Severe Acute Respiratory Syndrome Coronavirus-2 – the virus that causes COVID-19 was given the temporary moniker “2019- nCoV” based on inferences that the virus first came into being in 2019. Once scientists had a fuller understanding of the viral genotype, the virus’ name was formally changed at the end of January 2020 to SARS-CoV-2. This was after the Coronavirus Study Group (CSG) of the International Committee on Taxonomy of Viruses concluded that the virus that causes COVID- 19 is a variant of the coronavirus that caused an outbreak of Severe Acute Respiratory Syndrome (SARS) in 2002-03 in Guangdong, a province in southern China. 

In general, coronaviruses are a large group of viruses that cause diseases in animals and humans. They belong to the family of enveloped viruses known as Coronaviridae, a viral family characterized by enveloped, positive-sense single stranded RNA that infects both animals and humans. This virus family is said to be zoonotic, meaning that the viruses often circulate among animals before evolving and then species-jumping into humans. In the specific case of SARS- CoV-2, the virus is known to have come originally from bats before evolving to infect pangolins and ultimately jumping from pangolins to humans. 

The Centers for Disease Control (CDC), the United States’ leading public health authority, reports that SARS-Cov-2 is spread mainly through respiratory droplets. For example, when an infected person coughs or sneezes, the virus travels though the upper respiratory airways into nasal or oral cavities, where it is then expelled through the droplets. Even if it does not immediately enter another human being, the virus can live on surfaces for anywhere from several hours to several days, depending on the surface. If anyone touches an infected surface and then touches his or her face, it is likely that the mucous membranes in the eyes, mouth, or nose will be infected with the virus as well, entering the upper airways and possibly giving rise to a range of symptoms described below. 

The World Health Organization reports that the incubation period in humans – the time between exposure to the virus and the onset of symptoms – is usually between two and 14 days in most cases, with a median incubation period of about five or six days. Certain factors such as a person’s age and underlying health conditions, if any, can lengthen or shorten the incubation period and mitigate or aggravate the symptoms. Infected people who are young and healthy are more likely to develop mild symptoms or no symptoms at all, while older adults with pre- existing conditions such as diabetes and heart disease are at greater risk of suffering more-severe symptoms, which can include high fever, severe cough, shortness of breath, persistent chest pain, and possibly even respiratory failure. Those who suffer mild symptoms generally improve after a couple of weeks of rest, nourishment, proper hygiene, and isolation. Those who develop more- severe symptoms can end up being hospitalized for weeks, being placed on ventilators, and even losing their lives. 

One of the most common complications observed in COVID-19 fatalities is ARDS, which stands for Acute Respiratory Distress Syndrome. With ARDS, fluid leaks into the lungs and severely damages them. The accumulation of the fluid impairs the lungs’ functions and reduces the supply of oxygen to the bloodstream. This eventually leads to hypoxia and death. Pneumonia, another common complication from COVID-19, develops when the air sacs in the lungs become inflamed, making breathing more difficult. Pneumonia fills the lungs with fluid or pus, depriving the bloodstream of essential oxygen. Scientists who have studied images of the lungs of severely ill COVID-19 patients have found that their lungs contained unnatural levels of fluid, pus, and cell debris. The symptoms of pneumonia can range from mild to severe fever, cough, headache, chills and difficulty breathing. 

In addition to the most common symptoms and complications, it has been found in a smaller number of cases that COVID-19 can affect both brain and gastrointestinal (GI) functions, even in the absence of respiratory symptoms. COVID-19 patients have displayed such neurological symptoms as loss of smell and taste, muscle weakness, tingling or numbness in the hands and feet, dizziness, confusion, delirium, seizures, and strokes. GI symptoms have included loss of appetite, nausea, vomiting, diarrhea, and abdominal pain or discomfort. These symptoms sometimes manifest themselves before – or, as noted above, even in the absence of – the more- common symptoms of fever, body aches, and cough. Studies have also found evidence that COVID-19 can cause lasting damage to the heart, lungs, kidneys, and liver, and lead to the formation of abnormal blood clots that can cause internal bleeding and/or organ failure. 

A particularly dangerous complication recently noticed in especially young children, usually 5 years of age or less, is multisystem inflammatory syndrome in children (MIS-C), sometimes referred to as “Kawasaki disease.” MIS-C can cause different body parts to become inflamed, including the heart, lungs, kidneys, brain, skin, eyes, and gastrointestinal organs. It is also characterized by severe fever, and can cause unusually red eyes, skin rashes, and a swollen tongue and feet. The CDC reports that many children diagnosed with MIS-C have had the novel coronavirus or been in the presence of someone who had COVID-19. 

As the worldwide death toll from COVID-19 continues to mount at the rate of more than 4,000 a day – far less than the peak of more than 10,000 a day in mid-April 2020, but still a breathtaking number – researchers on several continents have been working at a frenzied pace on more than 160 vaccines and a number of treatments against the coronavirus. There is, as of yet, no vaccine for coronavirus. Nevertheless, governments across the globe have streamlined their usual vaccine approval processes to speed up the clinical trials, licensing, inspections, and other requirements that drug manufacturers normally must navigate for years before they can bring a vaccine to market. Some companies have predicted that a vaccine may be developed by late 2020, but many experts are skeptical of that timetable. Among the challenges are developing a vaccine that is proven to be safe, long-lasting, and effective in people over 50, who usually do not respond to vaccines as well as younger people. And even if a vaccine is proven effective, countries still face the daunting challenge of producing enough doses to reach their entire populations. 

Meanwhile, there are still no treatments proven to be effective against COVID-19. With the most promising drugs still in the trial-and-error stage, desperate doctors are increasingly administering unproven medications to their sickest COVID-19 patients in hopes of giving them a chance at survival, however remote. Two of the most commonly prescribed drugs have been remdesivir, an unapproved drug originally developed to combat Ebola, and hydroxychloroquine, a drug occasionally (and controversially) touted by President Trump that has been approved to treat malaria and certain autoimmune disorders such as rheumatoid arthritis, but not COVID-19. By prescribing off-label uses for these drugs to treat COVID-19, doctors are resorting to whatever temporary measures they can while they await the development of evidence-based therapies and, most of all, a vaccine. 

According to data compiled from more than 6,000 front-line physicians in more than 30 countries by the health care data company Sermo, 55% use hydroxychloroquine, 21% use remdesivir, and 17% use plasma to treat their COVID-19 patients. Although none of these has been definitively proven to work against COVID-19, what is known is how they work in the body. Remdesivir, for example, essentially tricks the virus into grabbing remdesivir molecules rather than the fragments of RNA that it usually strings together to infect new cells and proliferate quickly in the body. When the enzyme used by the virus to create new RNA strands – known as polymerase – picks up a remdesivir molecule instead of an RNA fragment, the remdesivir molecule jams up the RNA assembly line and slows or even stops the replication of the virus. “Convalescent plasma,” in contrast,refers to the process of extracting immune cells from the blood of people who have recovered from COVID-19 and infusing them into people who are infected, creating a passive immunity in the latter group that may help them at least minimize some of the disease’s more-severe symptoms. 

The usual process for approving new therapies is often a long and arduous one involving frequent and costly failures with no guarantees of success. But with the spread of the disease outpacing the development of therapies to combat it, governments have been giving lightning- speed approvals to the use of unproven drugs to treat the sickest of patients. For example, although remdesivir has not been approved to treat any disease, the U.S. Food and Drug Administration has given special permission to doctors to treat their sickest COVID-19 patients with the drug. 

While a few biomedical companies such as Oxford’s AstraZeneca and Massachusetts’ Moderna have expressed optimism that a vaccine could be available by the end of 2020, many scientists remain skeptical. For now, the best way to keep safe from the disease is to avoid crowded spaces, practice social distancing, wear a mask when in the presence of others, wash hands frequently, and make a conscious effort to avoid touching one’s face. Until the urgent efforts in laboratories around the world to develop new treatments and vaccines begin to bear fruit, that’s the best advice science has to offer.