COVID-19 Glossary

Coronavirus and COVID-19

The terms coronavirus and COVID-19 are often used interchangeably, but the two have different definitions. Coronaviruses are a “large family of viruses” that cause a range of illnesses. Different strains of coronaviruses lead to different illnesses, and the new strain of coronavirus – also referred to as the “novel coronavirus” – has led to the disease COVID-19.

Incubation period 

The incubation period is the time it takes for an infected person to start showing symptoms. The average incubation period for COVID-19 is five days. 

Presumptive positive case

A “presumptive positive” case is one that has been confirmed by state health agencies but has not been confirmed by the CDC.

Confirmed case

A coronavirus case that has been confirmed by the CDC through laboratory testing.


An outbreak is “a sudden rise in the incidence of a disease,” which is usually confined to one area or group of people. 

When there are enough outbreaks (the number is determined by the monitoring agency), in places beyond that initial spot, that amounts to an epidemic. 

A pandemic is an epidemic that has spread to multiple large regions, like multiple countries or continents (the number is determined by the monitoring agency). 

Quarantine/ Self-Quarantine/ Isolation

Isolation is separating those with a contagious disease from those who aren't sick. 

Quarantine is the separation of people who may have been exposed to a contagious disease from other people as a medical recommendation.

Self-quarantine is when someone voluntarily removes themselves from contact with other people. 

Community spread 

This is when the virus has spread throughout the community where routine contact within that environment is assumed to expose one to the disease.

Social distancing

Social distancing refers to various methods used to keep people from being in close quarters so the spread of the disease can be reduced. Social distancing measures can include limiting large gatherings,  providing farther speaking distance, and staying at least an arm’s length apart from others.


Containment is the strategy of trying to contain the spread of a disease, to simply eliminate the possibility of further spread. 


Mitigation is the strategy used once there is community spread of a disease. Mitigation includes social distancing and other public health directives like washing your hands, avoiding touching your face, and staying home when you’re sick, all of which may decrease transmission through preventative measures.

Essential Travel

Essential travel is travel that is absolutely necessary and required. For example, travel in order to preserve the safety of a research subject and cannot be postponed.