Woman with a mask checking her phone
Woman with a mask checking her phone
Woman with a mask checking her phone

Coronavirus: COVID-19 Terms You Should Know

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In the last several months, you’ve probably had a crash course in understanding the basics of the novel coronavirus and COVID-19.

It’s likely some new words have probably found their way into your everyday vocabulary as more and more information emerges. Lisa Maragakis, an expert in infection prevention at Johns Hopkins, reviews some of the terms you might know, and some that might be new to you.

Aerosol: Solid particles or tiny droplets of liquid suspended in a gas or mist. In terms of infectious disease such as COVID-19, aerosol describes a cloud of infectious virus particles or droplets, emitted by an infected person, which lingers in the air.

Airborne transmission: Transmitted through the air, as in the case of a contagious virus. Some viruses can create tiny particles that, when released into the air from an infected person, can float in the air for hours and infect someone else who enters that area and inhales them. Airborne diseases are very contagious. Researchers are trying to find out if SARS-CoV-2, the coronavirus that causes COVID-19, can be spread in this way.

Antibodies: Proteins created and released by the body’s immune system to fight a specific disease. Antibody treatment is one method currently being explored by researchers looking for a treatment for the coronavirus.

Antibody test: A test to detect proteins that signal the person has been exposed to a particular germ. Sometimes — but not always — a positive antibody test can mean the person is immune to disease caused by that germ. Scientists are gathering data from antibody tests given to people who have recovered from COVID-19 to learn how the immune system fights off the illness.

ARDS: Acute respiratory distress syndrome, a type of lung failure seen in some instances of very severe COVID-19 disease.

Asymptomatic: Showing no symptoms. Up to half of people infected with the coronavirus have no COVID-19 symptoms. Some of these people might be “pre-symptomatic,” meaning that they don’t have symptoms now but might develop symptoms later. A person who is asymptomatic for COVID-19 may still show symptoms for other illnesses.

Coronavirus: A group of viruses that appear under the microscope to have a “crown” of protein spikes. There are hundreds of coronaviruses. Some are common and cause mild colds. Some affect only animals. Other types of coronaviruses cause serious respiratory diseases such as SARS and MERS. The coronavirus that causes COVID-19 is named SARS-CoV-2.

COVID-19: Coronavirus disease 2019. This disease is caused by SARS-CoV-2, a new coronavirus that emerged in China in December 2019. Severe COVID-19 can cause pneumonia, lung failure, kidney failure or death.

Droplet: A small drop of fluid. Droplets of mucus and saliva are expelled into the air when a person coughs or sneezes, talks, laughs or sings. Droplets containing the coronavirus can spread the infection through the air, especially among people close together indoors. In some cases, the droplets can land on surfaces. People touching that surface might get the virus on their hands and infect themselves by touching their face.

Epidemic: A sudden increase in the number of people catching a disease affecting a community such as a town or city.

Herd immunity: When enough people are immune to an infectious disease (either because they have had it and survived or because they’ve been vaccinated for it) that the disease can no longer spread easily from person to person within the community.  

Incubation period: The time between when a person is infected and when they show symptoms. The incubation period for COVID-19 is three to 14 days, with an average of five or six days. Although a newly infected person may not show symptoms during the incubation period, they can still transmit the coronavirus to others.

Intubation: This is a procedure where a breathing tube is placed down a patient’s throat into the trachea, or windpipe. The breathing tube is connected to a ventilator, which breathes for the patient, who is asleep under anesthesia. Treating COVID-19 might require a combination of a ventilator and intubation to help patients breathe and get enough oxygen.

MERS (or MERS-CoV): Middle East respiratory syndrome, a respiratory disease caused by a coronavirus that’s different from the one causing COVID-19. The first MERS outbreak happened in 2012. Because so many people who have MERS become severely ill, it is clear who is infected and easier to make sure those people are quarantined.

N95: A face covering respirator worn by medical professionals as they care for patients who have infectious disease. Although it may look like a face mask, because of its properties it is called a respirator.

Outbreak: An unusually high number of disease cases in a particular location, for instance, on a cruise ship or in a daycare center or hospital.

Pandemic: An infectious disease epidemic that spreads over several countries and continents, infecting large numbers of people.

PAPR: Powered air purifying respirator. This battery-operated device filters air and blows it through a hood that covers the head and face. Sometimes part of personal protective equipment (PPE, see below), the PAPR is worn by health providers to protect them from infectious diseases.

Physical distancing: The practice of staying at least 6 feet away from others to avoid catching a disease such as COVID-19. “Social distancing” is a term that was used earlier in the pandemic as many people stayed home to help prevent spread of the virus. Now as communities are reopening and people are in public more often, physical distancing is used to stress the importance of maintaining physical space when in public areas.

PPE: Personal protective equipment. This refers to the masks, gowns, goggles and other protective garments worn by health care professionals caring for patients with infectious diseases such as COVID-19.

PUI: Patient under investigation. These are people being tested for COVID-19 and who are showing signs and symptoms of the infection.

R0: (pronounced R-naught): This is a measure of how contagious a disease is, and represents the average number of people who will catch the disease from one infected person. COVID-19 has an estimated R0 of 2 to 2.5, meaning for every person who gets the illness, two or more additional people catch it from that person. In order for a pandemic to end, the R0 needs to stay less than 1.

SARS: Severe acute respiratory syndrome. This was the name given to a disease that appeared in February 2003 that caused pneumonia, lung failure and death. It was found to be caused by a type of coronavirus, but a different type than the one that’s causing the current pandemic.

SARS-CoV-2: The formal name of the coronavirus that causes COVID-19 and that is behind the current pandemic. “CoV” stands for coronavirus. The “2” means that this is the second coronavirus to cause SARS.

Social distancing: A term used to indicate the need to stay home and away from others as much as possible to help prevent spread of COVID-19. The practice of social distancing encourages use of things such as online video and phone communication instead of in-person contact. As communities are reopening, the term “physical distancing” is now being used to reinforce the need to stay at least 6 feet from others, as well as wearing face masks.

Ventilator: A ventilator is a machine that helps a person get more oxygen and breathe when they cannot breathe normally on their own. When a person has pneumonia from COVID-19, the air sacs in their lungs become inflamed and filled with fluid, preventing oxygen in the air they breathe from reaching their bloodstream. The ventilator can be used with a mask that forces oxygen-enriched gas into the person’s lungs. However, for many COVID-19 patients, a ventilator plus a procedure called intubation, or placing a tube into the airway, is necessary to assist with breathing.

At the start of 2020, you might not have known how to make or wear a face mask, why washing your hands for 20 seconds is important or how to participate in an online meeting. But you likely know those things now. Knowledge of these terms can help you make better sense of the large amounts of information you’re receiving each day as the COVID-19 pandemic evolves.

ABCs of COVID-19 from Johns Hopkins Medicine

Scientist carefully insets a pipette into a test tube.

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Updated July 31, 2020