COVID-19 Glossary

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A global outbreak of disease. Pandemics happen when a new virus emerges to infect people and can spread easily between people.


Stands for Powered Air-Purifying Respirator. They’re the giant full-body suits and helmets healthcare workers wear to treat people quarantined with infectious diseases.


A bacteria, microbe, parasite, fungus, virus or other organism that causes a disease.

personal protective equipment (PPE)

Equipment such as masks and gloves that doctors and nurses wear to protect themselves from diseases.


An infection that causes the tiny air sacs in lungs, called alveoli, to get inflamed and fill with fluid, like mucus or pus. It can be caused by bacteria or viruses. Viral pneumonia can leave the body open for infection from bacterial pneumonia. Right now, bacterial pneumonia is a major complication of COVID-19.

pre-existing conditions

Pre-existing conditions are health conditions someone already has that could make a coronavirus infection worse. Lung disease, asthma and heart disease are pre-existing conditions


A scientific study that is posted online before it has gone through peer-review. Some preprints are good; some are bad. There’s very little quality control. Because peer-review can take a long time, many studies published on coronavirus will be released as preprints. 

presumptive case

A coronavirus case identified by a testing organization. Although other groups can do tests for coronavirus they won’t be considered a confirmed case until the CDC checks the data.


Person Under Investigation. These are people with COVID-19-like symptoms who are not confirmed to have the virus. PUIs can be individuals who had contact with a confirmed case and are displaying some symptoms or they can be people who were hospitalized with severe pneumonia without a different explanation.


Something involving lungs. A pulmonary disease is a lung disease.

pulmonary ventilation

The respiratory system aids in breathing, also called pulmonary ventilation. In pulmonary ventilation, air is inhaled through the nasal and oral cavities (the nose and mouth). It moves through the pharynx, larynx, and trachea into the lungs. Then air is exhaled, flowing back through the same pathway. Changes to the volume and air pressure in the lungs trigger pulmonary ventilation.


Person under monitoring. A individual who does not have COVID-19 symptoms but who has been in contact with someone who is presumed or confirmed to have the virus. A PUM is “monitored” until they’ve gone a period of time without developing symptoms.