COVID-19 Glossary of Terms

[Sources: Centers for Disease Control and Prevention (CDC), Johns-Hopkins University, and the North Carolina Department of Health and Human Services (NCDHHS)] 

The coronavirus, along with the enhanced policies and procedures in place to mitigate risk for infection, has introduced a new vocabulary to many people. Below are some terms you may encounter as you’re reading, watching, and discussing the COVID-19 pandemic.  

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. 

Antibody test 

After a person is infected, he or she typically develops antibodies. Antibodies help the body fight infection and, in many cases, develop immunity. Antibodies are found in the bloodstream and in body secretions, such as saliva. The antibodies that are most important in SARS-CoV-2 are called IgG antibodies. IgG develops 10–14 days after a person is infected. Antibody tests of the blood (and in some cases, saliva) can detect whether the antibody is present or not. A positive antibody test is evidence that the person had SARS-CoV-2 infection. At the current time, we don’t know whether this means whether the person is immune. In other words, we don’t know whether the person is protected from reinfection. 


Not showing any signs or symptoms of illness. Some people without any symptoms still have and can spread the coronavirus. They are asymptomatic, but contagious.  


A person having a particular disease, disorder, or condition. A variety of criteria may be used to identify cases—for example, a physician diagnosis or a diagnostic test. 


Five or more cases of illness that begin or are diagnosed within a 14-day period and have plausible epidemiologic linkage between the cases (meaning: it’s determined that the cases are in the same place at the same time; the timing fits with likely timing of exposure; and there is no other likely source of exposure). 


Similar in meaning as "contagious." Used to describe diseases that can be spread or transmitted from one person to another. 

Community spread 

The spread of an illness within a particular location, like a neighborhood or town. During community spread, there's no clear source of contact or infection. 


A well person who has been exposed to a COVID-19 positive person or a person’s environment such that they had an opportunity to acquire the infection. 

Confirmed case 

Someone tested and confirmed to have COVID-19. 

Congregate settings 

Public places that can get crowded and where contact with infected people can happen. This includes places like malls, theaters, and grocery stores. 


A family of related viruses. Many of them cause respiratory illnesses. Coronaviruses cause COVID-19, SARS, MERS, and some strains of influenza, or flu. The coronavirus that causes COVID-19 is officially called SARS-CoV-2, which stands for severe acute respiratory syndrome coronavirus 2. 


The name of the illness caused by the coronavirus SARS-CoV-2. COVID-19 stands for "coronavirus disease 2019.” 


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. 


A situation where more cases of disease than expected happen in a given area or to a group of people. 


Your body's ability to resist or fight off an infection. Your immune system is a network of cells throughout your body that help you avoid getting infected and help you get better when you are infected. 


Also called immune-compromised or immunodeficient. This describes someone who has an immune system that can't resist or fight off infections as well as most people. This can be caused by several illnesses. Some treatments for illnesses can also cause someone to be immunocompromised. 

Incubation period 

The time it takes for someone with an infection to start showing symptoms. For COVID-19, the incubation period can be as soon as 2 days, but on average is 4–5 days, but may be as long as 14 days.  

Infectious period 

Period of time during which a person is able to transmit a disease to others. The infectious period usually starts 2 days before someone develops symptoms and lasts TBD. 


Condition in which a person is totally separated from others. Isolation occurs under conditions (for example, having a private bedroom and bathroom) that will prevent or limit the transmission of infection to those around them. Those diagnosed with positive COVID-19 should be isolated for the full infectious period (14 days from known exposure, or 10 days after positive test results). 


A sudden increase of a specific illness in a small area. 


When a new disease spreads to many countries around the world. 

PCR test 

Short for Polymerase Chain Reaction. A PCR test is a diagnostic test that identifies virus in the body. PCR tests for COVID-19 are usually done from swabs taken from the back of the throat or nose. 


PPE stands for Personal Protective Equipment. An approved cloth mask is suitable PPE for students and employees at school. Specialty masks like N-95 and gowns, gloves, etc. are generally reserved for medical professionals. 

Pre-Existing Conditions 

Health conditions in a person of any age that could put them at higher risk for serious illness related to COVID-19 such as: cancer, chronic kidney disease, immunocompromise, obesity, heart or vascular conditions, sickle cell disease, neurological conditions, diabetes, asthma, cystic fibrosis, liver disease, pregnancy, smoking, etc. 

Person under investigation (PUI) 

When a health provider suspects a person has the coronavirus. But, no test has confirmed the infection. 


Similar to “isolation,” quarantine is a term used for people who have not been diagnosed with positive COVID-19. Quarantine is to keep people away from each other to prevent the spread of disease. Stay-at-home orders are a type of quarantine. 

Respiratory droplets 

These are very tiny particles that are exhaled with breathing and speaking. If someone is infected with COVID-19, their respiratory droplets will contain SARS-CoV-2 virus, and these are infectious. Respiratory droplet particles cannot float in the air; they will drop to the ground by gravity. Therefore, after a person exhales them, they fall within 3–4 feet.  

Risk Level 

This can be related to a person’s chances for being exposed to COVID-19 (see “close contact”), or it can mean a person’s risk for serious illness related to COVID-19 (see “pre-existing conditions”). 


Short for Severe Acute Respiratory Syndrome.  


The virus that causes the illness we call COVID-19. 

Signs of illness 

A health effect that can be observed externally, such as temperature, sweating, oxygen saturation, or heart rate. Signs are also abnormal findings on a physical examination that are observed or measured by a clinician (a physician or nurse). Some signs mean that the disease is becoming more severe or progressing. 

Symptoms of Illness 

A health effect that is experienced or felt by the person and is not easily observable by others, such as fatigue or muscle aches. Some symptoms mean that the disease is becoming more severe or progressing. 


This is not the same as a coronavirus test. Self-screenings, like the Magnus daily app questions, helps to identify potential signs and symptoms of illness. Screening in a physician’s office can be used to decide if you actually need a coronavirus test. It’s a series of basic questions about your health condition and recent history to determine risk level.  

Social distancing 

Also called physical distancing. It means putting space between yourself and other people at all times. The goal is to slow down how fast an infection spreads. Stay-at-home orders are a way that the government can enforce social distancing. The CDC recommends keeping at least six feet between you and others around you in public. Social distancing also includes avoiding crowds and groups in public. 


Discrimination against group of people, race, place, or nation. Stigma is associated with a lack of knowledge about how COVID-19 spreads, a need to blame someone, fears about disease and death, and gossip that spreads rumors and myths. 


When a person shows signs of illness. For COVID-19, that includes a wide variety of symptoms: cough, fever, shortness of breath, loss of taste or smell, stomach upset, congestions, headache, etc. 

Viral Shedding 

Viral shedding occurs when a virus replicates inside your body and is released into the environment. At that point, it may be contagious. For the coronavirus that causes COVID-19, it's not known exactly when this occurs after someone is infected. Evidence suggests that the novel coronavirus is most contagious when symptoms are worse and viral shedding is high. However, it appears that someone is contagious prior to developing symptoms, suggesting that viral shedding is occurring even early in the infection.