Antibody test: Also known as a serological test, an antibody test determines whether a person has had a specific type of virus in the past. Antibody testing for COVID-19 is in its early stage. There are antibody tests for COVID-19 on the market, but the FDA has not evaluated or approved these tests and their accuracy is still unknown. (Source: FDA)


Asymptomatic: A person who has a virus but does not have any symptoms or signs of illness. An asymptomatic person can still be contagious and spread a virus to other people. The CDC estimates that about a third of coronavirus infections are asymptomatic. (Source: CDC)

Related terms: Incubation period, Pre-symptomatic


COVID-19: An infectious disease that causes symptoms including fever, cough, and shortness of breath. Commonly called “coronavirus,” COVID-19 is shorthand for “coronavirus disease 2019.”

Related terms: Coronavirus, SARS-CoV2


Case fatality rate (CFR): The death rate of a disease. To determine the CFR, divide the number of deaths by the total number of cases. The CFR for a disease can change depending on the time period, location, and demographics. The CFR for COVID-19 in the United States is still unknown because of the lack of widespread testing. In China, the CFR ranges from 1% to 5%. (Source: WHO)


Close contact: Anyone who is at high risk of becoming infected after being within 6 feet of an infected person or having contact with an infected person’s bodily fluids. Public health officials may try to identify close contacts through contact tracing.

Related term: Contact tracing


Community spread: The spread of a disease in an area without a clear chain of events or connection to a person who is known to be infected.


Contact tracing: The process of identifying people who may have been exposed to a contagious disease and monitoring and treating those people to control the spread of the disease.


Cordon sanitaire: Preventing disease from spreading by stopping people from leaving an area where the disease is spreading. The term is French for “sanitary cordon” and refers to when military would surround a community suffering from a disease.


Coronavirus: A type of virus that causes illness in humans and animals. “Corona” is the Latin word for “crown” and refers to the spikes on the surface of the virus. Most coronaviruses infect animals, but some can also infect people. SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome) are also caused by coronaviruses.

Related terms: COVID-19, SARS-CoV2


Drive through testing: A testing process where people stay in their vehicles. Medical staff wear protective gear and use a swab to test for the virus. Because of the limited number of tests, many drive through sites still require orders from a physician to receive a test. Find a testing site.


Droplet transmission/spread: One way that disease can spread from person to person. The spray from an infected person’s cough or sneeze contains droplets that can infect other people before the droplets fall to the ground.


Elective surgeries: Surgical procedures that were not essential or not urgent at the onset of COVID-19. Initially, the CDC recommended that health facilities postpone or move elective surgeries to slow the spread of COVID-19. The CDC now advises healthcare systems to balance the need to provide necessary services while minimizing the risk to patients. (Source: CDC)


Epidemic: An outbreak of an infectious disease that affects people in a specific area or community.

Related term: Pandemic


Essential activities: Activities that were permitted to continue during stay-at-home orders. Essential activities included accessing necessary things like food, health care or prescriptions. Maintaining physical distancing is important when going out for any essential activities.

Related term: Stay at home


Face mask: A protective covering worn over the nose and mouth to prevent the spread of disease. The CDC recommends wearing a cloth face mask when going out in public to protect yourself and others. A cloth face mask can be made with common materials including a T-shirt or bandana. (Source: CDC)

Related term: N95 Respirator


Flattening the curve: Reducing the number of COVID-19 cases at one time to ease the pressure on healthcare providers and public resources. Physical distancing and other protective measures can slow the spread of the virus and flatten the curve. (Source: NPR)


Herd immunity: When most of a population is immune to an infectious disease, people who are not immune are indirectly protected because it is harder for the disease to spread. For example, measles, mumps and polio are now very rare in the U.S. because most Americans have immunity through vaccines.


Immunocompromised: Having a weaker immune system. Someone who is immunocompromised is at greater risk for contracting a disease due to a preexisting medical condition such as asthma, heart disease and diabetes.


Incubation period: The time between catching the virus and beginning to have symptoms. The incubation period for COVID-19 can range from 1-14 days but is usually around five days. During this time, an infected person can still be contagious and spread a virus to other people.

Related term: Pre-symptomatic


Isolation: Preventing the spread of disease by separating someone who is sick from healthy people. Isolation includes staying at home and not sharing a bedroom or bathroom with healthy family members. Healthcare providers can help patients determine how long they need to isolate.

Related terms: Quarantine, Self-quarantine


N95 respirator: A type of disposable face mask that healthcare workers wear to protect themselves from infection. The mask fits tightly around the nose and mouth and can filter more virus particles than cloth masks or surgical masks. (Source: CDC)

Related terms: Face mask, Personal protective equipment


Pandemic: Worldwide spread of a new disease that most people are not immune to. The World Health Organization declared the coronavirus outbreak a pandemic in March. (Source: WHO)

Related term: Epidemic


Personal protective equipment (PPE): Gear worn by health professionals and other essential employees to prevent the spread of disease. PPE includes surgical masks, N95 masks, gowns, gloves, and eye protection.


Physical distancing: Keeping at least 6 feet apart from other people to prevent the spread of disease. Working from home, cancelling in-person events, and visiting with loved ones online are all ways to practice physical distancing.

Related term: Social distancing


Pre-symptomatic: A person who has recently been exposed to a virus but has not developed symptoms or signs of illness yet. Someone who is pre-symptomatic can still be contagious and spread a virus to other people. Testing can confirm cases of COVID-19 while a person is pre-symptomatic. (Source: WHO)

Related terms: Asymptomatic, Incubation period


Quarantine: Separating people who may have been exposed to a contagious disease to see if they become sick. For example, travelers may be quarantined at a port of entry to prevent the spread of disease.

Related term: Self-quarantine


SARS-CoV2: The specific type of virus that causes the disease COVID-19. The full scientific name of the virus is severe acute respiratory syndrome coronavirus 2 and is commonly called “coronavirus.”


Self-quarantine: Choosing or volunteering to be quarantined after being exposed to a contagious disease. Self-quarantine usually happens at home to avoid spreading a disease to other people. Health experts recommend that individuals who may have been exposed to COVID-19 self-quarantine for 14 days after exposure, take their temperature daily and avoid interacting with people who are at high risk of complications from COVID-19.

Related term: Quarantine, Isolation


Serology: The study of blood serum. Serological tests, also known as antibody tests, are used to look for the presence of antibodies and to determine if a person has had an immune response to a virus such as COVID-19. Serological test results are important in detecting infections with few or no symptoms. (Source: CDC)

Related term: Antibody test


Stay at home: An order by a city, state or county government requiring residents to stay home and only go out for essential activities or to work in an essential business. Some areas may also allow exercising outdoors. Stay-at-home orders help prevent diseases from spreading quickly from person to person.

Related terms: Essential activities


Surge: A quick and sharp increase in the number of COVID-19 cases over the previous days or weeks.


Ventilator: A machine that helps patients breathe by moving air in and out of their lungs. Some patients who are hospitalized for COVID-19 will need a ventilator to help them breathe.