For a while the COVID-19 infection rate looked to be stabilizing in the U.S., and the country almost dared to relax a little. Then in late June it went up again—way, way up. In half a year, the novel coronavirus, only 80 billionths of a meter wide, has brought nations to their knees, stalled economies, and claimed over half a million lives as scientists and public health officials around the world grapple to understand this destroyer.
What makes SARS-CoV-2 (the virus that causes COVID-19) so formidable and so unlike any virus that has been studied in the past? Here are a few things scientists know about the novel coronavirus:
It’s extremely contagious. Doctors agree that SARS-CoV-2 is among the most contagious viruses they’ve seen. Virus particles are found at very high levels in the nose and mouth, so it is easier for them to escape (called “shedding”). In many other viral respiratory ailments—like SARS CoV, responsible for the 2003 SARS epidemic—the virus settles deep in the lungs and so does not shed as easily. On July 9, the World Health Organization conceded that virus particles can float in the air for hours in indoor spaces, where they can infect others and possibly spark super-spreader events. Even talking and singing can send virus particles aloft.
The virus can be spread by someone without symptoms. Unlike people with the flu, who usually don’t transmit the virus until they show symptoms, those infected with SARS-CoV-2 can transmit virus particles at a high rate even when they aren’t sick. Some studies report that 8 out of 10 individuals who test positive for SARS-CoV-2 have never had symptoms. Although some of these people will fall ill within a couple weeks, approximately 40% of those who test positive never develop symptoms. The CDC estimates that people without symptoms are 75% as contagious as those with symptoms.
It wreaks havoc throughout the body. “I’ve never seen anything closely resemble the virus in the spectrum of what it can do,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, in a June 24 interview. Although the virus is named “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),” the disease affects far more than the respiratory system. It can also harm the heart, blood vessels, eyes, skin, liver, kidneys, and gastrointestinal system. Symptoms range from those we first heard about—fever, cough, shortness of breath, and muscle aches—to nausea, vomiting, and diarrhea; painful, itchy red or purple lesions on the toes and hands known as “COVID toes”; a loss of smell and taste, which may persist for months; and more.
It can damage the nervous system. Researchers at the Northwestern University Feinberg School of Medicine found that approximately half of hospitalized COVID-19 patients have neurological symptoms, which may show up before or instead of other signs of the disease. Neurological complications include brain inflammation and swelling, delirium and psychosis, nerve damage, seizures, and strokes. COVID-19 patients have reported confusion, lack of coordination, bizarre hallucinations, blanking out on simple words, forgetting how to spell, and an inability to follow basic conversations or solve simple problems—even months after coming down with the disease.
It doesn’t endanger only the aged and infirm. Toward the beginning of the pandemic, COVID-19 was thought to pose a real threat only to the elderly and those with underlying health conditions. But when COVID patients in their 30s and 40s started having strokes and very young patients died of an illness resembling Kawasaki disease, which causes inflammation of blood vessels throughout the body, the world realized that the novel coronavirus posed novel threats. By the end of June, over 40% of hospitalized COVID-19 patients were in the 18-49 age range, up from 25% in March and April.
Bald men are at higher risk. Men are at greater risk of severe illness and death from COVID-19 than women, and bald men are at a particularly high risk. In Spanish hospitals, 79% of the male COVID-19 patients in one study and 71% in another were bald. Dr. Carlos Wambier of Brown University, lead investigator of a study on baldness and COVID-19, concluded that male sex hormones not only play a role in hair loss but are also “the gateway for the virus to enter our cells” and “a perfect predictor of severity” of COVID-19. On a positive note, prostate cancer patients treated with drugs to reduce testosterone levels were only one fourth as likely to contract COVID-19 as men undergoing other treatments, suggesting that hormone therapy may be an effective treatment for the virus.
Blood type plays a role. Preliminary data from a study of Italian and Spanish COVID-19 patients with severe respiratory disease suggest that people with Type A blood are at higher risk for the disease compared with other blood types, whereas those with Type O blood have a lower risk.
The virus is a monster at the molecular level. “At the molecular level, it’s something we’ve never seen before,” said Nevan J. Krogan, a molecular biologist at the University of California, San Francisco. He explained, “This gets into every major biological process in our cells.” Proteins on the cell membrane are often used for cell signaling, allowing cells to detect and respond to outside threats, but SARS-CoV-2 disrupts a cell’s communication system. Recent closeup images of SARS-CoV-2 in action, published in the journal Cell, show that the virus forms tentacles that branch out into neighboring cells, disrupting vital communications within and between cells. “[T]he virus is able to rewire all of the signals going on inside the cell. That’s really remarkable and it’s something that occurs very rapidly,” Andrew Mehle of the University of Wisconsin-Madison told the Milwaukee Journal Sentinel. (Read more about how cells communicate in our module Membranes 1: An Introduction to Biological Membranes.)
The virus is different now than when it was first detected. Viruses frequently undergo genetic mutations, and the SARS-CoV-2 virus has mutated into a version estimated to be 10 times more infectious than the one first detected in humans. (Read our module David Ho: HIV Researcher to learn how rapid genetic mutations helped HIV, the virus that causes AIDS, survive.) In a July 18 pre-publication paper, researchers from the University of California, Berkeley, stated that some people can be infected with two different strains of the virus at once, potentially triggering a dangerous immune response.
After untold hours devoted to studying the novel coronavirus and looking for ways to combat it, scientists agree on one thing:
We still don’t know much. “It really is very complicated, so we’re just at almost the beginning of really understanding,” Dr. Fauci acknowledged at a June 9 digital health-care conference. But there are new discoveries all the time as scientists work to develop a full picture of the novel coronavirus—its mechanism of infection, how it wars with the body, and how to treat it. Currently there are at least 95 vaccines in development, with some showing great promise. And the more scientists understand, the closer we will come to seeing an end to the pandemic.
Keep up with the latest COVID-19 statistics at CDC’s COVIDView: A Weekly Surveillance Summary of U.S. COVID-19 Activity.
Read personal accounts of post-COVID-10 brain problems in “Coronavirus survivors share their experiences with delirium, brain fog, and memory issues” in Business Insider, July 7, 2020.
Written by Bonnie Denmark
Bonnie Denmark holds an MA in linguistics and teacher certification in English, ESL, and Spanish. She has devoted her professional life to educational and accessibility issues as a computational linguist, multimedia curriculum developer, educator, and writer. She has also worked nationally and internationally as a language instructor, educational technology consultant, and teacher trainer. Bonnie joined the Visionlearning team as a literacy specialist in 2011, assisting the project by developing comprehension aids for science modules and creating other STEM learning materials.